I agree in theory on your point about not putting vapor barrier on the inside wall in basement but if you do, you will fail building inspection in most provinces in Canada. It's building code to install it that way.
That's exactly right. To address older existing basements, check out this other video on the channel: th-cam.com/video/Lm9q8X2L47I/w-d-xo.htmlfeature=shared
In western Canada, it was code for many years to have vapor barrier between the concrete wall & framing, as well under the drywall. The building code changed in the late 90's-early 2000's, no more vapor barrier permitted between the concrete wall,.& the framing. It was discovered that moisture was building up in between that vapor barrier, & the concrete, mostly from frost build up during winter months. The moisture would remain almost indefinitely, and emit a mildew odor, usually at its worst in the early spring.
There was a lot wrong with the BC building codes previously... 'leaky condos' being one prime reason for change. Water is the enemy of wood... do whatever you can to eliminate its ingress from outside first. Then make sure whatever is inside can breathe its way out.
That's BS! You have obviously never worked in residential construction. By code, and going back to the 90's, you have been required to install an exterior felt between the foundation and the interior walls of the basement. After studding the walls, insulating etc., THAT is when you apply the vapour barrier!!!
Glad I saw this video before starting on my basement. I have a 2017 build home just outside Toronto, and was initially going to leave up the builders vapour barrier on the concrete wall that surrounds the Earth under the garage floor. But I’ll definitelyuse the rigid foam approach and then frame on top of that.
Great video - Amen! It took me 15+ years of home ownership before I learned this the hard way. Eventually figured out that no vapour barrier and rigid foam is the only way to go!
i have been in construction for 40 years. I have really never seen a good way to finish a basement other than drylocking the concrete and keeping it open. Radiant heat helps a lot though.
Problem with this is the foam board will get water logged. It doesn't matter what the manufacturers say. I've seen videos here on YT of XPS & EPS being pulled out of the ground from basements completely soaked. This negates any insulation benefits and is a very expensive waste.
Such an incredibly informative video. I had vapor barrier installed on painted concrete block basement walls about 5 years ago...along with an internal French drain. In less than 6 months, I could see the mold growth "everywhere" behind the barrier. The walls were already painted when I purchased the home and while the basement "felt" pretty dry, I was seeing signs of water infiltration. Fast forward to today, I now have foundation issues. The vapor barrier isn't the cause but if I had come across this video 5 years ago (along with other info I've recently uncovered), I would not have allowed the contractor to put the barrier on the walls. I have clay soil, a yard that grades toward the home and cast iron pipes that act as both a sewer line and storm drain. The pipes need to be replaced (in process now). Also, the side of my house is only 8 feet from my neighbor's driveway retaining wall - and the back of their yard slopes to the back corner of my home. A bit of a perfect storm. The information you share is invaluable.
If you buy a new home save money on the initial purchase by leaving your basement undeveloped this will give you a chance to see what state your foundation walls are in by the end of construction.. seen some pretty large cracks in the past that just get covered up . If you have walls that are not in the mechanical room covered up and the rest are bare I would tear that out to make sure the builder wasn't trying to hide something... Just a friendly tip..
We have a basement built using PWF - permanent wood foundation. Amongst other requirements was that there be granular drainage on the outside of the foundation walls, which continues on underneath the walls and the floor, then is tied into a sump pump. Our basement has never been anything but bone dry... it's probably the driest space in the house. I can't say I've ever truly understood why concrete foundation walls are allowed to just be backfilled with whatever soil came out rather than requiring drainage.
Here in Sweden we are primarily installing permeable variants of basement insulation and drainage systems, such as Isodrän. They have probably been dominating for the last 15 years. The insulation is installed on the outside without any membrane. With gravel and drainage tubes below the basement walls. The idea is that the basement walls dry out from the inside, which requires a heated space, and causes a high humidity during the first months. With too high water table some membrane might be needed on the outside of the insulation.
The vapor barrier is cut out at ground level height every third stud spacing to eliminate the moisture trap. It works well and I have been building homes since the earl 70s.
Can you explain a bit more please? If the vapor barrier has intentionally added holes, how does it block moisture at all? Why doesn't that defeat even adding one?
I didn't install one when I finished my basement. I just put up walls with fiberglass batts and drywall. Left space between the wall and foundation and a gap at the bottom of the wall that's covered with trim. No mold.
Thankyou for this info - well-presented and informative. You are building for the future, not just to look good. I was working with a colleague when the Building Inspector approved the basement VB being to the local West Coast Canada code. When the BI left, my buddy cut the VB with a huge X, top to bottom - because, as he posited, the moisture would be retained within the stud bays... "Gotta let the walls breathe". I adopted that, but I really should have seen something like this video first. Remember, the code is the minimum... always improve on it. This video explains the best ways. I see you advise EPS, but it has its hazards - off-gassing, and combustibility in particular
New Construction foundation concrete floor has visqueen (plastic sheeting) placed on floor before poring concrete and walls are of foundation have thick layer of more visqueen wrapped around outside walls sometimes repeating the steps. That is Building code (for decades) where I live also keeps moisture from entering past visqueen, Tar may not be enough.
Great info! I have the original blueprints for my 1960 built walk out basement house. I'll be doing a remodel in the next few years and suspect I'll reach out to you for the best way to go about insulating the remodel. I like the way you think. I live in Vancouver Washington and like that you are local
Forget spray foam. People have had to tear their house apart after getting it sprayed. The manufacturing process happens in your house. If the chemicals don't mix right, you will have a health hazard right in your house.
