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!!!
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..
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.
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.
You may want to look up waterproofing foundations contractors. These details work even with PWF. They excavate foundation outside and apply a barrier, install weeping tile, and or regrade. PWF: = permanent wood foundations> they are required to have these details done rightby code. Concrete is more forgiving. I imagine your foundation isn't damaged structurally d, but you have water leaking in.
@@mrgregweber Indeed. I just had all the pipes under the concrete slab re-done. Sewer and storm drain now redirected to PVC pipes rather than aged cast iron. Internal french drain has been redone. All sloping towards drains that exit the house. Removed sump pumps which were not working well. Next step in the process is that I will be having the exterior of the home waterproofed - following ASIRI (and structural engineer) guidance of membrane, dimple board, insulation board, gravel, and exterior drain as well. Have to wait until spring for the landscape regrade, but that will be the final piece. The foundation continued to settle while the plumbers were excavating internally and installing pipe through the foundation walls. My guess is that there was sufficient presssure built up over time with failed pipes leaving excess water at the foundation, etc. And it released with excavation. Footer is concrete; foundation walls are concrete block. There are cracks in the block and mortar joint cracks on the exterior...and some cracked bricks. I was onsite for all of the interior work. I could see water coming in through prior installed weep holes. And during heavy rains, a bit too much water came through the weep holes in my opinion - but my experience in this area is quite limited. Structural engineer indentified that the exterior waterproofing will strongly mitigate the internal seepage (hopefully bringing it to a "drip") and that the internal drain will act as an emergency backup should anything get past the external waterproofing.
@@julibark713 It sounds like you are talking to local professionals. Accredited local professionals are always needed as areas differ and accordingly have different code. Some areas even have code that needs updating so you really need to rely on good pros. What is on the internet may not apply or be less cost effective. I hope everything goes well for you.
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.
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.
At least 2/3 of the insulation hast to been on exterior walls. Ex put 100mm insulation outside, max 50mm on inside. The insulation on exterior walls are offcors not exposed to water because you lay plastic sheet and mass with draining in bottom.
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.
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!
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.
I have seen people installing the foam with a little space between the foam and the wall. They just place the foam with big spots of adhesive in the corners. I guess it is to let the air flow upward and let it get out from the ventilation. Is this a good idea?
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
The only basement wall vapor barriers that work consistently are installed on the outside. I also like the insulation on the outside, rigid with oriented strands and back-filled with gravel. Good perimeter drainage is critical.
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 . 🇨🇦👍
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.
@@kenwarner5387 I'm in Canada and have seen several to code basements with vapor barrier/insulation that lead to moisture/mold build up. Just because something is code doesn't mean it's the best way to go.
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.
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
And I was wondering about using 3 to 6 in of gravel underneath the concrete as a way of keeping moisture away from the concrete or placing the gravel on the side as the fill in
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.
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
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
We’re not building a basement, but building above grade using Superior Walls (SW). These are precast 5000 psi precast concrete walls with R19 foam board built in. I was planning on using dense pack cellulose in the stud bays, however SW says that anything other than closed cell foam needs careful management of interior humidity. We will have an ERV, and a vapor retarder in the ceiling with R50-60 cellulose in the attic. My conundrum is whether to use a retarder or barrier on the exterior walls. I’d be interested in anybody’s thoughts on this.
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 )
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.
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 I’m working and spray foam business and what you say is right you 100% right because two different chemicals open and close close is the best open and you have a special and the attic never thing is too much
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!
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.
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.
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.
Is foil faced polyiso foam suitable for below grade applications against a poured concrete wall? Would the foil act as a vapor barrier and prevent any inward drying as apposed to unfaced XPS (oe similar) that would allow inward drying?
@@davidp2966 If the polyiso is on the interior side it works, but it doesn't fair well if it is buried below grade on the exterior. I'm assuming you meant if it was applied to the interior side of the foundation wall. It's okay if there is a vapor retarder against the concrete, as long as any framed walls are able to dry to the interior unimpeded, you'll be in good shape.
