Moisture barriers are essential for preventing water and moisture from entering basement walls. They fall into three categories based on their permeability, measured in units called “perms”. The lower the perm rating, the less moisture the barrier allows through. Before framing the walls of your basement, install a moisture barrier to prevent water and moisture from entering the wall cavity.
Building codes usually require a vapor barrier (4 mil plastic sheeting) on exterior basement walls if the framing is attached to masonry or concrete surfaces, or if the basement living spaces have finished walls. Most municipalities require basement living spaces to have finished walls, with detailed requirements for construction that include reaching specific R-values (insulation), incorporating moisture protection, and more.
A basement vapor barrier is a great way to keep the area dry and comfortable by reducing the amount of moisture coming through. It helps prevent mold and mildew growth, eliminate musty smells, reduce energy bills, and lower the entire home’s humidity level. However, it is not necessary to put a vapor barrier on the interior of a basement wall, as the interior air is not where the dangerous moisture is.
Plastic barriers are not necessary but should not cause any harm unless they create a “moisture trap” on the interior side of the wall. Placing a vapor barrier on the interior side can lead to mold or rot, so it is proper to waterproof the walls. A vapor barrier on the basement walls is an important part of finishing your basement, protecting water leaks from wall ties or cracks.
📹 Moisture Barrier – 3 Types
Please note that the house wrap product should be reversed from what is shown here in video. Place the side with writing on it …
When not to use vapor barrier?
Vapor barriers are essential for various purposes, such as waterproofing concrete basement walls, preventing gas and radon emissions, and providing mold barriers. However, they should not be used to waterproof a failing concrete wall. Vapor barriers are low-permeable, meaning they can trap moisture behind them if installed on a water-damaged wall, causing further failure. Proper tape should be used when stapling or nailing them, and 6 mil barriers should not be used in a crawl space used for storage.
Vapor barriers should be placed on the bottom of the floor joist in the crawl space. If the wall fails due to a leaking water source, the source should be repaired. Therefore, builders and contractors should consult their local building code requirements when determining the appropriate use of vapor barriers.
Is it better to insulate basement walls or ceiling?
Basement ceiling insulation can be used for living space and energy bill reduction. However, it’s crucial to insulate the basement walls to prevent air leakage and vapor from overworking the HVAC system. Basement walls act as a barrier between the cold outside ground and the home, and insulation can solve various problems, such as sound control and temperature control. Closed cell spray foam is the best option for temperature control and lowering energy bills, while open cell spray foam insulation and other soundproofing products are better for sound control.
Are you supposed to insulate interior walls?
Interior walls are typically not insulated during construction, but they can still play a role in a home’s energy efficiency. Although not as significant as exterior walls, insulation can still be a wise investment for homeowners. Most homes already have some level of insulation, but modern materials or techniques can improve efficiency. Insulating interior walls can regulate temperatures, especially in rooms used infrequently or closed off for parts of the year.
It also offers noise control by soundproofing interior walls, which can keep everyone comfortable and peace. Additionally, insulation can protect against moisture problems, such as condensation in rooms with regular water use, such as the bathroom and kitchen. By separating different air temperatures, slowing heat transfer, and reducing moisture problems, insulation can help prevent mold or mildew growth. Contact One Hour Heating and Air Conditioning for an in-depth examination of your home’s HVAC system and insulation.
What is the difference between a moisture barrier and a vapor barrier?
Moisture and vapor barriers are essential for keeping moisture out of your home, with moisture barriers being better at preventing liquids and vapor barriers being better at preventing water in its gaseous state. Materials for moisture barriers can be classified into three categories based on their permeability rating, as defined by the International Residential Code. Class 1 covers vapor barriers with the lowest permeability, such as metal, glass, and polyethylene sheets. Class 2 covers extruded polystyrene and plywood, while Class 3 includes materials like gypsum board, concrete blocks, and house wrap.
While it’s crucial to prevent mold infestations and moisture damage before they occur, it’s not always possible to address them yourself. If water damage has already occurred and mold is visible, it’s likely severe. Mold infestations usually start inside porous materials and don’t spread until a large mold colony is established.
Do I need to insulate interior basement walls?
Insulation is crucial for concrete basement walls to meet building codes and prevent issues like cold floors and drafts. Not all basements require wall insulation, as the situation depends on the home’s intended use. Wall or ceiling insulation is necessary for two critical areas of the basement: the walls and the ceiling. It’s not necessary to insulate both walls and the basement ceiling, but choose one to ensure proper insulation. This will help prevent drafts and maintain a comfortable living space.
How do you waterproof basement walls from inside?