I did my basement years ago. I dug the exterior walls down, installed 2” blue styrofoam down to the footings then went another layer of 2’’ for 2’. Gave me 4” for the frost line. Then i did the interior basement walls with 1” blue top to bottom. Basement is dry and warm. Seems to be okay to this day, i believe its been 25 years and no issues!
As a European it's amazing to see how you heroically fight problems that you yourselves have created. Water bariers/insulation shall be done on the outside, yet I constantly see highly praised new constructions where the same errors are repeated over and over again. You pour concrete into the ground with soil on one side and basement on the other. Seriously ? And then heroically fight problems created by that "design". Frankly I dont know what to call it, some kind of mass -blindness ? Builders' conspiracy to make things bad by design so someone will have to go back and fix it forever ? Hard to say, but funny to watch nontheless. On that note I agree with your observations about this whole internal insulation thing - but this should be done exclusively only when there are no other options. Certainly not with new developments. Please, if you have the power, fix it! :)
I think you also need to do a video on exterior foundation insulation in this context….other than the issue of deterioration/bugs, it is another viable approach yes?
Absolutely, if you can protect the exterior insulation from bugs and moisture, it works great. The problem is that this can get complicated depending on what type of rigid insulation you're using. Rigid foams installed on the exterior of the foundation walls have to be treated like ICF foundations, with a fully adhered membrane bonded to the rigid foam, and even that can pose compatibility issues with the adhesives. Rockwool works but you need thick layers and a protection course. For durability reasons I very much prefer installing the insulation on the interior for below grade walls. You can also locate it interstitially, as in the case of a "sandwich" panel, and that works great as well since the insulation is protected.
@@ASIRIDesignswhy does it need to be glued to the concrete? The idea is to keep the entire concrete wall above the dew point. I don’t see how a gap matters. I’ve seen SM board with drainage channels onto the house.
Good question, I’m assuming many places have it as code. I’ve ripped out many basement walls in Winnipeg and found mold and rotten studs behind the poly. I think it has more to do with the quality of the foundation walls and damp proofing on the outside of the walls letting moisture in. Just my opinion on what I’ve seen in this area
Beautiful!! I was sceptical at first, but all that you detailed follows all that I know and makes Perfect logical/scientific sense. You have just upped my game. I'm in and subscribed! Thank you. Ps, just by default, I installed riding sheet foam on my basement walls, YAY!
I have been thinking this for years as the basement walls would have moisture and you had the pink insulation it would get wet and not be able to breath with the vapor barrier. I found this was the case when I purchased another home build in 1950 with a reno in the basement. I noticed drywall was soft so I knew it was getting wet even with the barrier. I have to tear it all out and do foam board first
Question. What about rigid foam exterior. Below grade. Applies over a proper waterproofing membrane applied directly to exterior concrete foundation. Foam is sealed onto exterior as well. Then the foundation is allowed to breath and dry out properly for a couple of years. Then, finish basement. No vapour barrier. I’m not an engineer. I’m asking a question. What is the best most effective method of having a finished basement.
@@FrankandaTrailer That works well, but only if you're able to keep the rigid insulation dry and away from ants and termites (easier said than done). Ants love to burrow into foam, especially damp or wet foam, and so from a durability standpoint my preference is to locate that insulation layer on the interior.
Spray foam will be like aspestos in the future , I won’t use any product in a house that is toxic , many products that will do the job that won’t slowly kill you . 🇨🇦👍
Im renovating our basement now, the wall framing and insulation is dry and no mold at all. And thats with a vapor barrier. The floor had vapor barrier on the concrete, then 5cm insulation. A lot of water there, so we're doing 10cm xps, then vapor barrier, then 5cm xps with concrete on top. That'll fix the floor issues. But should i put vapour barrier on the walls as well then since its worked fine in the existing walls for 40 years? We're putting up wooden panels again, since it's better than drywall in moist enviroments. Only difference is that we wont put up the black paper stuff behind the wood. just a 2cm air gap with a thick layer of asphalt stuff under the wood so its not in direct contact with the concrete.
Ironically, 15 years ago basement apartments were not permitted in most Canadian cities, but now they accomodate 100 000 newcomers. It seems hypocritical, but most municipalities encourage basement apartments, whereas they used to prohibit them.
Isn’t it time to move away from this antiquated building style. There are new scientific materials that can be poured in forms to build. They are lighter than concrete with superior water proofing & insulation.
This guy talks really fast. lol. Seems like some good info her if you can keep up. lol. Assuming these principles apply to dirt floor crawlspaces as well?
Wouldn't it make more sense to put the insulation outside so as to prevent moisture from penetrating the concrete. That way, the concrete would slowly lose moisture from inside if the basement is properly aired out.
Used pink panther foam against the concrete block and then used a pvc bottom plate for the 2x4 walls. It has worked out really well we also keep a eye on moisture content of our basement air and run a dehumidifier in the moist months have had many comfortable years in the basement rooms. Lived in the house for a few years monitoring the Block walls We live on a hill above town and all the landscape around the house pitches away nicely and I added Gutters for extra water control. Made sure to have no major leaks before attempting framing and drywall. Good luck to any one upgrading living space.