@@ASIRIDesigns Thanks for the reply! Yes, I did mean on the inside of the concrete on the basement wall. My concern is that foil changes it from a vapor retarder to a vapor barrier. I've heard mixed opinions on this. Some have said that having the foil (facing the interior) does not allow moisture coming from/through the concrete to dry to the inside the same way non faced will. I'm just trying to learn the best practice.. I would prefer to just used the usual pink/blue XPS like most people do but I found that the foil faced polyiso is significantly cheaper than XPS. If theres little difference, I might go with the polyiso instead.
I installed the rigid foam outside the concrete wall over an exterior impermeable membrane as I have seen done on some large construction projects. What are the negatives on this approach.
@@williamtait3700 This is a great approach, the only downside is ensuring the long-term durability of the rigid foam and keeping bugs away from it. Apart from that, it works great.
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...
@@CROSSofIRON-uki 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
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!
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.
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
Thank you for the info, just starting our basement project, we have the design and hired a framer, it is a walkout basement, the main wall is large glass windows and sliding door, the back walls are concrete, while both sides, our exterior walls. must I use a vapor barrier on the concrete side? Or all the way around, or not at all
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?
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.
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.
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?
Great job on this video! Just had to "un-finish" a finished basement that had massive black mold due to plastic vapor barriers. I think it's insane to finish a basement in anywhere other than a desert. Digging up the ground to pour the foundation and run off from the roof means basements will always be damp/humid... perfect for mold. I would never build a home with a basement or finish a basement. You're better off with an above ground addition, if you're already stuck with a basement - cheaper in the long run.
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?
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.
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 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.
Having air flow throughout the house is a better way to go. No air movement equals bad air condensation and mould. Even to much insulation can cause severe problems in a house.
Call me crazy, but when I finished my basement I did not like the idea of putting insulation directly on the cement walls. So, what I did was put a 9mm plastic from the top sill to the bottom of my stud walls. I made sure to wrap the 9mm plastic under the studs on the bottom of my interior walls. I then put R19 insulation in the cavities of the wall, I felt that with the 9mm plastic being directly up against the foundation the insulation wouldn’t get damp or wet. I then finished my walls with Sheetrock and some knotty pine over the Sheetrock for some accent walls. It’s been at least 30 years and I’ve never had a dampness problem or mold anywhere. I do run a dehumidifier in my basement always, as I feel every basement should have a dehumidifier in it. Cement is porous by nature and with a basement being sometimes 5-6-7, or even 8 feet unground you should always use a dehumidifier in those conditions. Just my opinion.
I'm planning to do exactly what you did. I actually just finished putting in an interior french drain with dimple matting coming 4" up the wall at the base. I'm planning on putting 6-9 mul moisture barrier from sill plate down and run it behind the dimple matting at the base. Does this sound like it will work? Do I still need a vapor barrier alsalsohad water coming through both the walls and the cold seem where the floor meets the walls. I also run a dehumidifier always, keeping it under 55% humidity all the time.
@@brianhawthorne8480 I just did what I did because like I said I never liked the idea of insulation sitting right up against the foundation. Cement is porous by nature and the foundation being underground it is always going to be damp. With a 9 mil plastic right up against the foundation walls, then your studs and insulation over that prevents anything from ever getting damp. That’s just my opinion. It won’t prevent the water or dampness from getting in, however it will keep it from hitting the insulation and studs. It’s been at least 30 years and I’ve never had a problem, however, I do recommend always running a dehumidifier in any basement. Good luck.
@@rickpacheco8864 exactly. Moisture will always come through a bit. But the poly should stop it. I was just wondering if there is ever a problem with retaining moisture between the poly and the concrete/cinderblock wall. Either way, I'm just gonna do it. If it fails it fails. 😂
@@brianhawthorne8480 well, to answer your question I have never had to open anything up because I have never had a problem. I don’t see any signs of dampness, or any damp moist smells that you usually smell or see when you walk into a basement. My walls are finished with drywall, and I even have some notty pine accent walls over the drywall. When I go in my utility area where a part of my wall and floor isn’t finished it gives me a good chance to always look around, and everything looks good. Like I said it’s been a good thirty years and I haven’t had one problem. I’m old school, keep the moisture from hitting the insulation and wood and I think that’s the way to go, it’s worked for me.
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.
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.
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.
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
Wow, what an awesome video!! I agree completely with everything you have said, however building code in southern Ontario will not allow you to not have a vapour barrier - you will fail building inspection. I wanted to ask a question, if you are to use a sub floor system like dricore (plastic bottom not foam) - would you install before or after the outside walls? Why?
