As someone who's done lots of wood and joint testing over the years I can say this is an excellent video. Small boards like 2x4s see structural use mostly in two cases, vertical studs/columns, and truss members. The testing in this video was based on Fb bending. This is primarily the roof truss case, where a board member is horizontal-ish in orientation and loads are applied along its length. Such loads can be from from the roofing materials, people, snow, wind, etc. And yes, the values allowed to be used by engineers for wooden structures are very conservative and have plenty of reserve strength. Consequently, failure of wood structures usually occurs where wood is joined rather than in the wood itself. Bolts, nails, plates, glue, etc. are all used to join wood and the building codes have plenty to say about this as well.
@eyesonly4451 Thank you sir/ma'am, your comment is very much appreciated. It's also good to hear from someone who has attempted similar tests before. It's more to know that I didn't miss something instrumental. Many people comment about the use of 2x4s and that the test is pointless, but I think this conservatism extends to all sizes. I only tested 2x4s because my press can't break larger stuff😅. Cheers!
I learned a lot from an addition I recently made on my house. In California we use a lot of straps and brackets to home building. I'm assuming that really adds to the joining strength. Also, it had to be wrapped completely with 1/2 plywood and specials nails for additional shear strength. Seems like crazy over kill... But I feel safe in that room.
@@DoubleDoubleWithOnionsEarthquakes drive much of the building requirements out there. All the metal straps, special nails, and plywood are designed to resist motion induced shear loads that can occur during an earthquake. Such back & forth motion can rip a wooden structure apart at its joists if improperly built. Properly built wood and/or steel structures are the safest in earthquake zones. The worst is masonry construction, which can crumble like a dry cookie during an earthquake.
As a retired framer of 45 years who changed his college major from engineering after almost two full years (to psych and econ), I should mention 2x4s are specifically disallowed by code in floor and roof framing (at least in California). For decades 2x4s were used as rafters and chords in trusses, but now just the verticals as mentioned by eyesonly4451. Another observation, that has little to do with the matter at hand, is the two photos @ 1:53. That may not be wood failure looking at the floor components. The way the floor fell, the separation of failed components from the others (the wood would split, not shear), and looking at the observable wood cuts leads me to believe it was something else like human failure (design, installation), though the second photo of the pair looks like there was some trimming of the floor joists in order to begin the repairs. I would love to know the stories behind those two photos. Interesting video, thanks.
@@TheEngineeringHub If the point of the video is to point out conservativism in building codes, then ok, but you did miss the mark generally. 2x4's are rarely used in the scenario you were testing for. They are generally used in wall studs and therefore the use-case is in compression along its length where it can hold thousands of pounds. Out of that use case (framing walls), half the time they are not even load-bearing and are just used to hold drywall or doors in place. A more useful test would be to test their compression strength by wood species and grades and some cases where they are bowed, twisted, and/or full of knots. I realize your setup cannot likely accommodate that though. The quality of wood products nowadays is junk compared to the past. Most big box stores sell you fast-growth yellow pine compared to the Douglas Fir I constructed my house from 30 years ago. In addition to them being very knotty, it is difficult to find straight ones with any consistency, and they are very light-weight in comparison to the past. Nevermind the dimension change from true 2x4 to 1.5x3.5 from many years ago. My first single-family home was a Sears home in Cape Cod style built in the early 1960's. It used true 2x4's as roof rafters. It will, no doubt be there still in another 70 years. The quality of the wood was very dense, hard, and heavy. Another useful test scenario would be to test true 2x4's to current dimensional lumber. You could see a significant increase in strength (in your bending test) compared to US dimensions and what a "mere" 0.25" makes in both dimensions. To make it useful to point out the affect of dimension on strength, you would probably have to mill several of each kind from the same log to make it fair as you cannot buy true 2x4's from a big-box store anymore as they would need to be custom-made.
Typically (to european code) you should not use 2x4 for structural load. Anything rated C14 or lower is consider non structural and should just be used where structural failuers are not faital.
The illustration of all 100 potential 2"×4"s under the bell curve was really good. I wish more statisticians explained using that method, because I think a lot more people would understand the visual distribution instead of fighting engineers about the numerical one.
I'm a mathematical non-visual person (and a statistician). The numbers are all I personally need. But even some other engineers prefer to see diagrams. My struggle is that the same info that I can describe verbally or in writing in 15 seconds takes two hours to put together in a diagram. There's no real "answer" here except trying to find how to either describe it more effectively or to figure out how to put diagrams together more quickly. I've worked for many years on both, there's no perfect answer.
Note that if you've bought 2x4s in the big box stores (HD I'm looking at you) they aren't even 1-1/2 x 3-1/3 but almost 1/8" smaller in both dimensions. So I built part of a project with one delivery then had huge problems because all the lumber was smaller. I went to the store intending to return the lumber I thought had been missing BUT found out everything they were getting had experienced 'shrinkflation' (like in the grocery store where the box is the same size but has less contents but the price didn't change, so you ARE paying more for less). I went to a couple other suppliers, found some older bundkes still the old size and bought all I could afford to stock & store for future projects. But the point is that smaller 2x4 aren't going to meet the strengths the old ones did. But that wasn't the problem I had, we built some walls with a mix of old and new lumber and the dimensional differences weren't noticed until the sheetrock was being installed, going fromba std board across to a narrower board then back to a standard board leaves a gap under the sheetrock at the narrow board and caused the screws to pull through there. Yes, crappy builders don't care and a double bay of unsupported sheetrock would probably last long enough for the warranty period to expire but that's not how I do things. Andvif you built a whole house out if the smaller lumber, tolerance stacking would throw off your prints dimensions eventually. So new prints would have to be drawn up? The mills aren't doing this on their own, the big wholesale outfits buyers have to approve (and maybe even instigated it to get more sticks of lumber out if trees so more profits?)
Also the fact that the new growth is harvested at a much smaller diameter could play into the push for another size reduction (just speculating, I don't really know) but the motive of higher profit margins is probably baked in. For now the high reserve strength seems to cover any potential cut on the dimensions.
@@TheEngineeringHub yes on the strength but it really does create problems when your using material that's smaller than specified. If a wall is thinner because the boards are smaller, will prefabricated window boxes fit? Code requires that utility lines holes through studs have a certain amount of wood left on each side, I forsee some inspectors who are picky failing some installations (sink drain lines running horizontally through a std wall pretty much have to be centered to leave enough wood on each side for compression strength support, i didn't measure but if the line was just offset slightly with the smaller stud then it wouldn't have the code required measurement.
I have an older house like 100 years old and the two by fours are real full dimension 2x4 inches. I was shocked at what passes for a '2x4' today. Not even close in deminsion
I have never had an engineer call out a 2x4 for a floor joist. They are insufficient for both strength and insulation. But probably a great reference for testing since they are the smallest structal member used in a residential home.
You would need an engineer to design a floor system with 2x4's. They used to be included in span tables, way back when when I was using UBC. I'm not sure if the IRC ever included 2x4's. But, they are sufficient, and you can even have smaller lumber engineered within a floor joist system. There are a lot of variables. Common species like SYP are weaker than Douglas Fir. The number of members per joist, span, spacing, deflection, lumber grade, loads like live loads, seismic loads, shear loads...all play a part in the design criteria. The tests done in this video were likely performed on stud grade lumber. That is, lumber that is to be used in vertical position. It doesn't carry a number grade, and I don't really know the comparison between studs and say a grade 2, but I do know a stud would not be as strong as a grade 2 piece of lumber. The standard in most codes is number 2 or better. Although, the IRC allows the use of #3 graded lumber without the interjection of a structural engineer.
Shed floors in 10'x8' and under are often 2x4s which were done by an engineer. Course they aren't a living space load and having a springy floor isn't a big issue in a small shed.
@@Cragified you can also pick up strength with blocking or using 5/8" - 3/4" plywood on the floor, instead of OSB. There's not a whole lot of code to shed building in most areas.
@@Cragified Exactly. And most people building a backyard shed are going to throw a few cinder blocks under the floor beams to massively decrease the amount of spring in the floor.
C14 is not allowed for load bearing structures here in Norway (I guess that applies to other European countries too). C24 is what is used for house building.
@@arntoveh75 Lucky you! I don't so much care about how large these 2x4s are as I wish they were more uniform. CLS timber here in the UK which is the american style 2x4 (38x89) is more consistent than the UK style 2x4 which is supposed to be 47x95, but can be 44x93 or god knows what else. I wish they would make them all 44x95 and make them consistent like CLS.
The code assumes proper framing procedures which rarely occur. Most of the framing I've seen in the last 10 years makes me afraid to walk into the house.
Everyone keeps saying "they don't frame/build them like they used to!" Bro, the post ww2 baby boom housing was way worse. Older houses just didn't have a youtuber content creator walking through with a magnifying glass trying to generate clicks.
No woodworkers that knows his stuff and cares, would have used that beam you break at the beginning with that node in the middle. Got to read the wood and recognise the weaknesses.