I am interested in how the engineering and insulation and ventilation profiles are altered in the case where an interior drainage system is install IE like Delta MS or AG foundation drainage membrane and interior weeper or "french drain". If a Radon fan is installed in the sump it will cause depressurization and ventilation of not only the slab but that area behind the drainage mat. It also makes sheet styrofoam more difficult to install. In this case if no styrofoam was installed would a vapour barrier be reccomended ? Interior drainage systems are gaining huge popularity for cost reasons and being sold as "waterproofing" , which it is not, and being done prior to basement finishing. The ADU basement apartment builds are booming in this manner.
We sometimes hang our 2x4 top plates staple plastic to the face of that then add another top plate to create a plastic drape behind the wall usually 1 to 2 inches away from the concrete foundation, then pull the plastic under our bottom plate before fastening to the slab , and stick frame and toe nail our studs . ( Chicago climate )
I did this exact same thing on my basment foundation, but also added plastic between the framing/unfaced insulation and sheetrock, is that OK to do as well?
There is supposed to be an expansion joint between the basement cement floor and the foundation, with a "Big - O" drain, underneath the floor and then an exterior felt, such as house wrap or tar paper between the studs and the foundation so that any moisture runs down between the foundation and the felt to get it to keep the insulation dry and seep the moisture into the Big - O. You should NOT be trying to give information, kiddo!!!
The reason for the felt vs Styrofoam is because with Styrofoam the foundation cant breath anymore than if you put Poly over it. That is why you get a exterior breathable felt that will help the foundation to breath, without getting the insulation wet. Get a job in construction before you call yourself an intelligent advisor because you have it ALL wrong and hopefully, someone sues you!!!
I do have a vapor barrier in mine. But its applied right on the concrete wall, stops at about 2 ft from the floor. The studs are applied on the vapor barrier, which means the plastic film is squeezed between the studs and the concrete wall. There's also isolating foam panels which go from the ceiling to about 2ft from the floor. Dunno if that's desirable or not. No mold though, like at all, unless its deeply hidden behind the drywall... sure hope not!
What do you recommend for a wood foundation with polyethylene which is not a perfect air barrier (overlapped and stapled instead of taped, gaps near receptacles, etc)?
Then you have all the problems with rigid insulation a) releasing toxic gas into the house interior and releasing toxic gases when it burns in a house fire. There is no free lunch and the authors of this video should not gloss over that fact.
Why would you think that a 6 mil plastic vapor barrier would stop fumes from any burning insulation (even stipulating that the insulation wasn’t flame retardant)???
What if you built two independent sets of concrete foundation walls, on separate footings, and filled the space between them with gravel to allow water to be removed by French drains at the bottom? (You could cover the space in between to deflect surface water.) You could go even farther by installing standard sump pumps between the two walls to mitigate rising groundwater. More than one if you like, why not. Certainly, the interior of the two walls would be less wet, and its temperature less impacted by the soil temperature, than a single wall assembly. How would you rate this scheme, and if someone was serious about doing it, how might you built it? Sometimes entertaining a theoretical idea, even if impractical, can provide ideas. Maybe there’s a video on things like this waiting to be done?
Thinking back (24+ years ago), my builder used metal studs with pink insulation and vapour barrier from floor to ceiling in the whole basement. 7 years later, I finished the basement ( added some interior walls and electrical around the perimeter, so i had to cut the barrier to feed some electrical around the basement walls. I didn't notice any mold. This video makes though. Should I bust open a section to check, or just leave well enough alone?
Vapour barriers in basements don't always cause problems. My parents' house had no problems after 50 years when we recently renovated the basement. But it also has extremely well-draining sandy soil and a concrete block foundation wall with open cavities. It depends on the conditions.
Couldnt you cast the basement wall with waterproof concrete mix (ie: materproof admixture)? that should address half of the problem with moisutre coming in from the outside.
You can, but here's the thing... All concrete cracks. Cracks are pathways for water to enter via hydrostatic pressure. So a drained system is the only way to prevent bulk water from getting inside. As for the other capillary forces and interior vapor drive/air leakage, they need to be addressed accordingly.
at 2:56 you talk about 'the right ratio' between the ridgid foam applied to the concrete wall vs the fiberous batts installed interior of that foam. I've read up on the ratios required for main floor walls, is this the similar ratio you are basis this off of, or is there a similar table where this can be looked up by climate zone? Thanks
The vapour barrier should be located where it will always be at a temperature above the dew point. Determine the worst case dew point for your climate for all seasons. The foam thickness to permeable insulation thickness ratio needs to be greater than the ratio of the dew point within the indoor - outdoor temperature delta. Note that the outdoor temperature below grade is different than above.
Ive been questioning this for many years. Concrete walls could sweat and therefore a plastic barrier would not let the insulated wall breathe behind the drywall
How do you feel about insulated concrete forms? Based off the information in this video of having a couple inches of Styrofoam to prevent moisture/mold issues and still allowing the wall system to dry this seems like an ideal method of constructing not only basements but above ground as well.
ICFs are a good system but they aren't a panacea. As I was telling another person in the comments, ICFs absolutely must be protected from water infiltration and insect damage with a fully adhered membrane, but it gets complicated because the membrane and the adhesives have to be compatible with the EPS foam, otherwise things like solvent based adhesives dissolve the foam. Any system can be made to work as long as the the foundation is well drained and the layers are in the right location. That's the key.