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)???
I am right now searching how to limit radon getting inside my basement from the joint of my basement slab and basement walls. Those foam panels are unfortunately a chimney letting radon inside my basement. I don't know how to tackle the problem.
To address radon you need to do two things: Keep the radon out by ensuring that you're providing an adequate air barrier at the pressure boundary between the foundation and the conditioned space, and a means of radon removal, which is usually a passive or active subslab depressurization system. You don't want your home to be negatively pressurized, otherwise you're sucking soil gasses into the house. The house should be pressure balanced, or slightly positively pressurized in this case.
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! :)
What about house wrap first against the concrete wall then studs then insulation then vapor barrier Then drywall? House wrap sheds water one way but breathes the other way so needs to be installed just like you would on the sheathing on the main floors Staple it to the plates at the top first to hold it up 🙂
If you put your rigid foam insulation on the outside of the concrete, you don't have to worry about what it's going to do if you ever have a house fire, and your concrete thermal mass is now inside your thermal envelope. Then, put some drainage around the outside of your house already - there's not excuse for having dirt against the foam or the concrete when you have so many options in gravel and slotted pipe to take the water away. After that, make sure there's an air gap between the concrete and the timber, and run a dehumidifier through this space. Obviously you still don't want any electrical outlets or other holes in the wall lining on these outside walls, but a small dehumidifier and a fan to keep the air circulating is cheap insurance against anything going wrong.
Depends on the climate and nothing else. If you are in the south, where inside temperatures are below ambient ground temp then the vapor barrier must be outside or you must allow the wall to breath to the inside. If you. Are in Canada where the inside is always warmer than outside, then the vapor barrier must be inside. You must never however, put a vapor barrier on both sides of the wall.
Ive always framed basement walls about an inch off the foundation, then insulated and vapour barriered the wall frame. It leaves enough space for the concrete to breathe behind the insulated wall. Ive never had a problem, but ive also never ripped a wall apart that ive done this way.
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 seal the concrete from the outside and inside. No wood framing in contact with concrete walls. Floor sill is treated and a nervous draw material between. People are going NASA and it's overkill for no benefits.
Wow hang on you are getting off topic here a bit. It’s not just basements a vapour barrier is installed on all outside walls it stops condensation but also helps keep hot and cold air on the outside of the home. It’s not just used in basements but in all outside walls on every floor of the house including ceilings that cover attic spaces. If you are developing mold your house as an air flow issue. If your house ain’t breathing correctly mold will grow. It’s important to make sure the attic is vented properly you have to have soffit vents and roof vents the furnace needs to have a proper air return in all rooms of the house and filters need to be changed periodically. If your growing mold it’s not because of the vapour barrier.
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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!!!
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..
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.
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.
You may want to look up waterproofing foundations contractors. These details work even with PWF. They excavate foundation outside and apply a barrier, install weeping tile, and or regrade. PWF: = permanent wood foundations> they are required to have these details done rightby code. Concrete is more forgiving. I imagine your foundation isn't damaged structurally d, but you have water leaking in.
@@mrgregweber Indeed. I just had all the pipes under the concrete slab re-done. Sewer and storm drain now redirected to PVC pipes rather than aged cast iron. Internal french drain has been redone. All sloping towards drains that exit the house. Removed sump pumps which were not working well. Next step in the process is that I will be having the exterior of the home waterproofed - following ASIRI (and structural engineer) guidance of membrane, dimple board, insulation board, gravel, and exterior drain as well. Have to wait until spring for the landscape regrade, but that will be the final piece. The foundation continued to settle while the plumbers were excavating internally and installing pipe through the foundation walls. My guess is that there was sufficient presssure built up over time with failed pipes leaving excess water at the foundation, etc. And it released with excavation. Footer is concrete; foundation walls are concrete block. There are cracks in the block and mortar joint cracks on the exterior...and some cracked bricks. I was onsite for all of the interior work. I could see water coming in through prior installed weep holes. And during heavy rains, a bit too much water came through the weep holes in my opinion - but my experience in this area is quite limited. Structural engineer indentified that the exterior waterproofing will strongly mitigate the internal seepage (hopefully bringing it to a "drip") and that the internal drain will act as an emergency backup should anything get past the external waterproofing.