@@JeremyBell idk man, plenty of older homes have their problems but I see plenty of brand new construction where thousands of pounds are held up by an inch of air and about 10 nails because people cant seem to get their cuts right. it's just geometry
The same thing is valid for 2x8. And also we never use C14 graded wood for bearing constructions. Watching US and CA videos about timber frame building was quite shocking for me tbh. My first thoughts we like "is it really legit?". In Europe we use C24-C30 graded wood for frame walls studs. The material has a smooth surface and rounded edges, so an insulation slides inside with no resistance and has a smaller contact area with plaster board. Vapor and wind membranes are taped, so the construction is tight. In US videos I see a raw surface of studs with unequal profile, the insulation is just pushed in like no one cares and nice finish outside. Why so?
I did, cheaped out on a wood pile cover, very small slope, 2x4's on 2' centres across maybe 8' span with steel roof. Live in a heavy snow load area. At least one of the 2x4s snapped under the spread out load, must have been over at tonne up there, so I eventually reinforced a few with 2 x 6s. Since it's not life or death I didn't care about collapse, but was actually surprised it held up almost a decade with so little damage. Wood is strong!
here in England you were only able to use stress graded timber in the construction of a dwelling , it was stamped by an inspector and clear for all to see , they got rid of that rule some years ago
In Sweden, the smaller dimensions are wood that has been planed. If the plank is sawn, it has larger dimensions. We use the metric system, but I use inches when it comes to lumber. I say, "Two inches Four" and if the plank is planed I say, "Two inches Four planed"
Yeah, 2x4s were the full 2" x 4" pre-war and not planed, so they were rough sawn, here in the States. Then there was a period of a few years when they were 1-3/4" x 3-3/4", finally becoming 1-1/2" x 3-1/2" and fully surfaced and planed. If my memory serves, they may have begun the transition right before we entered the war, like '39, '40, or '41. We can still order rough-sawn dimensional lumber for design elements, and the older guys (I'm raising my hand here) will still order our larger pieces (6x, 8x, etc.) by appending S4S, for surfaced four sides. I never found a definitive reason why the transition was made, but I am assuming much had to do with cost savings (8X volume versus 5.25X volume, a full one-third savings) when people realized that vertical members did not need that much mass with the load they were usually carrying, along with the more pleasant smooth surface. I could go on and on, but I'm sure I've bored to death more than just a few.
Interestingly, we right across the sea from you, in the Baltics, calculate with the same Eurocodes, but wood here is in mm, e.g. as 100x50mm (not even 95x45 as in this video)
cable sized holes drilled in the centre of the beam, should not decimate the beams strenght (the beam top is subject to compression, the bottom to tension, in the centre those forces should be in equilibrium)
@@laus9953 but you are reducing the amount of wood on either side. Usually the holes themselves are larger than the cable or pipe running through them as well.
My house was built in the 1950's (US) and all the lumber is dimensionally 1/4 inch taller than what you would find on the shelf today. The growth ring patterns are very tight ("old growth"). If you're ever demo'ing old growth structure and are able to salvage any of the wood for reuse, it's worth it. None of what they sell today will match its strength (even holds screws and nails better).
I appreciate your effort and methodology on the testing. Very well done. For the record, any contractor who uses 2x4's for flooring joists should be in prison. 2x4's are good under compressive loads such as vertical wall framing, spaced close enough together to well exceed the loads encountered. NOT flooring joists.
Fair point! Just to clarify, I think this comparison extends to all lumber sizes. I tested 2x4's because my hydraulic press would have hard time breaking 2x6's or larger😅
It would be perfectly suitable if the span is narrower (in the video it's 2.4m) and if you double up on the spacing, so nothing against a 2x4, it just depends on the usage.
My house is 150 years old. The wood in it is just nuts. It would never pass code today, but it’s still standing. It probably has 2x more wood in it than a house built today.
In addition, the wood used probably is not from a fast growing industrial type of forestry (spruce) but a naturally grown broad leaf wood which is substantially stronger than fir or similar used today.
@@robertrjm8115 the floors are 3/4” by 4” oak on top of 1”x6” pine sub floor. The supports are whole log pine. Everything else I can see has been pine so far. But it is different. It has age hardened, but the grain seems more dense as well. All of the spans are different as well. Seems to be around 24” on center. Every project is like an archeological dig. I find all sorts of strange shit buried in the yard. Found an entire chimney once.
I've found that really old 2x4's can shatter. It's like the sap has dried out and there is not much holding the layers together. I can take a hammer and knock a stud out of the way, and it will splinter into pieces.
The fact that it's still stand and probably solid af is a testament to thos who built it. Craftsmanship, integrity, and quality are a thing of the past. These days you pay $1M for a house built with OSB, cracked roof trusses, and wet studs....but it all gets covered up with high end finishes so it LOOKS fantastic. It's like polishing a turd ffs.
@@OU81TWOnot all of them, I replaced a furnace on a 10 year old house once were the main floor of the house was doubled up 2x12s that were run 12" center to center. I went into the basement and looked up at all those joists and I was floored. You could drive a semi across that floor.
As a builder w/ 45 years I'm glad that code factors for the lowest common denominator. I've been subscribed for quite some time, and appreciate your unbiased opinion. 👍
I work at a place specializing in reusing old wood. The 2x4s are actually 2x4. The grain I see are from much larger trees. I am also amazed at how straight the old wood is. Even hand hewn is amazingly straight compared to modern lumber. Great video
I was involved in a project rebuilding a four story mansion built in 1903. It was completely dismantled and trucked 1500 miles across a little of Canada. I spent a month in a field sorting out a couple of tons of Italian terracotta brick that trimmed the exterior. Over there was the 2x4 framing. They used single pieces on the exterior, 30 40 feet long, straight as arrows, full 2x4 fir. They didn't use it because you couldn't drive a nail into it.
Yes. If you will pardon the pun, your statement at the end that the quality of the carpenter ,,, You nailed it. You also tested four 2X4s, at least one of which was strictly a No. 3 grade. Size of knot, type of defect, position of the knot or defect.. A good carpenter accounts for all of these. If there are two elements that are bowed,, I will combine those elements in oipposing directions. If the knot or defect is so large the grade should have been a No.3 or No.4 that IS the element I will use for cut up blocking. Or,, I HAVE been known to over order on the basic stock just so I can reject pieces that are substandard. The load or bunk is unbanded in the front yard, and if an objectionable piece is encountered, It is simply placed in a returns stack. I will not use garbage.
# 2 should never be stamped at the; Mill for a #3 or worse. Standards set, when deligently applied and followed always worked. Should not be your job too grade what already was suppose too be done. If that was required, then they could let go the grader and reduce the purchase cost. ACCOUNTABILITY!!
@@edwinlipton Edwin, your faith in the grader or system is misplaced. Yes, I have seen nearly flawless grading and the bunk ( a bunk is a banded 'lift' of 2X4s approximately 360) received was of superlative quality. However it has also been that I have received a bunk that would barely make dunage or pallets. 2X4s unusable in any wall and 2X10s or 2X12s with large knots in the edges, trash. The real world and jobsite contracting can be exceedingly ugly. And, If I halt the project because of poor delivered materials, it is I who pay the penalty. In lost time, wages, and even the job when the principal contractor just hires someone with less integrity, and I lose the job all together. (In which case, I don't want to work for him at all.)
@Sailor376also I know the exsperience. I too was a Mechanical Lic Contract Plumber for 17 years of a 27 year career. Cut short for no other reason than Physical health "bones". So I understand what your up against. Once was a time when "we" only had too do our desired trades with learned skills and focused attention for a decent profit of reward. Now however,, youve got too do everyone elses job to get your contracted job alone completed. Including regrading lumber quality and that General contractors slice of pie as well. For me; it was poor quality in mass produced "nibco" copper pipe no longer produced in the U.S. but south in Mexico. They'd bunndle it up for mass shipping with steelbanding, so tight and stacked so high that it egged and mared it too where a round nibco fitting could no longer join the pipe to fitting without alteration by a pair of channel lock pliers slowing down the water pipeing process. Nothing one could do about it but bitch and accept. It was due too profitization and production cost cutting. ie, cheap Mexico labor and utilization of Mass over sized loads of copper being transported. I worked through out the western states, same everywhere. Big, small, tracts, industrial, institutional, commercial retail, or stick built customs. Everything but sky scrappers. Wanted those. But never got too. Loved the trades. Building was more than a paycheck too me. Broke today because of the shysters taking the profits who knew absolutly noting about building, but knew how too profit. Boy do they!
@Sailor376also ya mis understood me. I have NO Faith in mass production at all. It is profit driven and the reason for Boeing's demise. Planes dropping out of the skies, Star liner debacel and my once belief in the Big 3 autos now producing over priced junk.
@@edwinlipton Big 3 ,, over priced,, Yep! It was as recent as three years ago I came upon a dealer with a loss leader for an F-150, 19,999,, Of course he did not have one in stock and the upsell began. And I nearly, and should have cornered him to order and produce the 19,999. I just need a truck,, no bells and whistles, high school girl toe nail sparkle pink and blue tooth everything,,, all absolute junk if you are going to throw lumber, bricks, and blocks in the bed. Current price is doubled,, in three years 39,999 and there is not a stripped down pickup anywhere, 60k to 120k for infotained 6 cup holders 12 speed auto, 3 cylinders and blue tooth start the truck remotely from the next city over. JUNK. My most recent disappointment, insurance. I took a good 2009 with exactly the engine I wanted, and rebuilt it. Paid 4.5k now into it for 14.5k The insurance will not cover it. Their position is that it is just and only a 2009 and worth 2500. and they want to charge me 1000 per year to cover that 2500 Time to go self insured. BTW Fun to discuss with a fellow contractor. Thanks !