Can you comment on using Zypex concrete waterproofing. I understand it promotes crystal growth into the concrete, sealing it, the product reacts to water infiltration.
Xypex is a liquid water crack sealer. It does not block transmission of air and/or water vapor. It would make no different for vapor moving through the concrete toward your vapor barrier.
I recommend considering hemp fiber insulation alongside mineral wool…(one brand rockwool), with similar qualities/benefits. I am planning to build a hempcrete home and will use the hemp fibre bats in the ceiling and crawlspace. :)
hemp is organic and organic means it can turn into food for mold. All you need is some vapor condensation inside the hemp and you've just built a really expensive mold farm by accident. I don't think it sounds like the right application for hemp fiber insulation.
Wouldn't it be wise to leave an air gap between the rigid foam and the concrete foundation, and a dehumidifer that runs year round? This will wick moisture out from the walls... I did this and have a heat pump water heater that pulls heat and moisture from the basement. Its a new system so time will tell but I can say the basement is minty cold in summer and seems dry down there. Planning to blueskin the exterior next summer...
@@brendanoneil3489i can tell when the heat pump has been running. It seems to oscillate between mild dampness and very dry. I have not had a winter down there yet since the heat pump install, but the walls are R24, will be R36 once I blueskin and insulate the rest of the exterior. Just hoping frost heave doesn't crack anything open before I manage to finish the job. Last winter was mild, but the furnace system was set up so the basement was warmer than the upstairs with furnace on. Heat pump should balance that. Still figuring it out
Best thing home owners can do is to divert rainwater from gutters 10 feet away from foundations...the further the better and maintain good air flow in any basement by controlling temp in your basement...
There's technique for insulating basements with house wrap on the concrete block side first then studs, batt insulation and vapour barrier. What are you thoughts on this method?
Believe it or not, even "dry" soils are somewhat damp! You almost never have bone-dry soils except in extreme climates. Also consider that there is substantially less volume of air in soils, so the small amount of air that is inbetween the tiny gaps of soil particles aren't able to store much moisture in the first place.
@@ASIRIDesigns Ok I just stuck a hygrometer into a hole in the bottom of my foundation... I'm in a dry climate and I have no drainage issues, it's apparently bone dry crushed rock down there yet 98% humidity... Hah! The basement walls are insulated and barriered in the way you discourage. Unfortunately they are fully finished too... So I can't easily get the hygrometer into the walls.
Put the framing a half inch or so away from the concrete walls. Put fiberglass insulation in, with paper-backing already on. Then stapled clear, plastic vapor-barrier to the framed walls - but only to the below grade height (of the outside dirt). 30 years & counting with zero problems.
*A Design Guide To Dry & Comfortable Basements eBook* : asiri-designs.com/shop/ols/products/basement-design-guide
I agree in theory on your point about not putting vapor barrier on the inside wall in basement but if you do, you will fail building inspection in most provinces in Canada. It's building code to install it that way.
i assume this is for new builds with appropriate exterior water management and not for 84 year old basements
That's exactly right. To address older existing basements, check out this other video on the channel: th-cam.com/video/Lm9q8X2L47I/w-d-xo.htmlfeature=shared
Yes
In western Canada, it was code for many years to have vapor barrier between the concrete wall & framing, as well under the drywall.
The building code changed in the late 90's-early 2000's, no more vapor barrier permitted between the concrete wall,.& the framing.
It was discovered that moisture was building up in between that vapor barrier, & the concrete, mostly from frost build up during winter months.
The moisture would remain almost indefinitely, and emit a mildew odor, usually at its worst in the early spring.
There was a lot wrong with the BC building codes previously... 'leaky condos' being one prime reason for change. Water is the enemy of wood... do whatever you can to eliminate its ingress from outside first. Then make sure whatever is inside can breathe its way out.
My home was built in 2003 and has a vapour barriers on external walls. Over insulation and studs
@@Googaliemoogaliein the basement?
Whew. Glad someone figured it out. It’s pretty obvious if one has ever seen plastic sheets
That's BS! You have obviously never worked in residential construction. By code, and going back to the 90's, you have been required to install an exterior felt between the foundation and the interior walls of the basement. After studding the walls, insulating etc., THAT is when you apply the vapour barrier!!!
Glad I saw this video before starting on my basement. I have a 2017 build home just outside Toronto, and was initially going to leave up the builders vapour barrier on the concrete wall that surrounds the Earth under the garage floor. But I’ll definitelyuse the rigid foam approach and then frame on top of that.
Probably the most underrated building engineering channel.
Don't worry, the channel is gaining a lot of traction as it should :) cheers!
Great video - Amen! It took me 15+ years of home ownership before I learned this the hard way. Eventually figured out that no vapour barrier and rigid foam is the only way to go!
There is a reason why they're used in some aspects in concrete forming structures.
@@timothychung4811 oooh but it must be secret because you don't explain it ?
i have been in construction for 40 years. I have really never seen a good way to finish a basement other than drylocking the concrete and keeping it open. Radiant heat helps a lot though.
Insulation on the exterior wall. Simple and super effective ! The saturation point (dew point) won't be in the basement, but outside.
2-4” of SM board on the outside of the concrete. Stops all the problems. Insulation needs to be on the outside of the building.