@@julibark713 It sounds like you are talking to local professionals. Accredited local professionals are always needed as areas differ and accordingly have different code. Some areas even have code that needs updating so you really need to rely on good pros. What is on the internet may not apply or be less cost effective. I hope everything goes well for you.
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.
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
At least 2/3 of the insulation hast to been on exterior walls. Ex put 100mm insulation outside, max 50mm on inside.
The insulation on exterior walls are offcors not exposed to water because you lay plastic sheet and mass with draining in bottom.
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.
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!
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.
I have seen people installing the foam with a little space between the foam and the wall. They just place the foam with big spots of adhesive in the corners. I guess it is to let the air flow upward and let it get out from the ventilation. Is this a good idea?
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.
Probably the most underrated building engineering channel.
Don't worry, the channel is gaining a lot of traction as it should :) cheers!
The only basement wall vapor barriers that work consistently are installed on the outside. I also like the insulation on the outside, rigid with oriented strands and back-filled with gravel. Good perimeter drainage is critical.
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 . 🇨🇦👍
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.
Flawed video. Seems to be pushing to fail inspection and never obtain insurance. Wasted my time watching
@@kenwarner5387 I'm in Canada and have seen several to code basements with vapor barrier/insulation that lead to moisture/mold build up.
Just because something is code doesn't mean it's the best way to go.
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.
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
And I was wondering about using 3 to 6 in of gravel underneath the concrete as a way of keeping moisture away from the concrete or placing the gravel on the side as the fill in
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.
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
Thank you for the statement.
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
We’re not building a basement, but building above grade using Superior Walls (SW). These are precast 5000 psi precast concrete walls with R19 foam board built in. I was planning on using dense pack cellulose in the stud bays, however SW says that anything other than closed cell foam needs careful management of interior humidity. We will have an ERV, and a vapor retarder in the ceiling with R50-60 cellulose in the attic. My conundrum is whether to use a retarder or barrier on the exterior walls. I’d be interested in anybody’s thoughts on this.
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 )
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.
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 I’m working and spray foam business and what you say is right you 100% right because two different chemicals open and close close is the best open and you have a special and the attic never thing is too much
People don't care and additionally believe that PVC vinyl is safe because the APC American Plastics Council is shoving it down their throat
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!
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.
so if you are building an ICF basement should you tape seems in foam blocks
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.
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.
Is foil faced polyiso foam suitable for below grade applications against a poured concrete wall? Would the foil act as a vapor barrier and prevent any inward drying as apposed to unfaced XPS (oe similar) that would allow inward drying?
@@davidp2966 If the polyiso is on the interior side it works, but it doesn't fair well if it is buried below grade on the exterior. I'm assuming you meant if it was applied to the interior side of the foundation wall. It's okay if there is a vapor retarder against the concrete, as long as any framed walls are able to dry to the interior unimpeded, you'll be in good shape.
@@ASIRIDesigns Thanks for the reply! Yes, I did mean on the inside of the concrete on the basement wall. My concern is that foil changes it from a vapor retarder to a vapor barrier. I've heard mixed opinions on this. Some have said that having the foil (facing the interior) does not allow moisture coming from/through the concrete to dry to the inside the same way non faced will. I'm just trying to learn the best practice.. I would prefer to just used the usual pink/blue XPS like most people do but I found that the foil faced polyiso is significantly cheaper than XPS. If theres little difference, I might go with the polyiso instead.
I installed the rigid foam outside the concrete wall over an exterior impermeable membrane as I have seen done on some large construction projects. What are the negatives on this approach.
@@williamtait3700 This is a great approach, the only downside is ensuring the long-term durability of the rigid foam and keeping bugs away from it. Apart from that, it works great.
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?
@@CROSSofIRON-uki 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
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!
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.
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
This is why ICF works so well in the basement. Concrete is insulated and no further vapour barrier.
Thank you for the info, just starting our basement project, we have the design and hired a framer, it is a walkout basement, the main wall is large glass windows and sliding door, the back walls are concrete, while both sides, our exterior walls. must I use a vapor barrier on the concrete side? Or all the way around, or not at all
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.