Having been in the trade for over 40 years and from design, specification and engineering there are a myriad of specific specie, grades, and grain orientations that will dictate the performances capable for framing members and their respective loadings and uses…we have used 2 x 4 stock for mezzanine floor joists to reduce heights in low headroom instances, spaced rather closely 12” oc and 8” oc yes this is atypical but it’s still there some 35 years later and was used for static loads.
Despite some of the comments here - I'm actually extremely grateful for this video. A lot of folks or talking about "there's a knot there, therefore this is not legit" BUT the reality is most 2"×4"s at the big box stores or numbers will have lots of knots. I "overbuilt" an outdoor sectional for the family sacrificing aesthetics for something I know people can jump on, put all their weight on or whatever without ever having to worry that one of the 2"×4"s would break. After seeing this video it reassures me that it doesn't hurt to play it safe.
What ever the dimensions and species, the grade, etc, the engineering is done from simple tables and they tend to be quite good. I've never had any kind of framing failure in 55 years. And I'm still working, too! The 1.5" x 3.5" has not changed for many decades, I think since 1964, when I believe it had been reduced from 1-5/8 x 3-5/8," and it had been that for decades. And people are STILL saying, "You mean its NOT a REAL 2 x 4" ?! No ma'am, its a sort of funny deal we get from the lumber companies. But I assure you they are entirely adequate." Now of course we use 2 x 6, if you can handle the nomenclature, and we went to 2 x 6 to accommodate more insulation, also an old story. The whole thing reminds on of other questionable dimensions, but lets not make this more complex than it is.
In Norway a 2x4 is 48x98mm from the store. Dimensions are round numbers minus 2mm for lumber. Glued laminated timber have other numbers in height that are typically rounder. In Ukraine a 2x4 is 50x100, but is green and not kd.
Stud material is meant for vertical applications in a wall diaphragm, not to be used as horizontal framing members. Therefore the load is applied through the longest axis, not either of the shorter two. Also they gain ability to carry VERTICAL load by the addition of sheeting systems, both interior and/or exterior. Usually stud material is an inferior grade of lumber from inferior tree species such as spice, pine or fir. The only times I ran into specs for using structural lumber in stud applications were when the walls were above normal height. For example, building an addition onto a shop with 16 foot side walls the engineer specified 2x6 MSR studs. That’s Machine Stress Rated. Structural dimensional lumber is higher quality and meant to be used in horizontal load applications such as headers, beams or floor joists. It’s not only made from better species of wood, such as Douglas fir or larch, but also graded higher by visual inspection. The code books have tables to reference that give a designer guidance on acceptable spans for different dimensional lumber sizes, types and spacings. Suggestion: do a stress comparison between a 2x6x8 stud grade and a 2x6x8 Douglas structural lumber. I think that would be more educational to the average person who goes to the home improvement box store and doesn’t know what piece of lumber they need for their project. Stud grade lumber shouldn’t be used in horizontal framing that experiences a vertical load.
The correct answer is "none" because 2x4 are not sourced from wood that is used for making beams, they're for compression longitudinal loading. You can simply walk down to the local wood pile and discover this with a small screwdriver: they weigh about 18% less per board-foot than actual beams do!
Go up into your attic, or into a multi-story apt complex's cieling. You will 9 out of 10 find engineered truss framing, or floor joist girder engineered 2×4 support joists supporting the next level with 3/4" sound deading lite wieght concrete poured for the units. It's materials and engineered application that make the difference. Use rubber if you will,, with the right engineered application,, it will stand.
1:53 Those are not broken joists. In this case, the mode of failure is pretty easy to see. They did some kind of poorly made scarf joint on that floor.
Graded C14 apparently - I have never seen anything less than C16 in the UK and C24 is pretty common. Looking at those C14s, I wouldn't make a chicken run with them.
I bought the wood in Denmark and I would say most of the lumber (at that store at least) was graded C14 as you can also see in the video. I'm not sure if the graders are just being overly conservative because the yield stress was way more than 14 MPa although the boards did look very poor on the outside.
@@TheEngineeringHub Many thanks for the reply. It's a long time since I did the sum but if you take the text-book figures for the tensile strength of pine you get far higher ultimate load capability than the ratings. Also, the degree of pessimism applied to, for example, roof structures seems to have increased considerably over time. Some years ago we had a garage roof replaced. The original, some 70 years old was a corrugated iron job supported by 2 x 4s at a considerable spacing. Its demise came only after a considerable period with the sheeting rusted through in places. Its replacement, to modern regulations, included a 10 x 4 cross-beam to halve the span and 6 x 2s at about half the spacing of the original 4 x 2s. I did wonder if they had stressed it to allow the car to be parked on rather than under the roof.🙂
@@ColinMill1 I was told that old timber was stronger per cross-section than modern one because it tended to be more slow-grown and hence denser. I am in the middle of refurbishing a 90 year old house, and I can tell you that the 90 year old 2x4s that I am removing are noticeably heavier than the new ones I am putting in.
@@chrisgemmix0815 It's possible. I have just measured the density of some new offcuts here and 480 kg/cu.m which is in the middle to upper end for white pine but there are plenty of pine species it could have been in the past that are denser. One thing that is different here is that, going back 60 years 2 x 4 sawn really was 2 inches x 4 inches. These days it's a good 6mm under that in both directions. Even allowing for that the regs do seem to have gone extremely pessimistic over time.
yes, more videos about complex sub aspects please ! and like another commenter wrote - would be fantastic to see very old recovered beams tested for strenght comparison !
My father in law was an aeronautical engineer. He'd visit and work on our house and when making plans he's spend a day covering pages of paper with structural calculations. Finally, he'd say "but never know how strong this particular 2x4 is, so let's just use a 2x8". Everything ended up strong, but heavy, but at least it didn't have to fly.
Excellent video, Steve - all the tricks you've developed over the years -- like holding back some of the part C -- are invaluable for us DIYers so we don't have to learn the hard way! 👍
Dimensional lumber varies so much. My old house has 2x6 floor joists spanning 16ft at 24” on center. They are old growth pine and are so much more dense than new growth. The rings on a crosscut of wood are super close. I’d love to test their strength
I would heavily suggest reinforcement of the floor. That is well, well over the load demand of that lumber. My old house has 3x12(not planed) as for joists 12" apart over 16' span and I think that's just over what's required.
My house was built in 71', 2x6 @16" oc, 16' spans. I went under the floor and poured concrete footers mid span and ran double 2x12 beams perpendicular to the 2x6 to support them. I've been a framer for 25 years.
It's as much about the freedom from knots, the closeness of the grain, and the species of wood as anything else. With 45 years in building the framing wood I was taught to cull out for returning is now considered to be adequate for milling trim. There might be 10 good studs per bundle now, with the rest being substandard. That's why the N American acceptable loading is so low; our wood is crap.
Love these videos. Now for the questions. Can you purchase a 2 x 4 with no knots? I would guess using a wood with a higher Janka rating would be better. Both probably costly
The piece of wood you have between your press and the beam is spreading the pressure out, which the standards authority tests might not do? (IDK, just noticed this, that's all).
I suspect the same, it probably helps distribute the load and achieve a slightly higher capacity. But I don't think that it would help more than a few percent, max 10%.
It is a very good thing the actual strength tends to be much higher than the code values. Seeing boards made into Swiss cheese with penetrations and knowing the torsional and sheer forces from high winds and the incredible static loads from snow and ice those conservative numbers are the right ones to use.
In my region in Canada, some lands are planted with Norway spruce because spruce is well-suited to this area, and Norway spruce grows faster than native species. The purpose of this was originally to supply the paper mill in my city. However, the paper mill has been closed and demolished for over a decade, maybe even two. Landowners with these trees now struggle to sell their logs at a good price because this spruce isn’t high enough quality for dimensional lumber and stud (at least or canadian and american stdards). Maybe that’s why a 2x4 is a bit larger in Europe? I don’t know if that has changed; I had some wood cut on my land a few years ago. Luckily, I didn’t have any Norway spruce.
I am an European structural engineer and using EC5 in my work. There is such a country in Europe like Norway, whey have their own building code. Every time I design a timber structure for Norwegians, they claim that all ridge beams are so much over dimensioned. They use lower coefficients in their calculations and beams and joists have significantly smaller cros-sections. SO there is such a joke in our region, that as soon the wood crosses the Norwegian border, it feels Viking power and becomes stronger.
Anyone that does remodeling of houses from 75-125 years ago can attest to the fact that lumber is way stronger then people think. Ive seen some seriously undersized framing by todays standards and those places havent moved, sagged or shifted an inch in 100years.
Does the code describe when the 2x4 colapses or it's maximum safe load? I mean, I'm not a structural engineer, but as far as I know, they have something called 'safety factor' or something like this, which changes depends on the application. In some application it can be 2 in some other it can be 5 or more. eg, if that board failed at 500kg load, then can be used for predicted load of 250kg in flooring (factor 2), but only for predicted load of 100kg for a bridge (safety factor 5). btw. those factor values are just random numbers, to describe my idea.
