hi robin, could you use a flitch beam instead of a steel . my floor spans around 6 meters and can you use it as a sister as you can only buy 4.8 m timber thanks.
250 mm x 100 mm is only a 4x10. Which 2 2x12 boards glulam together exceeds whats needed. Which is around 50$ per 16 foot board here. And a quarter of the weight of steel. A timber frame don't need fire suppression here. A steel beam collapses under it's only weight in 15 minutes at 1400*F. The wood beams take over and hour. A steel beam here is around 100$ per foot. Meaning 2 steel beams is more than I spent on all the wood for 24x24 foot skillion cottage rising up 24 feet including roofing.
Is there a table somewhere than can help with determining what size steel beam(s) would be needed to replace a 16height x 3.5 inch width (a doubled 1.75) x 25ft long LVL beam? I am even open to having an additional steel support if necessary.
Cheers Robin, very informative as always! Could you do a video on when you choose a UB over a lintel? I'm used to seeing brickies using PCC, steel box and steel cavity lintels where I'd have thought a UB would have been required due to spans
@@RobindeJongh Cheers at very least it would be interesting! I've seen what must have been a 4m cavity lintel installed before and that can't have been leaving much of a safety factor!
@@MJWhelan1 The lintel suppliers have a trick up their sleeve, which is that they increase the lintel depth and steel thickness the bigger the span, even though they call it the same lintel name.
@@RobindeJongh Completely appreciate that the depth and thickness have to change to accommodate the increase in length and load like all beams, guess I am just interested in if there is a point in the calcs/decision making process that a lintel is determined as more appropriate than a UB?
Hello Sr. I'm planning to build a patio cover that measures 7meters by 3.5 meters I would like to use an I beam 7meters go to put wood beams on it .would you please tell me what kind of measures I need on the I beam for this proyect.? I may put 2 500 lbs. Thank you.
The timber beam section modulus of 4168 can be achieved using only TWO 250 x 100 beams, stacked vertically. The extra height of the stacked beam is not a problem in this attic. However attaching the joist at 90 might be less convenient than onto the steel beam.
I believe you can achieve even better stiffness and load bearing capability with a more elaborate truss design, using an even lower volume of wood. Granted, it's much more work to build a wooden truss than to just slap a steel beam in place. Then again, a steel beam on an exterior wall always significantly reduces thermal insulation properties (i.e. enough to feel it in your wallet), compared to something using wood, unless you build up the insulation.
....just making the point that two beams stacked on their narrow sides improve the section modulus by 4 times. i.e. the square of the height/depth increase.
I think one of the main limitations of timber is the deflection that occurs under live loading within permissible stress, sometimes to an extent that results in cracked plaster etc.
Hi John. Just a thought, I need a ridge beam for a project. I have many 200 x 50 timbers that were spare from another job. Instead of using 2 side by side and bolted could I use them on top of each other to make a 400 x 50 ? I would aim to mechanical fix and glue together but more importantly to clad both sides with 12mm plywood glued and screwed to prevent each timber moving independently. Not allowing for any strength the plywood gives where would this timber, 400 x 50 sit in your timber calculation table as they only go up to 250mm ? Thanks
What about if you used the timber in a timber frame structure (similar to ladder horizontal ) then screwed and glued both sides , so you get the depth . This could be constructed on site and would be far easier to handle that a large steel girder ? ?
Interesting thanks. I see a lot of discussion on whether to use timber or steel needles when propping walls above for steels to go underneath. Maybe use could compare the strength of those?
You want the higher tensile material farther away from the neutral axis. So two steel plates with wood in between could maybe be viable. The wood would act like the flange (or web) in an I beam. The wood would be under shear stress and the steel would be under compression on top and tension on the bottom. The wood and steel would have to be bonded together well somehow. It is no good otherwise.
Thank you Robin Can you do a video soon on Units I have always struggled with conversions like cm^4 to mm^2 And how to cross off units above and below the line ( if you know what I mean) Thank you for sharing your knowledge and for the tables . Kind Regards, Peter
For a residential second floor joists how much can I span 2"x6" (with 1/8" web thickness) mild steel I beams at a 30 sq ft live load and also 40 sq ft live load? Thank you.
Why do you not factor the UDL on the timber beam calculation like you did with the steel? By the way, fantastic video, thank you for showing all the steps. Very helpful!