If a foil test confirms water seepage in basement walls, remove existing paint and seal the interior with a waterproof product. This creates a watertight bond, preventing water seepage. Gutters and downspouts channel water away from the house, maintaining structural health. If you lack gutters or sump pumps, consider adding them. If already installed, fasten metal or plastic extensions to capture runoff or excess water and drain it away from the base.
Should you waterproof interior basement walls?
Water seeps through cracks and pores in concrete walls, leading to a wet basement. This issue is more likely in areas prone to heavy rainfall, snowstorms, or snow melts. Water seepage can cause significant damage to the interior spaces of a home, affecting its structural integrity and value. To prevent basement water flooding, homeowners should take immediate preventative actions and invest time and effort in maintaining the home’s condition.
Interior basement waterproofing involves waterproofing basement walls from the inside, re-routeing water leaks before it can enter, exit, and away from the home. This is an effective and less offensive alternative to exterior waterproofing. A waterproof sealant is used to close all cracks and pores in the walls, making it an effective and less offensive method.
In conclusion, homeowners should take immediate preventative actions to prevent basement water flooding and consider the best waterproofing method for their home.
Do interior walls need moisture barrier?
Mold thrives in damp conditions, and moisture buildup in hidden areas can lead to health issues and costly repairs. Moisture barriers help keep these areas dry, reducing the risk of mold growth. Key areas where moisture barriers are typically installed include basement floors, crawl spaces, exterior walls, and under flooring. For basement floors, a polyethylene sheet should be placed under the concrete slab to prevent moisture seeping up.
For crawl spaces, a heavy-duty polyethylene sheet should be installed over the entire floor, extending up the foundation walls by about 6 inches. For exterior walls, moisture barriers should be placed on the warm side of insulation or on the cool side in hot, humid climates.
Do interior walls need waterproofing?
Interior wall waterproofing is crucial in construction projects as it safeguards walls from moisture and water damage. There are various products available for this purpose, including concrete sealers, liquid membranes, sheet membranes, and elastomeric coatings. Concrete sealers prevent water penetration and are suitable for both new and existing structures. Liquid membranes are a two-part system consisting of a primer and an acrylic or epoxy coating, repelling water and preventing moisture buildup.
Sheet membranes, on the other hand, are impermeable sheet materials applied onto the wall surface, providing superior protection against water damage in wet areas like bathrooms. These products offer a range of colors and finishes to enhance the aesthetic appeal of your space.
What is the difference between a vapor barrier and a moisture barrier?
Moisture and vapor barriers are essential components in insulation systems, with moisture barriers installed on the warm side of the wall and vapor barriers placed on the exterior or interior. Weather barriers prevent moisture, rain, and wind from passing through the building envelope but also allow water infiltrating the wall system to dry out quickly. Properly installed vapor barriers can also act as air and water barriers, making them non-permeable.
Spray-applied and sheet-applied air barriers are reliable systems, but the choice depends on project conditions and personal preferences. Spray air barriers are easy to apply and lessen labor needs, but their success depends on using a consistent and correct spray thickness. Additionally, it is important to monitor weather conditions and avoid using spray or roller-applied products if rain is expected, as they may not have adequate time to cure.
Sheet-applied membranes have application thickness issues but can present challenges such as labor-intensive installation, complex application on uneven substrates, and the need for a primer in some cases.
Do you need a vapor barrier on interior basement walls?
It is of the utmost importance to implement vapor and moisture barriers in order to safeguard one’s domicile from the detrimental effects of water damage. It is advisable to seek the guidance of a professional contractor prior to the installation of a vapor barrier in your basement. Vapor barriers are an effective solution for addressing moisture problems; however, in areas where such issues are not present, leaving them off may be the optimal choice.
It is similarly crucial to engage in regular tuckpointing as part of a comprehensive home maintenance program. This practice is essential for the protection of a residential property from the damaging effects of water.
📹 The Ugly Truth About Basement Vapor Barriers
Installing a vapor barrier in the wrong location in a basement wall can end up trapping moisture in the wall assembly and …
The air vapor barrior paper sheets are for more preventing water in air moisture… the moisture barrior is more for preventing larger amount of foundation leaking water from outside in. Not the smaller issue of water from air humidity… thats why attics uses paper air barriors on the floor then the insulation rollout. The moisture barrior is more for foundations or bathrooms where larger amounts of water due not only humidity but water itself sources.