This is why 2x4s are never used for floor joists. I'm unaware of any jurisdiction in the USA that allows anything smaller than a 2x8. Wuold love to see this test repeat with and without pressure blocking, and bridging mid-span
It also depends on the diameter of log that the 2X4 was cut from, grain orientation and different stress loads that are applied in various applications.
Really cool comparison of code capacities and actutal test results. Keep the great content coming! Do you know why the eurocode chose not to include a short term loading factor?
It would be interesting to see the strength of them turned the other way. I know guys make temporary platforms with them, I always questioned how safe it actually was.
Could you make a video explaining shear strength for residential houses? In particularly if using OSB vs Termo-Ply or similar Structural Sheathing with 2x4 framing? My house is built using this in North Texas and I have always wondered what the strength breakdown would be actually vs what is in the Dr. J evaluation report.
For whatever it’s worth, home building in the US can vary widely from region to region. I grew up in a very rural county and they STILL don’t have any building codes there; the only thing you have to get permits and inspections for are wells and cisterns. That said, as I understand it, most average sized homes built these days in the US use engineered floor joists and engineered roof trusses as well. 2x4 are more used in vertical applications in the general framing process. I’m definitely not an expert, but those have been my general observations.
@@justayoutuber1906 The whole county literally has zero zoning or land use regulations. Also in Colorado, no state wide code other than for schools, state owned buildings, and multi-family. It's an extremely rural county with only 3300 people in a pretty large area. Poverty level of 19 pct. population of 1.4 people per sq mile.
Not surprised the tests are so different. We're dealing with natural resources that are hard to standardize. Wood can be very inconsistent. These tests are useful, but it's rare you use a single 2x4 in isolation. Also, 2x4s are never used for floor joists, only for wall framing.
In Florida we have been getting a bunch of lumber from Europe the last few years. I guess beetles were decimating the forests there, so the decided better to just go ahead and clear the forests and sell cheap. This lumber looks like you would imagine a dying forest could look like. It looks like the trees were sick.
Technically you did not test a 2z4. You tested a beam less than 1.5 x 3.5 inches if a US standard because of the knot. The knot on the edge reduces the actual strength dimensions of the board at least by the dimensions of the knot. And the length of the beam is important because longer = weaker. Just some thoughts.
I have tested thousands of pieces of solid lumber and fingerjoined lumber in various ways. Tension, bending break tests. It is pretty crazy to think a high grade 2x3 fingerjoined lumber can easily handle over 20000 pounds of force in a tension test before it breaks.
The thing that always scared me at looking calculations with wood when I was in school was at school was species and knots. After doing woodworking as a hobby for a few years, those are kinda non-issues (for construction lumber you don't really get a choice with species, and just avoid knots). Grain orientation should also matter for how the load is applied, everything in the video looked like flatsawn pieces but if you go though a pile, theres a handful of quarter sawn looking pieces as well. I also question the values in the code, if they are using numbers measured in the early to mid 1900's, it is likely that the wood they measured is not what we are using today. Today's lumber is farmed and optimized for growth, that means farms want the tree to grow as fast as possible so they can harvest it and grow the next crop. Since tree rings are made at a constant rate the spacing between rings is much larger in farmed trees compared to trees growing naturally in a forrest. Old growth trees starved in their early years, they grew in the shadow of mature trees and would have took much longer to get to the same size thus their wood would have many more ring per unit length. The rings are what provide the strength and durability, and if what was measured was old growth wood that has 5x the density, it would be almost an entirely different material.
@bryanthiga3198 I love this comment. I actually looked into that very issue and made a video about it about a year ago. You may like it as well. If you end up watching it, let me know what you think. Cheers
It appears the weakness of 2*4s can be easily remedied by reinforcing the center with a long metal plate on both sides or use glue, fasteners and wood.
Excellent information. I rebuild my own deck with 2x6 framing. I over engineered the crap out of it for good measure. With this information I feel even better that I can drive a tank on it without issues😂
@tuzzogetti Yeah, I started to suspect the same since all failures happened on the tension side. But I had already started with this setup, so I continued this way. It could be helping for sure, but it wouldn't be a huge contribution I don't think.
Where I’m from in Canada, my load bearing framed walls are never 100% touching/bearing. IMO this is why code exists to factor in mistakes in framing and variance in quality of wood being used.
Good video. It's a small amount of accurate information. People who argue should simply add it to the other information they already have do their own thinking and stop asking for someone else to answer every question.
@MichielvanderMeulen I calibrated and tested the cell extensively before the experiment. I am comfortable saying that it matched with the loads displayed on the press (traditional pressure gauge so different measuring mechanisms) within 5% agreement. For a YT video it should be okay. Cheers
Cool stuff. If I could understand it, I'd build spaceships instead of houses. If I have to 2x4s horizontally, I'll only span a max of 6ft. No knots, no twists, crown up, 12 inch centers. I can store an engine up there. Old school carps were artists more than engineers. Let the wood tell you what it wants to be used for.
Do they specify water content? Had to design a lifting and carrying system using materials only found in Bangladesh, and it blew me away how different the structural capacity of bamboo depending on water content. Not a carpenter (although I've done a lot of remodeling projects), so honestly don't have the experience. I did design a sliding floor, but I made it out of steel, since the span it had to cover was 8'x7'. Curious if moisture affects wood like it did with bamboo.
super cool video, I've been wondering about this since i, a few years ago I got into an argument with a safety representative about if I could use a 2"4" laid across a doorway as an anchor point for fall protection, the door opening was 90 cm and the requirement for an anchor point is 12kn here. I now know that although my solution may not have been quite 12kn, it was certainly more than enough to hold me next time i will find a piece of lbs
The weakest board that was tested had two large knots smack in the center. I know more than a few framers who would have rejested that peice of wook in a load bearing wall.
As someone who's done lots of wood and joint testing over the years I can say this is an excellent video. Small boards like 2x4s see structural use mostly in two cases, vertical studs/columns, and truss members. The testing in this video was based on Fb bending. This is primarily the roof truss case, where a board member is horizontal-ish in orientation and loads are applied along its length. Such loads can be from from the roofing materials, people, snow, wind, etc.
And yes, the values allowed to be used by engineers for wooden structures are very conservative and have plenty of reserve strength. Consequently, failure of wood structures usually occurs where wood is joined rather than in the wood itself. Bolts, nails, plates, glue, etc. are all used to join wood and the building codes have plenty to say about this as well.
@eyesonly4451 Thank you sir/ma'am, your comment is very much appreciated. It's also good to hear from someone who has attempted similar tests before. It's more to know that I didn't miss something instrumental. Many people comment about the use of 2x4s and that the test is pointless, but I think this conservatism extends to all sizes. I only tested 2x4s because my press can't break larger stuff😅. Cheers!
I learned a lot from an addition I recently made on my house. In California we use a lot of straps and brackets to home building. I'm assuming that really adds to the joining strength. Also, it had to be wrapped completely with 1/2 plywood and specials nails for additional shear strength. Seems like crazy over kill... But I feel safe in that room.
@@DoubleDoubleWithOnionsEarthquakes drive much of the building requirements out there. All the metal straps, special nails, and plywood are designed to resist motion induced shear loads that can occur during an earthquake. Such back & forth motion can rip a wooden structure apart at its joists if improperly built. Properly built wood and/or steel structures are the safest in earthquake zones. The worst is masonry construction, which can crumble like a dry cookie during an earthquake.
As a retired framer of 45 years who changed his college major from engineering after almost two full years (to psych and econ), I should mention 2x4s are specifically disallowed by code in floor and roof framing (at least in California). For decades 2x4s were used as rafters and chords in trusses, but now just the verticals as mentioned by eyesonly4451.
Another observation, that has little to do with the matter at hand, is the two photos @ 1:53. That may not be wood failure looking at the floor components. The way the floor fell, the separation of failed components from the others (the wood would split, not shear), and looking at the observable wood cuts leads me to believe it was something else like human failure (design, installation), though the second photo of the pair looks like there was some trimming of the floor joists in order to begin the repairs. I would love to know the stories behind those two photos.
Interesting video, thanks.
@@TheEngineeringHub If the point of the video is to point out conservativism in building codes, then ok, but you did miss the mark generally. 2x4's are rarely used in the scenario you were testing for. They are generally used in wall studs and therefore the use-case is in compression along its length where it can hold thousands of pounds. Out of that use case (framing walls), half the time they are not even load-bearing and are just used to hold drywall or doors in place.
A more useful test would be to test their compression strength by wood species and grades and some cases where they are bowed, twisted, and/or full of knots. I realize your setup cannot likely accommodate that though. The quality of wood products nowadays is junk compared to the past. Most big box stores sell you fast-growth yellow pine compared to the Douglas Fir I constructed my house from 30 years ago. In addition to them being very knotty, it is difficult to find straight ones with any consistency, and they are very light-weight in comparison to the past. Nevermind the dimension change from true 2x4 to 1.5x3.5 from many years ago. My first single-family home was a Sears home in Cape Cod style built in the early 1960's. It used true 2x4's as roof rafters. It will, no doubt be there still in another 70 years. The quality of the wood was very dense, hard, and heavy. Another useful test scenario would be to test true 2x4's to current dimensional lumber. You could see a significant increase in strength (in your bending test) compared to US dimensions and what a "mere" 0.25" makes in both dimensions. To make it useful to point out the affect of dimension on strength, you would probably have to mill several of each kind from the same log to make it fair as you cannot buy true 2x4's from a big-box store anymore as they would need to be custom-made.