Problem with this is the foam board will get water logged. It doesn't matter what the manufacturers say. I've seen videos here on YT of XPS & EPS being pulled out of the ground from basements completely soaked. This negates any insulation benefits and is a very expensive waste.
@@3rett115it’s also only realistic on a brand new build and impossible for someone finishing an existing basement anyway
Such an incredibly informative video. I had vapor barrier installed on painted concrete block basement walls about 5 years ago...along with an internal French drain. In less than 6 months, I could see the mold growth "everywhere" behind the barrier. The walls were already painted when I purchased the home and while the basement "felt" pretty dry, I was seeing signs of water infiltration. Fast forward to today, I now have foundation issues. The vapor barrier isn't the cause but if I had come across this video 5 years ago (along with other info I've recently uncovered), I would not have allowed the contractor to put the barrier on the walls. I have clay soil, a yard that grades toward the home and cast iron pipes that act as both a sewer line and storm drain. The pipes need to be replaced (in process now). Also, the side of my house is only 8 feet from my neighbor's driveway retaining wall - and the back of their yard slopes to the back corner of my home. A bit of a perfect storm. The information you share is invaluable.
If you buy a new home save money on the initial purchase by leaving your basement undeveloped this will give you a chance to see what state your foundation walls are in by the end of construction.. seen some pretty large cracks in the past that just get covered up . If you have walls that are not in the mechanical room covered up and the rest are bare I would tear that out to make sure the builder wasn't trying to hide something... Just a friendly tip..
We have a basement built using PWF - permanent wood foundation. Amongst other requirements was that there be granular drainage on the outside of the foundation walls, which continues on underneath the walls and the floor, then is tied into a sump pump. Our basement has never been anything but bone dry... it's probably the driest space in the house. I can't say I've ever truly understood why concrete foundation walls are allowed to just be backfilled with whatever soil came out rather than requiring drainage.
Matt Risinger recently put out a video on wood foundations. It only scraped the surface but interesting.
Here in Sweden we are primarily installing permeable variants of basement insulation and drainage systems, such as Isodrän. They have probably been dominating for the last 15 years. The insulation is installed on the outside without any membrane. With gravel and drainage tubes below the basement walls. The idea is that the basement walls dry out from the inside, which requires a heated space, and causes a high humidity during the first months. With too high water table some membrane might be needed on the outside of the insulation.
They build a water proof concrete bottomed box.
The vapor barrier is cut out at ground level height every third stud spacing to eliminate the moisture trap.
It works well and I have been building homes since the earl 70s.
Can you explain a bit more please?
If the vapor barrier has intentionally added holes, how does it block moisture at all? Why doesn't that defeat even adding one?
I didn't install one when I finished my basement. I just put up walls with fiberglass batts and drywall. Left space between the wall and foundation and a gap at the bottom of the wall that's covered with trim. No mold.
Thankyou for this info - well-presented and informative. You are building for the future, not just to look good. I was working with a colleague when the Building Inspector approved the basement VB being to the local West Coast Canada code. When the BI left, my buddy cut the VB with a huge X, top to bottom - because, as he posited, the moisture would be retained within the stud bays... "Gotta let the walls breathe". I adopted that, but I really should have seen something like this video first. Remember, the code is the minimum... always improve on it. This video explains the best ways.
I see you advise EPS, but it has its hazards - off-gassing, and combustibility in particular
New Construction foundation concrete floor has visqueen (plastic sheeting) placed on floor before poring concrete and walls are of foundation have thick layer of more visqueen wrapped around outside walls sometimes repeating the steps.
That is Building code (for decades) where I live also keeps moisture from entering past visqueen, Tar may not be enough.
Would the intello membrane work for the basement concrete slab as well?
Great info! I have the original blueprints for my 1960 built walk out basement house. I'll be doing a remodel in the next few years and suspect I'll reach out to you for the best way to go about insulating the remodel. I like the way you think. I live in Vancouver Washington and like that you are local
Forget spray foam. People have had to tear their house apart after getting it sprayed. The manufacturing process happens in your house. If the chemicals don't mix right, you will have a health hazard right in your house.
I did my basement years ago. I dug the exterior walls down, installed 2” blue styrofoam down to the footings then went another layer of 2’’ for 2’. Gave me 4” for the frost line. Then i did the interior basement walls with 1” blue top to bottom. Basement is dry and warm. Seems to be okay to this day, i believe its been 25 years and no issues!
As a European it's amazing to see how you heroically fight problems that you yourselves have created. Water bariers/insulation shall be done on the outside, yet I constantly see highly praised new constructions where the same errors are repeated over and over again. You pour concrete into the ground with soil on one side and basement on the other. Seriously ? And then heroically fight problems created by that "design". Frankly I dont know what to call it, some kind of mass -blindness ? Builders' conspiracy to make things bad by design so someone will have to go back and fix it forever ? Hard to say, but funny to watch nontheless.
On that note I agree with your observations about this whole internal insulation thing - but this should be done exclusively only when there are no other options. Certainly not with new developments. Please, if you have the power, fix it! :)
I think you also need to do a video on exterior foundation insulation in this context….other than the issue of deterioration/bugs, it is another viable approach yes?