If I use rigid foam as the moisture barrier, do I still need to have batt insulation or is the rigid foam enough insulation for my basement? I live in the northeast so it get’s cold. Also how is the rigid foam attached to the foundation? Does the rigid foam go from very top of the wall to the bottom or is there a gap on the top? Only 80% of my basement is below grade so wondering if I can skip the top 20% which is above grade. Last question, how does my wood frame attach to the rigid foam or is there a gap between the two? TIA
I have a brick house with 2×3 studs throughout. Im going to tear down the walls and put in roxul insulation and drywall over it. between the studs and outside wall is some tar paper or whatever they call it. Im wanting to put a vapor barrier over the roxul insulation. is that ok? also i’m in North Carolina.
Hi Shannon, One question I am refinishing Basement in end Condo Unit and plan of using 1″ Fiberboard per your article on the three cement basement walls the see the exterior. The 4th basement wall separates my end condo from the next condo unit over. Is it necessary to fiber board the wall as well since it an interior wall. I don’t think the next unit is finished or heated. At the very least I was thinking of putting a lower level of moisture barrier like sheathing to save some money. Is this needed. Your thoughts and feedback would be appreciated. Thanks, Don
I have a few questions I’m about to renovate my basement and will be doing the following. For the tyvek wrap is the writing suppost to face outside against the wall? And my basement is already finished but will be ripping out the walls and redoing the insulation before drywall.. It doesn’t have rigid foam board, is it even possible to add because its already framed?
Thanks for another great article! I’m installing a new upstairs bathroom and have a little penetrating damp through a stone chimney wall. The chimney is fully ventilated with a ventilated hood on the chimney pot, but some winter rain soaks through the render outside. Builders say there’s no more we can do to improve it, so using your method I plan to add a moisture barrier with drainage for any dripping condensation. We don’t have much room for thick studwork so I wondered : 1) Can the batten can be installed vertically 600mm apart 2) Moisture barrier stapled to the batten 3) A 2nd batten screwed on top of the first (possibly at 90 degrees) 4) Thin rigid foam added between the 2nd battens 5) Finished with a layer of vapour barrier sheetrock Really appreciate your advice, keep up the great work!
Great article. Thankyou. Here is a about a wood floor? I have a thin wood floor in a garage, not insulated underneath. I want to stop moisture from coming in. It will have a new layer of 3 quarter inch plywood on it with 1 inch rigid foam under that. But doninput moisture barrier first? And donI spray foam all along the edges too? It’s a 320 square foot garage turning into a mancave
I am using plastic for the moisture barrier, and not sealing it. People keep telling me that it is going to create moisture. . . But if it isn’t sealed is this a problem? We will be installing an airtight vapour barrier too. I don’t want to have to rip up my walls 6 months after finishing the whole project. Where does the moisture go?
Let’s assume there is a moisture problem. Does that mean mold will be growing behind the purple board for all the years you live in the basement? If so, is the purple board good a genuinely protecting you from that condition? I am also assuming there is no access on the other side of the concrete, which is obviously how you would want to fix it; at the source. In cities, often there is no access on the exterior concrete. THANKS!
Thank you Shannon. I was especially glad to see your comment of placing the lettering of the house wrap towards the concrete wall as house wrap is kind of like Gortex – repels the moisture on the lettering side but allows vapour to pass from the other side (inside the home) outward. All too often people get this wrong and they set themselves up for a mess i.e. mold. Nice to have you as a one stop site to get all the information accurately. Ottawa, Canada
10 yrs ago the inspector had me wrap cinder block wall with 6mm poly down cinder block face into drain tile opening and face glue it shut. Then build 2×4 wall 2 inches in front of it with r13 batting and then covered with 6mm poly glued to bottom plate and taped. Today I’m removing 120 ft of knee wall in the basement because it’s completely soaked on the face of the inner poly (during MN winter.) It ruined the batting, smells like heck and now I need a bunch of money. I told him I was going to do 2 inch xps foam and he told me to just use poly for inner and outer. The new inspectors now are telling me that was bad information and I need to remove the cinder block poly completely and leave the drain tile open and just reset my knee wall back in place keeping it 2 inches from the block, re-batt it with backer strips keeping it away from block, and 6mm poly the face then rock. So basically, they want me to just subtract the block wall poly. I know double lock is the reason but should I do this? Or go with 1.5 inch xps sealed to block, then wall it ? Thanks !
Thanks for the article. so, for spray foamed basement we don’t need any vapor or moisture barrier to be installed before framing? and for floor base plate where foam is not sprayed, what we need to do? I do see that in my basement, foam is sprayed a little bit on the floor as well where baseplate is placed.