I have never scientifically tested the strength of a 2x4 but I have used plenty as levers over the years, I can testify some are stronger than others!
Of course this is from nature. Nothing is standardized.
yes agree.. type of lumber, and even the age tree that lumber was cut into size.
many more factors surely
Yup, I've broken more than a few 2x4s and 2x6s prying stacks of lumber to one side or another
Typically (to european code) you should not use 2x4 for structural load. Anything rated C14 or lower is consider non structural and should just be used where structural failuers are not faital.
I work with a dude that tops 360lbs. He will walk 2x4’s with a loaded belt carrying materials
The illustration of all 100 potential 2"×4"s under the bell curve was really good. I wish more statisticians explained using that method, because I think a lot more people would understand the visual distribution instead of fighting engineers about the numerical one.
@k.jespersen6145 thank you jespersen🙏 I agree hehe
Now test an old reclaimed 2x4 from the 50's
@@m.5051 Question... mark...? My comment was in praise of the illustration of statistics. Did you put your response in the wrong place?
I'm a mathematical non-visual person (and a statistician). The numbers are all I personally need. But even some other engineers prefer to see diagrams. My struggle is that the same info that I can describe verbally or in writing in 15 seconds takes two hours to put together in a diagram. There's no real "answer" here except trying to find how to either describe it more effectively or to figure out how to put diagrams together more quickly. I've worked for many years on both, there's no perfect answer.
@Stephenwc well said!
Note that if you've bought 2x4s in the big box stores (HD I'm looking at you) they aren't even 1-1/2 x 3-1/3 but almost 1/8" smaller in both dimensions. So I built part of a project with one delivery then had huge problems because all the lumber was smaller. I went to the store intending to return the lumber I thought had been missing BUT found out everything they were getting had experienced 'shrinkflation' (like in the grocery store where the box is the same size but has less contents but the price didn't change, so you ARE paying more for less). I went to a couple other suppliers, found some older bundkes still the old size and bought all I could afford to stock & store for future projects.
But the point is that smaller 2x4 aren't going to meet the strengths the old ones did.
But that wasn't the problem I had, we built some walls with a mix of old and new lumber and the dimensional differences weren't noticed until the sheetrock was being installed, going fromba std board across to a narrower board then back to a standard board leaves a gap under the sheetrock at the narrow board and caused the screws to pull through there. Yes, crappy builders don't care and a double bay of unsupported sheetrock would probably last long enough for the warranty period to expire but that's not how I do things. Andvif you built a whole house out if the smaller lumber, tolerance stacking would throw off your prints dimensions eventually. So new prints would have to be drawn up? The mills aren't doing this on their own, the big wholesale outfits buyers have to approve (and maybe even instigated it to get more sticks of lumber out if trees so more profits?)
Also the fact that the new growth is harvested at a much smaller diameter could play into the push for another size reduction (just speculating, I don't really know) but the motive of higher profit margins is probably baked in. For now the high reserve strength seems to cover any potential cut on the dimensions.
@@TheEngineeringHub yes on the strength but it really does create problems when your using material that's smaller than specified. If a wall is thinner because the boards are smaller, will prefabricated window boxes fit? Code requires that utility lines holes through studs have a certain amount of wood left on each side, I forsee some inspectors who are picky failing some installations (sink drain lines running horizontally through a std wall pretty much have to be centered to leave enough wood on each side for compression strength support, i didn't measure but if the line was just offset slightly with the smaller stud then it wouldn't have the code required measurement.
@@bobjoatmon1993 oh absolutely! So many issues with mismatched lumber. I was not disagreeing with you: I was just adding a thought. Cheers
The big box stores absolutely dictate size.
I have an older house like 100 years old and the two by fours are real full dimension 2x4 inches. I was shocked at what passes for a '2x4' today. Not even close in deminsion
I have never had an engineer call out a 2x4 for a floor joist. They are insufficient for both strength and insulation. But probably a great reference for testing since they are the smallest structal member used in a residential home.
You would need an engineer to design a floor system with 2x4's. They used to be included in span tables, way back when when I was using UBC. I'm not sure if the IRC ever included 2x4's. But, they are sufficient, and you can even have smaller lumber engineered within a floor joist system. There are a lot of variables. Common species like SYP are weaker than Douglas Fir. The number of members per joist, span, spacing, deflection, lumber grade, loads like live loads, seismic loads, shear loads...all play a part in the design criteria.
The tests done in this video were likely performed on stud grade lumber. That is, lumber that is to be used in vertical position. It doesn't carry a number grade, and I don't really know the comparison between studs and say a grade 2, but I do know a stud would not be as strong as a grade 2 piece of lumber. The standard in most codes is number 2 or better. Although, the IRC allows the use of #3 graded lumber without the interjection of a structural engineer.
I built a deck with 2x4 joists for a 5ft span. There's no code applicable under 6ft.
Shed floors in 10'x8' and under are often 2x4s which were done by an engineer. Course they aren't a living space load and having a springy floor isn't a big issue in a small shed.
@@Cragified you can also pick up strength with blocking or using 5/8" - 3/4" plywood on the floor, instead of OSB. There's not a whole lot of code to shed building in most areas.
@@Cragified Exactly. And most people building a backyard shed are going to throw a few cinder blocks under the floor beams to massively decrease the amount of spring in the floor.
C14 is not allowed for load bearing structures here in Norway (I guess that applies to other European countries too). C24 is what is used for house building.
In the UK we use either C16 or C24. Also, 2x4 can slightly vary in size - 44-47mm x 95mm
And funnily enough the dimensions are 48x98mm in Norway, I.e. the "biggest " 2x4....
@@arntoveh75 Lucky you! I don't so much care about how large these 2x4s are as I wish they were more uniform. CLS timber here in the UK which is the american style 2x4 (38x89) is more consistent than the UK style 2x4 which is supposed to be 47x95, but can be 44x93 or god knows what else. I wish they would make them all 44x95 and make them consistent like CLS.
Can I ask why is wiring on the outside of the walls here 😩
The code assumes proper framing procedures which rarely occur. Most of the framing I've seen in the last 10 years makes me afraid to walk into the house.
very true, the code has to account for all sorts of practices and construction shortcomings
Everyone keeps saying "they don't frame/build them like they used to!" Bro, the post ww2 baby boom housing was way worse. Older houses just didn't have a youtuber content creator walking through with a magnifying glass trying to generate clicks.
No woodworkers that knows his stuff and cares, would have used that beam you break at the beginning with that node in the middle. Got to read the wood and recognise the weaknesses.
As the strong and weak side. Sometimes discard. Sometimes turn it the right side. Not an uniform product. Got to know the material.
@@JeremyBell idk man, plenty of older homes have their problems but I see plenty of brand new construction where thousands of pounds are held up by an inch of air and about 10 nails because people cant seem to get their cuts right. it's just geometry
As a builder for over 30 years. I myself and nobody else in my experience has ever used a 2x4 horizontal in a structure. Used as a vertical only,
The same thing is valid for 2x8. And also we never use C14 graded wood for bearing constructions.
Watching US and CA videos about timber frame building was quite shocking for me tbh. My first thoughts we like "is it really legit?". In Europe we use C24-C30 graded wood for frame walls studs. The material has a smooth surface and rounded edges, so an insulation slides inside with no resistance and has a smaller contact area with plaster board. Vapor and wind membranes are taped, so the construction is tight. In US videos I see a raw surface of studs with unequal profile, the insulation is just pushed in like no one cares and nice finish outside. Why so?
I did, cheaped out on a wood pile cover, very small slope, 2x4's on 2' centres across maybe 8' span with steel roof. Live in a heavy snow load area. At least one of the 2x4s snapped under the spread out load, must have been over at tonne up there, so I eventually reinforced a few with 2 x 6s. Since it's not life or death I didn't care about collapse, but was actually surprised it held up almost a decade with so little damage. Wood is strong!
@@AlekseiSljusarev Because like our incoming president, we're all about flash not substance. lolcry please save us.
@@samntv-jt5mm irrelevant
@@samntv-jt5mmyou are exactly how I imagined an idiot would be. Were you crying and screaming like all the rest of your like minded peers?
here in England you were only able to use stress graded timber in the construction of a dwelling , it was stamped by an inspector and clear for all to see , they got rid of that rule some years ago
EU took your stamps
In Sweden, the smaller dimensions are wood that has been planed. If the plank is sawn, it has larger dimensions. We use the metric system, but I use inches when it comes to lumber. I say, "Two inches Four" and if the plank is planed I say, "Two inches Four planed"
Yeah, 2x4s were the full 2" x 4" pre-war and not planed, so they were rough sawn, here in the States. Then there was a period of a few years when they were 1-3/4" x 3-3/4", finally becoming 1-1/2" x 3-1/2" and fully surfaced and planed. If my memory serves, they may have begun the transition right before we entered the war, like '39, '40, or '41. We can still order rough-sawn dimensional lumber for design elements, and the older guys (I'm raising my hand here) will still order our larger pieces (6x, 8x, etc.) by appending S4S, for surfaced four sides.