Thanks - glad you liked it! Steel design to BS5950 is "limit state" philosophy, so you factor the loads. Timber design to BS5268 is "allowable stress" philosophy, which means the allowable stress for the material already has a factor of safety in it. Confused yet?!
Using British Standards, we use allowable stress, which hsa factors of safety built in. Eurocode has changed this to limit state design, which uses a figure of ultimate stress.
Robin; can you explain the difference between steel and wood beams when it comes to nothcing, drilling holes etc? Does holes and cut-outs affect wood and steel beams in the same way, or are there differences? If you have a steel beam and wood beam that can carry equal loads; will the same hole drilled in the beams weaken them equally? Does screw-holes weaken a beam?
The steel beam is more accommodating to holes, since most of the material is in the top and bottom flange. With timber you are in danger of weakening the whole beam, as the whole of the section is used to resist bending and shear.
i would like build a room with steel but i do not know what size should i used and what space between columns . my space is 4X6 M and there Wall from 3 side . no wind there .
Hi Robin I have a 3 ply LVL 24' long x 5-1/4" thick x 18" deep specced for a job. Is there a easy way to convert this to steel? I have all the Member Information and Analysis Results for the wood beam. I have checked with my steel supplier and they don't do this, and I am not sure if I could find a Engineer to take time out to do this. If you could point me in the right direction that would be very helpful.
Hi. Any structural engineer would be able to carry out this calculation for you. Or contact us here forms.gle/ooxdhbUT6ku4jBkP9 Or you can take a look at this course if you would like to learn how to spec a steel beam yourself: geni.us/beamcalculations
Hi Robin. ending up with the equivalent of 4 250 x 100 timber beams, makes me wonder if actually the U Beam is way over spec. What are your thoughts on some structural requirements in residential building. I know this is a very vague, and broad question to be putting to you. but sometimes I get the feeling, 'is this size beam really needed'. I guess engineers are left having to calculate structural dimensions for the least common denominator. Thanks Robin.
Hi Jude. There is always the possibility in every industry that you get an inexperienced engineer who covers themselves by over engineering a beam. However this is rare. Bear in mind that beams need to be designed to stringent deflection limits, so even if a beam is more than strong enough to bear the load, it may still fail deflection criteria.
@@RobindeJongh Hi Robin. Excuse me, I missed your response. Thanks so much for making the effort to explain how there is more going on than I may imagine, which obviously, I greatly appreciate. I'm going to be demonstrating more ignorance here, but how much is 10kn/m. The reason I ask is that I am looking at installing a 4.8m beam myself, across an opening that will have the post from a gable roof ridge beam sitting right in the middle of it, that itself will be supporting a sheet metal roof, less than 40kg/m2, with a RLW of 3.2m. It scares me to think I'd be needing a timber beam anywhere near the size mentioned here. Though like you say, as steel is so much stronger (37 x stronger) than timber, they dont need to be anywhere the size of timber. So a UB would probably be the only way to go. It's a juggling act between size and proportion and aesthetics, and money. Thanks Robin. Gives me a lot to think about. P.S. I tried making one of your calculations on my computer keyboard the other day but I couldn't for the life of me figure out how to work the 'log' sign on the keyboard. thanks again Robin.
Hi very interesting video I’m currently discussing steel with my structural engineer as I believe he’s over calculating he wants 203x203 UC 71 grade 43 both at 6500mm to run under the purlins but it’s impossible to get them in a loft as the size and weight makes this very difficult
@@RobindeJongh Thank you the way he has the steals it’s just not possible to be installed I don’t know anyone else to ask had a look on TH-cam and came across your page I don’t know any structural engineers who I could ring which would make life a lot easier
@@Midnight-tornado86 Hi. As I said, if you ask your structural engineer to design the steels "fully restrained" then they should become far smaller, cheaper, and lighter.
Can you make a video on how to calculate the header needed for a 6 feet opening on a 4 story, very rectangular flat roof home ? lol where the ceilings are 8 feet high haha. 😜
How does bolting smaller steel beams together to make a larger beam affect the beam choice. Any guidance on doing this to achieve suitable loadings. Also what would the loadings per M2 be if it was just a floor so no roof supporting was required.