Absolutely, if you can protect the exterior insulation from bugs and moisture, it works great. The problem is that this can get complicated depending on what type of rigid insulation you're using. Rigid foams installed on the exterior of the foundation walls have to be treated like ICF foundations, with a fully adhered membrane bonded to the rigid foam, and even that can pose compatibility issues with the adhesives. Rockwool works but you need thick layers and a protection course. For durability reasons I very much prefer installing the insulation on the interior for below grade walls. You can also locate it interstitially, as in the case of a "sandwich" panel, and that works great as well since the insulation is protected.
@@ASIRIDesignswhy does it need to be glued to the concrete? The idea is to keep the entire concrete wall above the dew point. I don’t see how a gap matters. I’ve seen SM board with drainage channels onto the house.
Very informative. Was always unsure about building basement walls the best way
Great uploads. Love the raw data.
Thanks so much, glad the videos have been helpful!
Why does are building code here in Manitoba,Canada require it then???
Good question, I’m assuming many places have it as code. I’ve ripped out many basement walls in Winnipeg and found mold and rotten studs behind the poly. I think it has more to do with the quality of the foundation walls and damp proofing on the outside of the walls letting moisture in. Just my opinion on what I’ve seen in this area
This is why ICF works so well in the basement. Concrete is insulated and no further vapour barrier.
Beautiful!! I was sceptical at first, but all that you detailed follows all that I know and makes Perfect logical/scientific sense.
You have just upped my game.
I'm in and subscribed! Thank you.
Ps, just by default, I installed riding sheet foam on my basement walls, YAY!
Glad it was helpful!
Even better move is put Rigid foam board on the OUTSIDE basement walls ❤ all the way down to the frost line.
I have been thinking this for years as the basement walls would have moisture and you had the pink insulation it would get wet and not be able to breath with the vapor barrier. I found this was the case when I purchased another home build in 1950 with a reno in the basement. I noticed drywall was soft so I knew it was getting wet even with the barrier. I have to tear it all out and do foam board first
Vapour barriers are designed to breath. This is why they are not called vapour proof, nor an air barrier.
Question.
What about rigid foam exterior. Below grade. Applies over a proper waterproofing membrane applied directly to exterior concrete foundation. Foam is sealed onto exterior as well. Then the foundation is allowed to breath and dry out properly for a couple of years. Then, finish basement. No vapour barrier. I’m not an engineer. I’m asking a question. What is the best most effective method of having a finished basement.
@@FrankandaTrailer That works well, but only if you're able to keep the rigid insulation dry and away from ants and termites (easier said than done). Ants love to burrow into foam, especially damp or wet foam, and so from a durability standpoint my preference is to locate that insulation layer on the interior.
@@ASIRIDesignsyou can put the insulation on the inside if that’s where you want the bugs…
Spray foam will be like aspestos in the future , I won’t use any product in a house that is toxic , many products that will do the job that won’t slowly kill you . 🇨🇦👍
How about insulating it from the exterior side? Wouldn't that be simpler if it were a new build?
so if you are building an ICF basement should you tape seems in foam blocks
Avoid basements and crawl spaces of you can...
Do you design residential buildings, or have a catalog I could look at purchasing plans from?
Excellent explanation thank you!
Im renovating our basement now, the wall framing and insulation is dry and no mold at all. And thats with a vapor barrier.
The floor had vapor barrier on the concrete, then 5cm insulation. A lot of water there, so we're doing 10cm xps, then vapor barrier, then 5cm xps with concrete on top. That'll fix the floor issues.
But should i put vapour barrier on the walls as well then since its worked fine in the existing walls for 40 years? We're putting up wooden panels again, since it's better than drywall in moist enviroments. Only difference is that we wont put up the black paper stuff behind the wood. just a 2cm air gap with a thick layer of asphalt stuff under the wood so its not in direct contact with the concrete.
👍🏻👍🏻 thank you, very good info!
Ironically, 15 years ago basement apartments were not permitted in most Canadian cities, but now they accomodate 100 000 newcomers. It seems hypocritical, but most municipalities encourage basement apartments, whereas they used to prohibit them.
Isn’t it time to move away from this antiquated building style. There are new scientific materials that can be poured in forms to build. They are lighter than concrete with superior water proofing & insulation.
This guy talks really fast. lol. Seems like some good info her if you can keep up. lol. Assuming these principles apply to dirt floor crawlspaces as well?
Wouldn't it make more sense to put the insulation outside so as to prevent moisture from penetrating the concrete. That way, the concrete would slowly lose moisture from inside if the basement is properly aired out.
I’ve been running a dehumidifier in my basement for about 10 years now. Huge huge huge difference.
So complicated! Put 4” of SM board outside against the dirt and concrete. Done.
Thanks Sharif!
Or use ICF foundations and you do not need to worry about any of this. Also cheaper.
Used pink panther foam against the concrete block and then used a pvc bottom plate for the 2x4 walls. It has worked out really well we also keep a eye on moisture content of our basement air and run a dehumidifier in the moist months have had many comfortable years in the basement rooms. Lived in the house for a few years monitoring the Block walls We live on a hill above town and all the landscape around the house pitches away nicely and I added Gutters for extra water control. Made sure to have no major leaks before attempting framing and drywall. Good luck to any one upgrading living space.
I am interested in how the engineering and insulation and ventilation profiles are altered in the case where an interior drainage system is install IE like Delta MS or AG foundation drainage membrane and interior weeper or "french drain". If a Radon fan is installed in the sump it will cause depressurization and ventilation of not only the slab but that area behind the drainage mat. It also makes sheet styrofoam more difficult to install. In this case if no styrofoam was installed would a vapour barrier be reccomended ? Interior drainage systems are gaining huge popularity for cost reasons and being sold as "waterproofing" , which it is not, and being done prior to basement finishing. The ADU basement apartment builds are booming in this manner.