I never found a definitive reason why the transition was made, but I am assuming much had to do with cost savings (8X volume versus 5.25X volume, a full one-third savings) when people realized that vertical members did not need that much mass with the load they were usually carrying, along with the more pleasant smooth surface.
I could go on and on, but I'm sure I've bored to death more than just a few.
Interestingly, we right across the sea from you, in the Baltics, calculate with the same Eurocodes, but wood here is in mm, e.g. as 100x50mm (not even 95x45 as in this video)
Lets not forget often too, holes have been made to have cables have been run through parts of a board
cable sized holes drilled in the centre of the beam,
should not decimate the beams strenght
(the beam top is subject to compression,
the bottom to tension, in the centre those forces should be in equilibrium)
@@laus9953 but you are reducing the amount of wood on either side. Usually the holes themselves are larger than the cable or pipe running through them as well.
@@Ultrajamz That's accounted for in the code books. There is a max hole size and spacing per style of joist.
Holes on neutral axis are of low effect on the beam strength it's a bd³/12 thing...
My house was built in the 1950's (US) and all the lumber is dimensionally 1/4 inch taller than what you would find on the shelf today. The growth ring patterns are very tight ("old growth"). If you're ever demo'ing old growth structure and are able to salvage any of the wood for reuse, it's worth it. None of what they sell today will match its strength (even holds screws and nails better).
first class explanation of complex area, learned a lot, thankyou
I appreciate your effort and methodology on the testing. Very well done.
For the record, any contractor who uses 2x4's for flooring joists should be in prison. 2x4's are good under compressive loads such as vertical wall framing, spaced close enough together to well exceed the loads encountered. NOT flooring joists.
Fair point! Just to clarify, I think this comparison extends to all lumber sizes. I tested 2x4's because my hydraulic press would have hard time breaking 2x6's or larger😅
I just used 2x4s for floor joists :(
It was for a shed though :P and they spanned at most 4 feet :D
It would be perfectly suitable if the span is narrower (in the video it's 2.4m) and if you double up on the spacing, so nothing against a 2x4, it just depends on the usage.
The code book 8:34 tells you the maximum span allowed for each size of joist being used. 8:34 @@robertrjm8115
I’ve never seen 2x4 as joist, so you don’t need to worry about that. This test is not about verifying this type of lumber for that purpose…
My house is 150 years old. The wood in it is just nuts. It would never pass code today, but it’s still standing. It probably has 2x more wood in it than a house built today.
In addition, the wood used probably is not from a fast growing industrial type of forestry (spruce) but a naturally grown broad leaf wood which is substantially stronger than fir or similar used today.
@@robertrjm8115 the floors are 3/4” by 4” oak on top of 1”x6” pine sub floor. The supports are whole log pine. Everything else I can see has been pine so far. But it is different. It has age hardened, but the grain seems more dense as well. All of the spans are different as well. Seems to be around 24” on center. Every project is like an archeological dig. I find all sorts of strange shit buried in the yard. Found an entire chimney once.
I've found that really old 2x4's can shatter. It's like the sap has dried out and there is not much holding the layers together. I can take a hammer and knock a stud out of the way, and it will splinter into pieces.
The fact that it's still stand and probably solid af is a testament to thos who built it. Craftsmanship, integrity, and quality are a thing of the past. These days you pay $1M for a house built with OSB, cracked roof trusses, and wet studs....but it all gets covered up with high end finishes so it LOOKS fantastic.
It's like polishing a turd ffs.
@@OU81TWOnot all of them, I replaced a furnace on a 10 year old house once were the main floor of the house was doubled up 2x12s that were run 12" center to center. I went into the basement and looked up at all those joists and I was floored. You could drive a semi across that floor.
As a builder w/ 45 years I'm glad that code factors for the lowest common denominator.
I've been subscribed for quite some time, and appreciate your unbiased opinion. 👍
I work at a place specializing in reusing old wood. The 2x4s are actually 2x4. The grain I see are from much larger trees. I am also amazed at how straight the old wood is. Even hand hewn is amazingly straight compared to modern lumber. Great video
I was involved in a project rebuilding a four story mansion built in 1903. It was completely dismantled and trucked 1500 miles across a little of Canada. I spent a month in a field sorting out a couple of tons of Italian terracotta brick that trimmed the exterior. Over there was the 2x4 framing. They used single pieces on the exterior, 30 40 feet long, straight as arrows, full 2x4 fir. They didn't use it because you couldn't drive a nail into it.
Tgis video is very educational. I enjoyed it and it’s good to see how wood can hold depending on how much force is on it
"You may argue it's stupid to design structures for the weakest link" which seems like a good way to invite the universe to drop a building on you.
Just to make it clear if the universe is listening: "No universe was invited in this video"! 😅🤣
Yes. If you will pardon the pun, your statement at the end that the quality of the carpenter ,,, You nailed it. You also tested four 2X4s, at least one of which was strictly a No. 3 grade. Size of knot, type of defect, position of the knot or defect.. A good carpenter accounts for all of these. If there are two elements that are bowed,, I will combine those elements in oipposing directions. If the knot or defect is so large the grade should have been a No.3 or No.4 that IS the element I will use for cut up blocking. Or,, I HAVE been known to over order on the basic stock just so I can reject pieces that are substandard. The load or bunk is unbanded in the front yard, and if an objectionable piece is encountered, It is simply placed in a returns stack. I will not use garbage.
# 2 should never be stamped at the; Mill for a #3 or worse.
Standards set, when deligently applied and followed always worked. Should not be your job too grade what already was suppose too be done. If that was required, then they could let go the grader and reduce the purchase cost. ACCOUNTABILITY!!
@@edwinlipton Edwin, your faith in the grader or system is misplaced. Yes, I have seen nearly flawless grading and the bunk ( a bunk is a banded 'lift' of 2X4s approximately 360) received was of superlative quality. However it has also been that I have received a bunk that would barely make dunage or pallets.
2X4s unusable in any wall and 2X10s or 2X12s with large knots in the edges, trash.
The real world and jobsite contracting can be exceedingly ugly. And, If I halt the project because of poor delivered materials, it is I who pay the penalty. In lost time, wages, and even the job when the principal contractor just hires someone with less integrity, and I lose the job all together. (In which case, I don't want to work for him at all.)
@Sailor376also I know the exsperience. I too was a Mechanical Lic Contract Plumber for 17 years of a 27 year career. Cut short for no other reason than Physical health "bones". So I understand what your up against. Once was a time when "we" only had too do our desired trades with learned skills and focused attention for a decent profit of reward. Now however,, youve got too do everyone elses job to get your contracted job alone completed. Including regrading lumber quality and that General contractors slice of pie as well.
For me; it was poor quality in mass produced "nibco" copper pipe no longer produced in the U.S. but south in Mexico. They'd bunndle it up for mass shipping with steelbanding, so tight and stacked so high that it egged and mared it too where a round nibco fitting could no longer join the pipe to fitting without alteration by a pair of channel lock pliers slowing down the water pipeing process. Nothing one could do about it but bitch and accept. It was due too profitization and production cost cutting. ie, cheap Mexico labor and utilization of Mass over sized loads of copper being transported. I worked through out the western states, same everywhere. Big, small, tracts, industrial, institutional, commercial retail, or stick built customs. Everything but sky scrappers. Wanted those. But never got too.
Loved the trades. Building was more than a paycheck too me. Broke today because of the shysters taking the profits who knew absolutly noting about building, but knew how too profit. Boy do they!
@Sailor376also ya mis understood me. I have NO Faith in mass production at all. It is profit driven and the reason for Boeing's demise. Planes dropping out of the skies, Star liner debacel and my once belief in the Big 3 autos now producing over priced junk.
@@edwinlipton Big 3 ,, over priced,, Yep! It was as recent as three years ago I came upon a dealer with a loss leader for an F-150, 19,999,, Of course he did not have one in stock and the upsell began. And I nearly, and should have cornered him to order and produce the 19,999. I just need a truck,, no bells and whistles, high school girl toe nail sparkle pink and blue tooth everything,,, all absolute junk if you are going to throw lumber, bricks, and blocks in the bed. Current price is doubled,, in three years 39,999 and there is not a stripped down pickup anywhere, 60k to 120k for infotained 6 cup holders 12 speed auto, 3 cylinders and blue tooth start the truck remotely from the next city over. JUNK.
My most recent disappointment, insurance. I took a good 2009 with exactly the engine I wanted, and rebuilt it. Paid 4.5k now into it for 14.5k The insurance will not cover it. Their position is that it is just and only a 2009 and worth 2500. and they want to charge me 1000 per year to cover that 2500 Time to go self insured. BTW Fun to discuss with a fellow contractor. Thanks !
Really nicely designed video! I especially liked all the documentation inserts. And the graphics on the Bell curve @8:15 was chef’s kiss. Cheers!
Having been in the trade for over 40 years and from design, specification and engineering there are a myriad of specific specie, grades, and grain orientations that will dictate the performances capable for framing members and their respective loadings and uses…we have used 2 x 4 stock for mezzanine floor joists to reduce heights in low headroom instances, spaced rather closely 12” oc and 8” oc yes this is atypical but it’s still there some 35 years later and was used for static loads.