Why not engineered timber and why not taller and thinner timber, i know it would take more space but when you have that in mind and design a building with it in mind then its different
I need a beam for 3 meter span . So i would like to put a beam 15 cm x 25 cm ( 3 beams glued together , 5 cm x 25 cm ) . Is that going to be ok ? Upstairs is a concret and block floor. Tnx
🚀Get the timber tables used in the video: geni.us/timbercalculation
hi robin, could you use a flitch beam instead of a steel . my floor spans around 6 meters and can you use it as a sister as you can only buy 4.8 m timber thanks.
250 mm x 100 mm is only a 4x10. Which 2 2x12 boards glulam together exceeds whats needed. Which is around 50$ per 16 foot board here. And a quarter of the weight of steel. A timber frame don't need fire suppression here. A steel beam collapses under it's only weight in 15 minutes at 1400*F. The wood beams take over and hour. A steel beam here is around 100$ per foot. Meaning 2 steel beams is more than I spent on all the wood for 24x24 foot skillion cottage rising up 24 feet including roofing.
Why not use the proposed stud wall above the beam as a fabricated truss to span the 5 metres?
Please make more of these videos super helpful 🙏🙏
Is there a table somewhere than can help with determining what size steel beam(s) would be needed to replace a 16height x 3.5 inch width (a doubled 1.75) x 25ft long LVL beam? I am even open to having an additional steel support if necessary.
A very interesting video. Have you ever used a flitch beam in this sort of scenario?
Flitch beams are mostly obsolete after the advent of engineered lumber (LVL, LSL, PSL)
Cheers Robin, very informative as always!
Could you do a video on when you choose a UB over a lintel?
I'm used to seeing brickies using PCC, steel box and steel cavity lintels where I'd have thought a UB would have been required due to spans
That's a very good idea!
@@RobindeJongh Cheers at very least it would be interesting! I've seen what must have been a 4m cavity lintel installed before and that can't have been leaving much of a safety factor!
@@MJWhelan1 The lintel suppliers have a trick up their sleeve, which is that they increase the lintel depth and steel thickness the bigger the span, even though they call it the same lintel name.
@@RobindeJongh Completely appreciate that the depth and thickness have to change to accommodate the increase in length and load like all beams, guess I am just interested in if there is a point in the calcs/decision making process that a lintel is determined as more appropriate than a UB?
Would like to see the calcs using hardwood, tried to find tables to work it out but didnt have much luck not sure where to start looking
Hello
I looking to support 700kg
320cm long
Wich beam should I use
I dont have idea .
Thank You for help
Then you for clarification. Now I understand better the difference between steel and the timber 😊👍🏻
Hello Sr. I'm planning to build a patio cover that measures 7meters by 3.5 meters I would like to use an I beam 7meters go to put wood beams on it .would you please tell me what kind of measures I need on the I beam for this proyect.?
I may put 2 500 lbs. Thank you.
The timber beam section modulus of 4168 can be achieved using only TWO 250 x 100 beams, stacked vertically.
The extra height of the stacked beam is not a problem in this attic. However attaching the joist at 90 might be less convenient than onto the steel beam.
I believe you can achieve even better stiffness and load bearing capability with a more elaborate truss design, using an even lower volume of wood. Granted, it's much more work to build a wooden truss than to just slap a steel beam in place. Then again, a steel beam on an exterior wall always significantly reduces thermal insulation properties (i.e. enough to feel it in your wallet), compared to something using wood, unless you build up the insulation.
....just making the point that two beams stacked on their narrow sides improve the section modulus by 4 times. i.e. the square of the height/depth increase.
Hi Joe - correct, increasing the vertical height is most economical, though the beam would need to be very well restrained to stop it buckling.
I think one of the main limitations of timber is the deflection that occurs under live loading within permissible stress, sometimes to an extent that results in cracked plaster etc.
Wow. Nice practice.
hence the use of Glulam/LVL/Parallam etc.. :)
Hi John. Just a thought, I need a ridge beam for a project. I have many 200 x 50 timbers that were spare from another job. Instead of using 2 side by side and bolted could I use them on top of each other to make a 400 x 50 ? I would aim to mechanical fix and glue together but more importantly to clad both sides with 12mm plywood glued and screwed to prevent each timber moving independently. Not allowing for any strength the plywood gives where would this timber, 400 x 50 sit in your timber calculation table as they only go up to 250mm ? Thanks
Your beam would definitely be subject to bukling. But the real question is, what is your span and expected load?
Great video. thanks. Could you compare steel and concrete precast beams?