I don’t have any leaks my basement walls just gets mouldy I have recently put a dehumidifier down there so it doesn’t smell mouldy anymore but the is no visible water coming in so I have cleaned up what mould I did have and paint ed with a mould resistant paint now I want to put the foam frame and drywall
Thank you, I just learned that the “Vapor” barrier and “Moisture” barrier are not the same. Years ago I was told by a carpenter that us folks up north put ‘the’ heavy mil plastic barrier on the inside of the walls and down south it goes on the outside. So I guess since then things have changed since there are two products that separately address vapor or moisture. I recently moved and will start framing in my basement walls. Since they are painted cement blocks and appear to never have had any water leaks or stains do I still need the moisture barrier? Harry
I really don’t understand how rigid foam or foam applications that are bassically air tight to the concrete are acceptable if the wall is supposed to breath… wouldn’t these applications be trapping excess moisture in the block/concrete thus accelerating the deterioration of the wall? Or is that just thinking too much into it? I’m in Wisconsin, and I’m debating if I should use 1″ foam board and seal it all up good with tape and spray foam, or let it breath using 1″ rock wool comfort board. Then obviously framing and more insulation in the cavity. But to take it one more step I was even going to use the certianteed membrain vapor barrier to allow air flow between season changes. Anyone got some concrete evidence to the best approach? ( pun intended ) 🙂
i live in canada, we have a cold cellar on basement. and moisture build up during winter and summer. cold cellar has 2 6inches holes on both side. i want to to totally shut it down because of molds growth. my problem is the door between the cellar is moisture build on the door. im thinking to put a Eps or Polyiso foam board to prevent from condensation on the door if that will help to stop moisture grow. or ij the future need to close the 6inch holes and isulates the wall on cold cellar. please help me which best to do for now. planning to seal the door first for now if that one will work is better to use a polyiso board with foil on both side? pe go for eps?
Great article, it was helpful to understand the purpose of moisture barriers. But I have few more question, I will be grateful if you could address them. I am in process of installing Luxurt Vinyl Planks flooring (LVP) and manufacturer recommends to use moisture barrier for underlayment. What kind of moisture barrier would you recommend as underlayment for installing the LVP flooring? We have 3 level including a concrete slab on level 1 and we will install LVPs in multiple rooms including bathrooms. Will it be okay to use house-wrap paper everywhere or would you recommend to use plastic on concrete slab and high moisture rooms (bathrooms) and then house-wrap paper for rest of the areas?
Great article! I Just gutted my den and found lots of damage to my moisture barrier. it looks to be nothign more than very thick aluminum foil. The house was built in the 70’s so I guess that was code back then. I have a brick house and behind that damaged barrier was raw brick and nothign else. Can I replace that old school aluminum stuff with the rigid foam or should I hunt around for that same type of moisture barrier?
Hopefully someone can answer this question for me. So I see all these articles and articles about insulating basment interior with rigid foam and then framing in front of it. But I can’t seem to find info that claims that is fire safe. Is having drywall in front of it what makes it fire safe? I’m getting ready to insulate my basment cinderblock walls but don’t want to use XPS if it isn’t fire safe.
so the moisture from the living space wont make it past the overlaps? what about the moisture that comes thro the concrete wall will that tyvec still stop it? what about moisture that comes through the foam board? what would you do exactly if you were going to use the water gaurd that sits on the footer against the wall ?
In the case where my builder has already included insulation with the vapour barrier in the basement, do I rip it down and reinstall according to your instructions or do I just put up a wall in front of it and board it up? I don’t think the builder has included a moisture barrier between the basement concrete wall and the pink insulation.
Hi Shannon u have tried to ask this question on you forum but I got no answer I don’t know why so now I will ask here I am putting the 1″ thick foam board on my basement walls I get a lot of moisture in my basement witch get some mould I have cleaned it build up around the outside to help water run away so is it ok to put the foam board on even if I may still get a little water ? Sorry so long lol
Amazing articles…especially for a female DIYer. Hopefully you still see your messages for older articles. Quick question…I am putting up the 1in refective foam board on my cement wall but there is a metal water trap? that goes around the entire circumference on my basement floor. About 4in tall. Do I put the foam board over this trap to attach to my cement wall? Or leave this area open? Guess it’s used to collect any water discharge from the wall.
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.
Glad I saw this article 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.
Such an incredibly informative article. 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 article 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.
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 article first. Remember, the code is the minimum… always improve on it. This article explains the best ways. I see you advise EPS, but it has its hazards – off-gassing, and combustibility in particular
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.
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
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!
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.
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.
Used pink panther foam against the concrete block and then used a pvc bottom plate for the 2×4 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 2×4 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 )
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.
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!
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!!!
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 article 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 article makes though. Should I bust open a section to check, or just leave well enough alone?
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
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…
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! 🙂
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.
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.
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.
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 🙂