Please note that if the resin used on mineral wool is organic, mould will proliferate on that resin, conditions permitting.
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.
Half inch or 1 inch foam boards for basement foundation walls?
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.
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!
Isn't there a paint barrier that you can spray on the outside that acts as a moisture barrier ?
Would the intello membrane work for the basement concrete slab as well?
Do you design residential buildings, or have a catalog I could look at purchasing plans from?
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?
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 job on this video! Just had to "un-finish" a finished basement that had massive black mold due to plastic vapor barriers. I think it's insane to finish a basement in anywhere other than a desert. Digging up the ground to pour the foundation and run off from the roof means basements will always be damp/humid... perfect for mold. I would never build a home with a basement or finish a basement. You're better off with an above ground addition, if you're already stuck with a basement - cheaper in the long run.
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
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
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.
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 dont leave comments using my main account, but this was a good video. Thanks for sharing, specially because we just redid our basement
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.
Interesting where are you located?
@@markmartin7384 New England. Pretty sure the foundation is sealed from the outside as well, so that makes a big difference.
Having air flow throughout the house is a better way to go. No air movement equals bad air condensation and mould. Even to much insulation can cause severe problems in a house.
Don't you also need to have an air barrier around the joists when you use rigid foam?
Even better move is put Rigid foam board on the OUTSIDE basement walls ❤ all the way down to the frost line.
Call me crazy, but when I finished my basement I did not like the idea of putting insulation directly on the cement walls. So, what I did was put a 9mm plastic from the top sill to the bottom of my stud walls. I made sure to wrap the 9mm plastic under the studs on the bottom of my interior walls. I then put R19 insulation in the cavities of the wall, I felt that with the 9mm plastic being directly up against the foundation the insulation wouldn’t get damp or wet. I then finished my walls with Sheetrock and some knotty pine over the Sheetrock for some accent walls. It’s been at least 30 years and I’ve never had a dampness problem or mold anywhere. I do run a dehumidifier in my basement always, as I feel every basement should have a dehumidifier in it. Cement is porous by nature and with a basement being sometimes 5-6-7, or even 8 feet unground you should always use a dehumidifier in those conditions. Just my opinion.
I'm planning to do exactly what you did. I actually just finished putting in an interior french drain with dimple matting coming 4" up the wall at the base. I'm planning on putting 6-9 mul moisture barrier from sill plate down and run it behind the dimple matting at the base. Does this sound like it will work? Do I still need a vapor barrier alsalsohad water coming through both the walls and the cold seem where the floor meets the walls. I also run a dehumidifier always, keeping it under 55% humidity all the time.
@@brianhawthorne8480 I just did what I did because like I said I never liked the idea of insulation sitting right up against the foundation. Cement is porous by nature and the foundation being underground it is always going to be damp. With a 9 mil plastic right up against the foundation walls, then your studs and insulation over that prevents anything from ever getting damp. That’s just my opinion. It won’t prevent the water or dampness from getting in, however it will keep it from hitting the insulation and studs. It’s been at least 30 years and I’ve never had a problem, however, I do recommend always running a dehumidifier in any basement. Good luck.
@@rickpacheco8864 exactly. Moisture will always come through a bit. But the poly should stop it. I was just wondering if there is ever a problem with retaining moisture between the poly and the concrete/cinderblock wall. Either way, I'm just gonna do it. If it fails it fails. 😂
@@brianhawthorne8480 well, to answer your question I have never had to open anything up because I have never had a problem. I don’t see any signs of dampness, or any damp moist smells that you usually smell or see when you walk into a basement. My walls are finished with drywall, and I even have some notty pine accent walls over the drywall. When I go in my utility area where a part of my wall and floor isn’t finished it gives me a good chance to always look around, and everything looks good. Like I said it’s been a good thirty years and I haven’t had one problem. I’m old school, keep the moisture from hitting the insulation and wood and I think that’s the way to go, it’s worked for me.
@@rickpacheco8864 Great. Thanks for your help!
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.
I’ve been running a dehumidifier in my basement for about 10 years now. Huge huge huge difference.
How about insulating it from the exterior side? Wouldn't that be simpler if it were a new build?
Inspector in my area makes us valor barrier even with the foam board behind the framing
Excellent explanation thank you!
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!
Love all the graphics and clear information
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.