We sometimes hang our 2x4 top plates staple plastic to the face of that then add another top plate to create a plastic drape behind the wall usually 1 to 2 inches away from the concrete foundation, then pull the plastic under our bottom plate before fastening to the slab , and stick frame and toe nail our studs . ( Chicago climate )
I did this exact same thing on my basment foundation, but also added plastic between the framing/unfaced insulation and sheetrock, is that OK to do as well?
Argue that with the inspector! I did not want to be he wasn’t going to give in!
I dont think I have any type of vapour barrier on my basement walls. Doesnt seem to have been a problem yet. house built in 60's.
There is supposed to be an expansion joint between the basement cement floor and the foundation, with a "Big - O" drain, underneath the floor and then an exterior felt, such as house wrap or tar paper between the studs and the foundation so that any moisture runs down between the foundation and the felt to get it to keep the insulation dry and seep the moisture into the Big - O. You should NOT be trying to give information, kiddo!!!
The reason for the felt vs Styrofoam is because with Styrofoam the foundation cant breath anymore than if you put Poly over it. That is why you get a exterior breathable felt that will help the foundation to breath, without getting the insulation wet. Get a job in construction before you call yourself an intelligent advisor because you have it ALL wrong and hopefully, someone sues you!!!
Just buy a really good dehumidifier. Duh.
I do have a vapor barrier in mine. But its applied right on the concrete wall, stops at about 2 ft from the floor. The studs are applied on the vapor barrier, which means the plastic film is squeezed between the studs and the concrete wall. There's also isolating foam panels which go from the ceiling to about 2ft from the floor. Dunno if that's desirable or not. No mold though, like at all, unless its deeply hidden behind the drywall... sure hope not!
Please note that if the resin used on mineral wool is organic, mould will proliferate on that resin, conditions permitting.
What do you recommend for a wood foundation with polyethylene which is not a perfect air barrier (overlapped and stapled instead of taped, gaps near receptacles, etc)?
I don’t do building or anything connected, cool vid but like why did i even watch it XD
Then you have all the problems with rigid insulation a) releasing toxic gas into the house interior and releasing toxic gases when it burns in a house fire. There is no free lunch and the authors of this video should not gloss over that fact.
Why would you think that a 6 mil plastic vapor barrier would stop fumes from any burning insulation (even stipulating that the insulation wasn’t flame retardant)???
Inspector in my area makes us valor barrier even with the foam board behind the framing
Don't you also need to have an air barrier around the joists when you use rigid foam?
my unfinished old basement was leaky damp dried out quickly
Vapor barrier, is just that. Not going to help with moisture.
Instead of a wall how about curtains? Deaden sounds, washable, and simple to inspect for leaks.
What if you built two independent sets of concrete foundation walls, on separate footings, and filled the space between them with gravel to allow water to be removed by French drains at the bottom? (You could cover the space in between to deflect surface water.) You could go even farther by installing standard sump pumps between the two walls to mitigate rising groundwater. More than one if you like, why not. Certainly, the interior of the two walls would be less wet, and its temperature less impacted by the soil temperature, than a single wall assembly. How would you rate this scheme, and if someone was serious about doing it, how might you built it? Sometimes entertaining a theoretical idea, even if impractical, can provide ideas. Maybe there’s a video on things like this waiting to be done?
Buildings are built to a price point. That's additional labor and cost
Thinking back (24+ years ago), my builder used metal studs with pink insulation and vapour barrier from floor to ceiling in the whole basement. 7 years later, I finished the basement ( added some interior walls and electrical around the perimeter, so i had to cut the barrier to feed some electrical around the basement walls. I didn't notice any mold. This video makes though. Should I bust open a section to check, or just leave well enough alone?
Vapour barriers in basements don't always cause problems. My parents' house had no problems after 50 years when we recently renovated the basement. But it also has extremely well-draining sandy soil and a concrete block foundation wall with open cavities. It depends on the conditions.
buy dehumidifier and run it nonstop
Love this channel
Couldnt you cast the basement wall with waterproof concrete mix (ie: materproof admixture)? that should address half of the problem with moisutre coming in from the outside.
You can, but here's the thing... All concrete cracks. Cracks are pathways for water to enter via hydrostatic pressure. So a drained system is the only way to prevent bulk water from getting inside. As for the other capillary forces and interior vapor drive/air leakage, they need to be addressed accordingly.
Learn from Norway. No vapour barrier if more then a half of walls are UNDERGROUND. Insulate from outside with the XPS.
at 2:56 you talk about 'the right ratio' between the ridgid foam applied to the concrete wall vs the fiberous batts installed interior of that foam. I've read up on the ratios required for main floor walls, is this the similar ratio you are basis this off of, or is there a similar table where this can be looked up by climate zone? Thanks
The vapour barrier should be located where it will always be at a temperature above the dew point. Determine the worst case dew point for your climate for all seasons. The foam thickness to permeable insulation thickness ratio needs to be greater than the ratio of the dew point within the indoor - outdoor temperature delta. Note that the outdoor temperature below grade is different than above.