What about if you used the timber in a timber frame structure (similar to ladder horizontal ) then screwed and glued both sides , so you get the depth . This could be constructed on site and would be far easier to handle that a large steel girder ? ?
Where did the 1.5 factor for steel come from? Is that considering that all of the 10kn/m is a live load?
Hi. the 1.5 load factor is a combination of the usual 1.6 for imposed load and 1.4 for dead load.
Very informative,, thank you
Interesting thanks. I see a lot of discussion on whether to use timber or steel needles when propping walls above for steels to go underneath. Maybe use could compare the strength of those?
How did you picked C24 grade timber with 7.5n/mm2 over others? Thanks.
C24 and C16 are the commonly available grades in the UK. C24 is stronger, so I went with that.
How about with the steel sandwiched between timber.
One would think that would be a good way of increasing strength, steel plate laminated with bolts between 2 timbers
You want the higher tensile material farther away from the neutral axis. So two steel plates with wood in between could maybe be viable. The wood would act like the flange (or web) in an I beam. The wood would be under shear stress and the steel would be under compression on top and tension on the bottom. The wood and steel would have to be bonded together well somehow. It is no good otherwise.
Cheers Robin for a 5m span what size of c24 timber
Thank you Robin
Can you do a video soon on Units
I have always struggled with conversions like cm^4 to mm^2
And how to cross off units above and below the line ( if you know what I mean)
Thank you for sharing your knowledge and for the tables .
Kind Regards,
Peter
Hi Peter. Great suggestion! Units are probably the biggest thing engineers get tripped up on when doing hand calculations.
For a residential second floor joists how much can I span 2"x6" (with 1/8" web thickness) mild steel I beams at a 30 sq ft live load and also 40 sq ft live load? Thank you.
From memory steel is 20 times stronger than timber in bending. Worth knowing as a comparison. Deflection important also.
Why do you not factor the UDL on the timber beam calculation like you did with the steel?
By the way, fantastic video, thank you for showing all the steps. Very helpful!
Thanks - glad you liked it! Steel design to BS5950 is "limit state" philosophy, so you factor the loads. Timber design to BS5268 is "allowable stress" philosophy, which means the allowable stress for the material already has a factor of safety in it. Confused yet?!
@@RobindeJongh That is clear thank you. I am used to CSA codes and no not do much timber design (not since school anyways). Thanks for clarifying!
Would adding steel between the wooden beams, turning it into a flitch beam bring it up the same spec as the eye (I) beam.
Hi Anthony. Not quite, but it would be a big increase in strength and stiffness.
Thanks Robin. Why did you use 7.5 N/mm2 as the value for C24 timber? In Eurocode tables I see it is 24 N/mm2 for bending.
Using British Standards, we use allowable stress, which hsa factors of safety built in. Eurocode has changed this to limit state design, which uses a figure of ultimate stress.
Very informative thank you…. Have liked and subscribed 👍
Robin; can you explain the difference between steel and wood beams when it comes to nothcing, drilling holes etc? Does holes and cut-outs affect wood and steel beams in the same way, or are there differences? If you have a steel beam and wood beam that can carry equal loads; will the same hole drilled in the beams weaken them equally? Does screw-holes weaken a beam?
The steel beam is more accommodating to holes, since most of the material is in the top and bottom flange. With timber you are in danger of weakening the whole beam, as the whole of the section is used to resist bending and shear.
i would like build a room with steel but i do not know what size should i used and what space between columns . my space is 4X6 M and there Wall from 3 side . no wind there .
Your calculation is based on strength equivalency, however, we also need to assess the stiffness equivalence.
Hi Scott. Correct, stiffness (i.e. deflection) also needs to be calculated, and that would be the next step as I mentioned in the video.
@@RobindeJongh I’m looking forward to your next video.
Hi Robin
I have a 3 ply LVL 24' long x 5-1/4" thick x 18" deep specced for a job. Is there a easy way to convert this to steel?
I have all the Member Information and Analysis Results for the wood beam. I have checked with my steel supplier and they don't do this, and I am not sure if I could find a Engineer to take time out to do this. If you could point me in the right direction that would be very helpful.
Hi. Any structural engineer would be able to carry out this calculation for you. Or contact us here forms.gle/ooxdhbUT6ku4jBkP9 Or you can take a look at this course if you would like to learn how to spec a steel beam yourself: geni.us/beamcalculations
@@RobindeJongh Thank you
What about a flitch beam?