Despite some of the comments here - I'm actually extremely grateful for this video. A lot of folks or talking about "there's a knot there, therefore this is not legit" BUT the reality is most 2"×4"s at the big box stores or numbers will have lots of knots. I "overbuilt" an outdoor sectional for the family sacrificing aesthetics for something I know people can jump on, put all their weight on or whatever without ever having to worry that one of the 2"×4"s would break. After seeing this video it reassures me that it doesn't hurt to play it safe.
What ever the dimensions and species, the grade, etc, the engineering is done from simple tables and they tend to be quite good. I've never had any kind of framing failure in 55 years. And I'm still working, too! The 1.5" x 3.5" has not changed for many decades, I think since 1964, when I believe it had been reduced from 1-5/8 x 3-5/8," and it had been that for decades. And people are STILL saying, "You mean its NOT a REAL 2 x 4" ?! No ma'am, its a sort of funny deal we get from the lumber companies. But I assure you they are entirely adequate." Now of course we use 2 x 6, if you can handle the nomenclature, and we went to 2 x 6 to accommodate more insulation, also an old story. The whole thing reminds on of other questionable dimensions, but lets not make this more complex than it is.
Nice video man, excellent explanation
In Norway a 2x4 is 48x98mm from the store. Dimensions are round numbers minus 2mm for lumber. Glued laminated timber have other numbers in height that are typically rounder. In Ukraine a 2x4 is 50x100, but is green and not kd.
Stud material is meant for vertical applications in a wall diaphragm, not to be used as horizontal framing members. Therefore the load is applied through the longest axis, not either of the shorter two. Also they gain ability to carry VERTICAL load by the addition of sheeting systems, both interior and/or exterior. Usually stud material is an inferior grade of lumber from inferior tree species such as spice, pine or fir. The only times I ran into specs for using structural lumber in stud applications were when the walls were above normal height. For example, building an addition onto a shop with 16 foot side walls the engineer specified 2x6 MSR studs. That’s Machine Stress Rated.
Structural dimensional lumber is higher quality and meant to be used in horizontal load applications such as headers, beams or floor joists. It’s not only made from better species of wood, such as Douglas fir or larch, but also graded higher by visual inspection.
The code books have tables to reference that give a designer guidance on acceptable spans for different dimensional lumber sizes, types and spacings.
Suggestion: do a stress comparison between a 2x6x8 stud grade and a 2x6x8 Douglas structural lumber. I think that would be more educational to the average person who goes to the home improvement box store and doesn’t know what piece of lumber they need for their project. Stud grade lumber shouldn’t be used in horizontal framing that experiences a vertical load.
The correct answer is "none" because 2x4 are not sourced from wood that is used for making beams, they're for compression longitudinal loading. You can simply walk down to the local wood pile and discover this with a small screwdriver: they weigh about 18% less per board-foot than actual beams do!
A properly engineered building does not use horizontal 2x4s to carry loads . The wood is strong in compression not bending .
Go up into your attic, or into a multi-story apt complex's cieling. You will 9 out of 10 find engineered truss framing, or floor joist girder engineered 2×4 support joists supporting the next level with 3/4" sound deading lite wieght concrete poured for the units. It's materials and engineered application that make the difference. Use rubber if you will,, with the right engineered application,, it will stand.
1:53 Those are not broken joists. In this case, the mode of failure is pretty easy to see. They did some kind of poorly made scarf joint on that floor.
Graded C14 apparently - I have never seen anything less than C16 in the UK and C24 is pretty common. Looking at those C14s, I wouldn't make a chicken run with them.
I bought the wood in Denmark and I would say most of the lumber (at that store at least) was graded C14 as you can also see in the video. I'm not sure if the graders are just being overly conservative because the yield stress was way more than 14 MPa although the boards did look very poor on the outside.
@@TheEngineeringHub Many thanks for the reply. It's a long time since I did the sum but if you take the text-book figures for the tensile strength of pine you get far higher ultimate load capability than the ratings. Also, the degree of pessimism applied to, for example, roof structures seems to have increased considerably over time. Some years ago we had a garage roof replaced. The original, some 70 years old was a corrugated iron job supported by 2 x 4s at a considerable spacing. Its demise came only after a considerable period with the sheeting rusted through in places. Its replacement, to modern regulations, included a 10 x 4 cross-beam to halve the span and 6 x 2s at about half the spacing of the original 4 x 2s. I did wonder if they had stressed it to allow the car to be parked on rather than under the roof.🙂
@@ColinMill1 I was told that old timber was stronger per cross-section than modern one because it tended to be more slow-grown and hence denser. I am in the middle of refurbishing a 90 year old house, and I can tell you that the 90 year old 2x4s that I am removing are noticeably heavier than the new ones I am putting in.
@@chrisgemmix0815 It's possible. I have just measured the density of some new offcuts here and 480 kg/cu.m which is in the middle to upper end for white pine but there are plenty of pine species it could have been in the past that are denser. One thing that is different here is that, going back 60 years 2 x 4 sawn really was 2 inches x 4 inches. These days it's a good 6mm under that in both directions. Even allowing for that the regs do seem to have gone extremely pessimistic over time.
In Norway c14 is not allowed in load construction, min c24, assumed the same in Denmark.
I am not an Engineer, so most of this was over my head...but none-the-less interesting and useful information. Thank You
yes, more videos about complex sub aspects please !
and like another commenter wrote - would be fantastic to see very old recovered beams tested for strenght comparison !
My father in law was an aeronautical engineer. He'd visit and work on our house and when making plans he's spend a day covering pages of paper with structural calculations. Finally, he'd say "but never know how strong this particular 2x4 is, so let's just use a 2x8". Everything ended up strong, but heavy, but at least it didn't have to fly.
Retired engineer. I weigh 205lbs and would never step out on an 2x4x8ft spaning past 6 feet.
Excellent video, Steve - all the tricks you've developed over the years -- like holding back some of the part C -- are invaluable for us DIYers so we don't have to learn the hard way! 👍
Dimensional lumber varies so much. My old house has 2x6 floor joists spanning 16ft at 24” on center. They are old growth pine and are so much more dense than new growth. The rings on a crosscut of wood are super close. I’d love to test their strength
I would heavily suggest reinforcement of the floor. That is well, well over the load demand of that lumber.
My old house has 3x12(not planed) as for joists 12" apart over 16' span and I think that's just over what's required.
My house was built in 71', 2x6 @16" oc, 16' spans. I went under the floor and poured concrete footers mid span and ran double 2x12 beams perpendicular to the 2x6 to support them. I've been a framer for 25 years.
It's as much about the freedom from knots, the closeness of the grain, and the species of wood as anything else. With 45 years in building the framing wood I was taught to cull out for returning is now considered to be adequate for milling trim. There might be 10 good studs per bundle now, with the rest being substandard. That's why the N American acceptable loading is so low; our wood is crap.
Yes please, make a more detailed video on the rest of the coefficients you used to get the load capacity of the 2x4 in single point bending.
Love these videos. Now for the questions.
Can you purchase a 2 x 4 with no knots?
I would guess using a wood with a higher Janka rating would be better.
Both probably costly
That’s a unicorn
Higher lumber grades have fewer and smaller knots, but you're definitely going to be paying more for it.
@@JosephBears Ok, thank you.
The piece of wood you have between your press and the beam is spreading the pressure out, which the standards authority tests might not do? (IDK, just noticed this, that's all).
I suspect the same, it probably helps distribute the load and achieve a slightly higher capacity. But I don't think that it would help more than a few percent, max 10%.
It is a very good thing the actual strength tends to be much higher than the code values. Seeing boards made into Swiss cheese with penetrations and knowing the torsional and sheer forces from high winds and the incredible static loads from snow and ice those conservative numbers are the right ones to use.
Would love to see a video going through all the different equations in a comprehensive manner.
Awesome video. You should try it with a true 2 by 4 sawmill piece that ridiculous laws says we can't build homes out of. Or oak piece to.
Nice presentation! The 2x4s did better than I thought they would.
In my region in Canada, some lands are planted with Norway spruce because spruce is well-suited to this area, and Norway spruce grows faster than native species. The purpose of this was originally to supply the paper mill in my city. However, the paper mill has been closed and demolished for over a decade, maybe even two. Landowners with these trees now struggle to sell their logs at a good price because this spruce isn’t high enough quality for dimensional lumber and stud (at least or canadian and american stdards). Maybe that’s why a 2x4 is a bit larger in Europe? I don’t know if that has changed; I had some wood cut on my land a few years ago. Luckily, I didn’t have any Norway spruce.
Interesting to see the dimensions of a 2x4 in other countries. In Australia, it's 90x45.
Kinda. Go down to bunnings with some callipers and try and find 2 pieces with the same dimensions
I am an European structural engineer and using EC5 in my work. There is such a country in Europe like Norway, whey have their own building code. Every time I design a timber structure for Norwegians, they claim that all ridge beams are so much over dimensioned. They use lower coefficients in their calculations and beams and joists have significantly smaller cros-sections. SO there is such a joke in our region, that as soon the wood crosses the Norwegian border, it feels Viking power and becomes stronger.
That was a reassuring test, thanks for sharing that content!
Anyone that does remodeling of houses from 75-125 years ago can attest to the fact that lumber is way stronger then people think.