Added advantage to Mineral wool is that mice hate it
Ive been questioning this for many years. Concrete walls could sweat and therefore a plastic barrier would not let the insulated wall breathe behind the drywall
If you house is probably vented this is not an issue because the inside of the home can breath and moisture won’t be an issue.
Even more better IMO would be to install Pordrän or Isodrän on the outside basement wall!
How do you feel about insulated concrete forms? Based off the information in this video of having a couple inches of Styrofoam to prevent moisture/mold issues and still allowing the wall system to dry this seems like an ideal method of constructing not only basements but above ground as well.
ICFs are a good system but they aren't a panacea. As I was telling another person in the comments, ICFs absolutely must be protected from water infiltration and insect damage with a fully adhered membrane, but it gets complicated because the membrane and the adhesives have to be compatible with the EPS foam, otherwise things like solvent based adhesives dissolve the foam. Any system can be made to work as long as the the foundation is well drained and the layers are in the right location. That's the key.
The vapor barrier needs to go against the concrete. NOT BEHIND THE DRYWALL.
Absolutely wrong. It needs to be installed on the warm side of the wall this is the only thing that matters. Spray foam and steel studs are the best
Can you comment on using Zypex concrete waterproofing. I understand it promotes crystal growth into the concrete, sealing it, the product reacts to water infiltration.
Xypex is a liquid water crack sealer. It does not block transmission of air and/or water vapor. It would make no different for vapor moving through the concrete toward your vapor barrier.
I recommend considering hemp fiber insulation alongside mineral wool…(one brand rockwool), with similar qualities/benefits. I am planning to build a hempcrete home and will use the hemp fibre bats in the ceiling and crawlspace. :)
hemp is organic and organic means it can turn into food for mold. All you need is some vapor condensation inside the hemp and you've just built a really expensive mold farm by accident. I don't think it sounds like the right application for hemp fiber insulation.
Wouldn't it be wise to leave an air gap between the rigid foam and the concrete foundation, and a dehumidifer that runs year round? This will wick moisture out from the walls... I did this and have a heat pump water heater that pulls heat and moisture from the basement. Its a new system so time will tell but I can say the basement is minty cold in summer and seems dry down there. Planning to blueskin the exterior next summer...
also eliminates damp and cold bridging?
@@brendanoneil3489i can tell when the heat pump has been running. It seems to oscillate between mild dampness and very dry. I have not had a winter down there yet since the heat pump install, but the walls are R24, will be R36 once I blueskin and insulate the rest of the exterior. Just hoping frost heave doesn't crack anything open before I manage to finish the job. Last winter was mild, but the furnace system was set up so the basement was warmer than the upstairs with furnace on. Heat pump should balance that. Still figuring it out
Or, do all foundations with icf
Best thing home owners can do is to divert rainwater from gutters 10 feet away from foundations...the further the better and maintain good air flow in any basement by controlling temp in your basement...
This is quickly becoming ym favorite channel for building science. I hope you keep on keeping on. I like being an educated GC.
That’s what I did, all of it
If its in the building code you have to install it to pass the building permit inspections. So whats your answer to that?
Rip it off after the inspector pass lol
You can use a smart vapor retarder instead of polyethylene to allow for drying if conditions get wet. It's allowed by code.
Great video, well made.
ICF is king
Love all the graphics and clear information
what about off gassing?
Cool
Excellent explanation
There's technique for insulating basements with house wrap on the concrete block side first then studs, batt insulation and vapour barrier. What are you thoughts on this method?
It's the same problem.
@ASIRIDesigns disagree, it's not a problem on a properly poured and damproofed foundation wall
@blehssed how about a block wall built in the 1970's. It's probably not damproofed properly.
Why is soil at 100% humidity? Sounds like drainage issues.
Believe it or not, even "dry" soils are somewhat damp! You almost never have bone-dry soils except in extreme climates. Also consider that there is substantially less volume of air in soils, so the small amount of air that is inbetween the tiny gaps of soil particles aren't able to store much moisture in the first place.
@@ASIRIDesigns Interesting, yes reading around I see that even very slightly damp soil can have quite high humidity like 90+%.
@@ASIRIDesigns Ok I just stuck a hygrometer into a hole in the bottom of my foundation... I'm in a dry climate and I have no drainage issues, it's apparently bone dry crushed rock down there yet 98% humidity... Hah!
The basement walls are insulated and barriered in the way you discourage. Unfortunately they are fully finished too... So I can't easily get the hygrometer into the walls.
Mold food, yum
Thanks for sharing!
HRV!!!!!
Wo, wo. That one picture shows the back side of a shower/ tub situation. That's always a no no.
Did you say rigid foam IS a class II vapor retarder or rigid foam WITH a class II vapor retarder? 2:35.
Unfaced rigid foam itself IS a Class II vapor retarder
Put the framing a half inch or so away from the concrete walls. Put fiberglass insulation in, with paper-backing already on. Then stapled clear, plastic vapor-barrier to the framed walls - but only to the below grade height (of the outside dirt). 30 years & counting with zero problems.
Wouldn’t that create a tone of air and moisture penetration?
@@robertt9342 In the summer, we have a little de-humidifier on, like we did even before finishing the basement. No problems here, knocking on wood!
ridgid foam
The proper approach is to seal the outside of the basement not the inside.
If your foundation was built with ICFs you won't have this problem. I am surprised that ICFs are not more commonly used for foundations.