How does this compare with engineered timber, e.g glue laminated timber?
Hi Chris. Glulam is stronger than ordinary timber and also you can get a much deeper beam section size.
Hi Robin, 1.5 F.O.S is for live load is it not?
Hi. With British Standards steel design, the FOS for dead loads is 1.4 and live loads 1.6, so you can use a combined factor of 1.5 to simplify things.
@@RobindeJongh thank you
So how would you compare your steel beam to a glulam beam instead?
Hi Shane. Thanks for the suggestion - I'll add this to the list.
Hmm.. where did 275 come from?
I wish he reply!
Hi Robin. ending up with the equivalent of 4 250 x 100 timber beams, makes me wonder if actually the U Beam is way over spec. What are your thoughts on some structural requirements in residential building. I know this is a very vague, and broad question to be putting to you. but sometimes I get the feeling, 'is this size beam really needed'. I guess engineers are left having to calculate structural dimensions for the least common denominator. Thanks Robin.
Hi Jude. There is always the possibility in every industry that you get an inexperienced engineer who covers themselves by over engineering a beam. However this is rare. Bear in mind that beams need to be designed to stringent deflection limits, so even if a beam is more than strong enough to bear the load, it may still fail deflection criteria.
@@RobindeJongh Hi Robin. Excuse me, I missed your response. Thanks so much for making the effort to explain how there is more going on than I may imagine, which obviously, I greatly appreciate. I'm going to be demonstrating more ignorance here, but how much is 10kn/m. The reason I ask is that I am looking at installing a 4.8m beam myself, across an opening that will have the post from a gable roof ridge beam sitting right in the middle of it, that itself will be supporting a sheet metal roof, less than 40kg/m2, with a RLW of 3.2m. It scares me to think I'd be needing a timber beam anywhere near the size mentioned here. Though like you say, as steel is so much stronger (37 x stronger) than timber, they dont need to be anywhere the size of timber. So a UB would probably be the only way to go. It's a juggling act between size and proportion and aesthetics, and money. Thanks Robin. Gives me a lot to think about. P.S. I tried making one of your calculations on my computer keyboard the other day but I couldn't for the life of me figure out how to work the 'log' sign on the keyboard. thanks again Robin.
thank s another
HOW MUCHE DEFIANCE white between 5 meter I steel temperature to equate 5 meter wood temper ?
Friend from Baghdad. 27 inlay 2024
Thank you for his beneficial video =)
Thanks Noah 👍
Flitch ?
Good call, Douglas.
@@RobindeJongh Definitely needed for me. I am looking into a flitch solution instead of steel beams for a loft conversion.
Hi very interesting video I’m currently discussing steel with my structural engineer as I believe he’s over calculating he wants 203x203 UC 71 grade 43 both at 6500mm to run under the purlins but it’s impossible to get them in a loft as the size and weight makes this very difficult
Hi. I suggest asking your structural engineer if he would mind considering the beams to be "fully restrained" by connecting them to the floor joists.
@@RobindeJongh Thank you the way he has the steals it’s just not possible to be installed I don’t know anyone else to ask had a look on TH-cam and came across your page I don’t know any structural engineers who I could ring which would make life a lot easier
@@Midnight-tornado86 Hi. As I said, if you ask your structural engineer to design the steels "fully restrained" then they should become far smaller, cheaper, and lighter.
Can you make a video on how to calculate the header needed for a 6 feet opening on a 4 story, very rectangular flat roof home ? lol where the ceilings are 8 feet high haha.
😜
How does bolting smaller steel beams together to make a larger beam affect the beam choice. Any guidance on doing this to achieve suitable loadings. Also what would the loadings per M2 be if it was just a floor so no roof supporting was required.
Why not engineered timber and why not taller and thinner timber, i know it would take more space but when you have that in mind and design a building with it in mind then its different
Very good points. In the UK engineered timber is not always widely available, but it is getting better.
I need a beam for 3 meter span . So i would like to put a beam 15 cm x 25 cm ( 3 beams glued together , 5 cm x 25 cm ) . Is that going to be ok ? Upstairs is a concret and block floor. Tnx
Hi Lacy. You wouldn't want to support a concrete floor on a timber beam, in my view. Best to get a beam designed by a structural engineer.
Absolutely useless in fig newtons...