Ive seen some seriously undersized framing by todays standards and those places havent moved, sagged or shifted an inch in 100years.
This is very interesting. I would have never put myself through the torture of reading all those code books! lol
Does the code describe when the 2x4 colapses or it's maximum safe load?
I mean, I'm not a structural engineer, but as far as I know, they have something called 'safety factor' or something like this, which changes depends on the application.
In some application it can be 2 in some other it can be 5 or more.
eg, if that board failed at 500kg load, then can be used for predicted load of 250kg in flooring (factor 2), but only for predicted load of 100kg for a bridge (safety factor 5).
btw. those factor values are just random numbers, to describe my idea.
I think I remember "allowable stress" for wood is the 5th percentile strength value/2.1.
I would love to see a test of modern 2x4 compared to actual 2x4.
I never seen C14 for sale in U.K. C16 and C24 are grades normally stocked by building merchants
Studs used to be straight grained, good wood. Not so true nowadays.
This is why 2x4s are never used for floor joists. I'm unaware of any jurisdiction in the USA that allows anything smaller than a 2x8. Wuold love to see this test repeat with and without pressure blocking, and bridging mid-span
It also depends on the diameter of log that the 2X4 was cut from, grain orientation and different stress loads that are applied in various applications.
2x4s. Are for sheds and interior walls.. maybe just for the burn pile the way they are these days.
Really cool comparison of code capacities and actutal test results. Keep the great content coming!
Do you know why the eurocode chose not to include a short term loading factor?
direction, different section of the tree, humidity, all can affect that 2x4's capacity, but those nodes are to be avoid at all cost.
It would be interesting to see the strength of them turned the other way. I know guys make temporary platforms with them, I always questioned how safe it actually was.
Great animation there.
and this is why you don't use 2X4 s for live loads.
Span is crucial in this capacity. Here it was apparently about 90 inches
Could you make a video explaining shear strength for residential houses? In particularly if using OSB vs Termo-Ply or similar Structural Sheathing with 2x4 framing? My house is built using this in North Texas and I have always wondered what the strength breakdown would be actually vs what is in the Dr. J evaluation report.
For whatever it’s worth, home building in the US can vary widely from region to region. I grew up in a very rural county and they STILL don’t have any building codes there; the only thing you have to get permits and inspections for are wells and cisterns.
That said, as I understand it, most average sized homes built these days in the US use engineered floor joists and engineered roof trusses as well. 2x4 are more used in vertical applications in the general framing process.
I’m definitely not an expert, but those have been my general observations.
They have NO building codes at all? I don't know how people get insurance then.
@@justayoutuber1906 The whole county literally has zero zoning or land use regulations. Also in Colorado, no state wide code other than for schools, state owned buildings, and multi-family.
It's an extremely rural county with only 3300 people in a pretty large area. Poverty level of 19 pct. population of 1.4 people per sq mile.
Not surprised the tests are so different. We're dealing with natural resources that are hard to standardize. Wood can be very inconsistent. These tests are useful, but it's rare you use a single 2x4 in isolation. Also, 2x4s are never used for floor joists, only for wall framing.
In Florida we have been getting a bunch of lumber from Europe the last few years. I guess beetles were decimating the forests there, so the decided better to just go ahead and clear the forests and sell cheap. This lumber looks like you would imagine a dying forest could look like. It looks like the trees were sick.
Awesome content! Nothing like it on youtube and would love to see more. Thanks
More to come!
it means a person who can deadlift 500kg can also break a 2x4 wood by applying an upward force
hahah love it! I would love to see a YT video of a dead lifter attempt that
Hope they don't get their eyes poked out when it breaks.
Great video and demonstration, love it.
Technically you did not test a 2z4. You tested a beam less than 1.5 x 3.5 inches if a US standard because of the knot. The knot on the edge reduces the actual strength dimensions of the board at least by the dimensions of the knot. And the length of the beam is important because longer = weaker. Just some thoughts.
Wow I have always wondered and honestly subestimated the might of the good ol 2x4 I'm impressed.
I have tested thousands of pieces of solid lumber and fingerjoined lumber in various ways. Tension, bending break tests. It is pretty crazy to think a high grade 2x3 fingerjoined lumber can easily handle over 20000 pounds of force in a tension test before it breaks.
safety factor is a reason it's set lower
The thing that always scared me at looking calculations with wood when I was in school was at school was species and knots. After doing woodworking as a hobby for a few years, those are kinda non-issues (for construction lumber you don't really get a choice with species, and just avoid knots). Grain orientation should also matter for how the load is applied, everything in the video looked like flatsawn pieces but if you go though a pile, theres a handful of quarter sawn looking pieces as well.
I also question the values in the code, if they are using numbers measured in the early to mid 1900's, it is likely that the wood they measured is not what we are using today. Today's lumber is farmed and optimized for growth, that means farms want the tree to grow as fast as possible so they can harvest it and grow the next crop. Since tree rings are made at a constant rate the spacing between rings is much larger in farmed trees compared to trees growing naturally in a forrest. Old growth trees starved in their early years, they grew in the shadow of mature trees and would have took much longer to get to the same size thus their wood would have many more ring per unit length. The rings are what provide the strength and durability, and if what was measured was old growth wood that has 5x the density, it would be almost an entirely different material.
@bryanthiga3198 I love this comment. I actually looked into that very issue and made a video about it about a year ago. You may like it as well. If you end up watching it, let me know what you think. Cheers
It appears the weakness of 2*4s can be easily remedied by reinforcing the center with a long metal plate on both sides or use glue, fasteners and wood.
Excellent information. I rebuild my own deck with 2x6 framing. I over engineered the crap out of it for good measure. With this information I feel even better that I can drive a tank on it without issues😂
I would love to see this with 2x6. I recently built a bridge that is 36 feet long and 6 feet wide, with 4 2x6 per beam and 6 beams.
nobody in the US is using 2x4 in a floor system
Right. Plus, many framers cut the worst ones up for blocking and furring, and carry zero load
Your ceiling is a floor system.
Definitely not in 2024. I’ve seen them in older buildings (which is wild).
@@TheOsfaniaIf you weigh 300 kg not only will you not be walking in the attic but you will not be even walking to your damn fridge
An 8x2 could’ve been a more helpful for this.
Did you use the correct die to do the test? that board which the gauge seats seems that is helping distributing the force
@tuzzogetti Yeah, I started to suspect the same since all failures happened on the tension side. But I had already started with this setup, so I continued this way. It could be helping for sure, but it wouldn't be a huge contribution I don't think.
Where I’m from in Canada, my load bearing framed walls are never 100% touching/bearing. IMO this is why code exists to factor in mistakes in framing and variance in quality of wood being used.
NDS by American Wood Council is a banger. Great publication.
Woodgrain, wood type, growth rings and knots, moisture content all play an important part. Knots are weak spots.
Good video. It's a small amount of accurate information. People who argue should simply add it to the other information they already have do their own thinking and stop asking for someone else to answer every question.
This is good example about statistics. With that large variation, it becomes obvious that the distribution extremes are pretty far apart.
I'm a bit concerned about using the load cell in this way. The force should go in the threaded holes, not distributed over the whole face.
@MichielvanderMeulen I calibrated and tested the cell extensively before the experiment. I am comfortable saying that it matched with the loads displayed on the press (traditional pressure gauge so different measuring mechanisms) within 5% agreement. For a YT video it should be okay. Cheers
Probably different load combos in Europe too. NDS does have a finagled version of LRFD, but pretty much any designer will use ASD.
Good testing. What about compression end to ends what is the breaking point?
Cool stuff. If I could understand it, I'd build spaceships instead of houses. If I have to 2x4s horizontally, I'll only span a max of 6ft. No knots, no twists, crown up, 12 inch centers. I can store an engine up there. Old school carps were artists more than engineers. Let the wood tell you what it wants to be used for.
Any modern joist table starts at 2x6 for a reason. Sill impressed a proper 2x4 could support so much
Those knots sure help.
New growth vs old growth would be interesting
Your little block that you have under your load cell will make a big difference in the load that the wood breaks.
Do they specify water content? Had to design a lifting and carrying system using materials only found in Bangladesh, and it blew me away how different the structural capacity of bamboo depending on water content. Not a carpenter (although I've done a lot of remodeling projects), so honestly don't have the experience. I did design a sliding floor, but I made it out of steel, since the span it had to cover was 8'x7'. Curious if moisture affects wood like it did with bamboo.
In the construction world, this is like saying, ' I discovered air'...!! 😂😂😂
Aren't you supposed to a C24-grade for construction? These are usually better cherrypicked ( and a bit more expensive)
Seems like C14 is already hella strong 😅
on average (key point)
super cool video, I've been wondering about this since i, a few years ago I got into an argument with a safety representative about if I could use a 2"4" laid across a doorway as an anchor point for fall protection, the door opening was 90 cm and the requirement for an anchor point is 12kn here. I now know that although my solution may not have been quite 12kn, it was certainly more than enough to hold me next time i will find a piece of lbs
Need at least 30 samples to really draw a statistically satisfactory conclusion. Still good video illustrating the concepts!
The weakest board that was tested had two large knots smack in the center. I know more than a few framers who would have rejested that peice of wook in a load bearing wall.
Mechanical engineer here, and I'm always looking for something for these numbers. Hobby building.