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.
Excellent explanation
This is quickly becoming ym favorite channel for building science. I hope you keep on keeping on. I like being an educated GC.
Even more better IMO would be to install Pordrän or Isodrän on the outside basement wall!
what about off gassing?
I'm not 100% sure I understand.
So it should be...
Concrete -> Rigid Foam -> Vapor Barrier -> Framing+Batt -> Vapor Barrier -> Drywall
?
Wow, what an awesome video!! I agree completely with everything you have said, however building code in southern Ontario will not allow you to not have a vapour barrier - you will fail building inspection. I wanted to ask a question, if you are to use a sub floor system like dricore (plastic bottom not foam) - would you install before or after the outside walls? Why?
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)???
I am right now searching how to limit radon getting inside my basement from the joint of my basement slab and basement walls. Those foam panels are unfortunately a chimney letting radon inside my basement. I don't know how to tackle the problem.
To address radon you need to do two things: Keep the radon out by ensuring that you're providing an adequate air barrier at the pressure boundary between the foundation and the conditioned space, and a means of radon removal, which is usually a passive or active subslab depressurization system. You don't want your home to be negatively pressurized, otherwise you're sucking soil gasses into the house. The house should be pressure balanced, or slightly positively pressurized in this case.
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! :)
Great video, well made.
my unfinished old basement was leaky damp dried out quickly
👍🏻👍🏻 thank you, very good info!
Thanks Sharif!
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.
What about house wrap first against the concrete wall then studs then insulation then vapor barrier Then drywall? House wrap sheds water one way but breathes the other way so needs to be installed just like you would on the sheathing on the main floors Staple it to the plates at the top first to hold it up 🙂
@@thegrantdanielsband No. Watch my latest Q&A where I address this: th-cam.com/video/9yoGFX_1gjQ/w-d-xo.htmlfeature=shared
If you put your rigid foam insulation on the outside of the concrete, you don't have to worry about what it's going to do if you ever have a house fire, and your concrete thermal mass is now inside your thermal envelope. Then, put some drainage around the outside of your house already - there's not excuse for having dirt against the foam or the concrete when you have so many options in gravel and slotted pipe to take the water away.
After that, make sure there's an air gap between the concrete and the timber, and run a dehumidifier through this space. Obviously you still don't want any electrical outlets or other holes in the wall lining on these outside walls, but a small dehumidifier and a fan to keep the air circulating is cheap insurance against anything going wrong.
Depends on the climate and nothing else. If you are in the south, where inside temperatures are below ambient ground temp then the vapor barrier must be outside or you must allow the wall to breath to the inside. If you. Are in Canada where the inside is always warmer than outside, then the vapor barrier must be inside.
You must never however, put a vapor barrier on both sides of the wall.
Ive always framed basement walls about an inch off the foundation, then insulated and vapour barriered the wall frame. It leaves enough space for the concrete to breathe behind the insulated wall. Ive never had a problem, but ive also never ripped a wall apart that ive done this way.
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?
Instead of a wall how about curtains? Deaden sounds, washable, and simple to inspect for leaks.
So complicated! Put 4” of SM board outside against the dirt and concrete. Done.
Thanks for sharing!
Or use ICF foundations and you do not need to worry about any of this. Also cheaper.
Rule of thumb: don’t install impermeable layers without an moisture “exit”?
Learn from Norway. No vapour barrier if more then a half of walls are UNDERGROUND. Insulate from outside with the XPS.
Or, do all foundations with icf
I seal the concrete from the outside and inside. No wood framing in contact with concrete walls. Floor sill is treated and a nervous draw material between.
People are going NASA and it's overkill for no benefits.
Avoid basements and crawl spaces of you can...
Wow hang on you are getting off topic here a bit. It’s not just basements a vapour barrier is installed on all outside walls it stops condensation but also helps keep hot and cold air on the outside of the home. It’s not just used in basements but in all outside walls on every floor of the house including ceilings that cover attic spaces. If you are developing mold your house as an air flow issue. If your house ain’t breathing correctly mold will grow. It’s important to make sure the attic is vented properly you have to have soffit vents and roof vents the furnace needs to have a proper air return in all rooms of the house and filters need to be changed periodically. If your growing mold it’s not because of the vapour barrier.