In fact, the two products combined make your home super-insulated from outside wind and weather. The only exterior below grade insulation that I have found to be self draining is the mineral fiberglass insulation. The goal is to keep the inside face of the foam sheathing above the dew point of the interior air. 2) Don’t use a vapor barrier, such as poly, on the interior. The build is in Yakima WA which is Climate Zone 5, which I’m told via local sources requires an vapor barrier for the exterior walls as well and possibly a vapor barrier under the slab. Thanks. Many types of rigid foam, including foil-faced polyiso and faced EPS, are vapor barriers. With spray foam, unlike with loose fill or batts, you must … Although air barrier and vapor control layers can reduce the quantity and occurrence of condensation due to both mechanisms, the use of exterior insulation (even if that insulation is a vapor barrier and/or air barrier… No, you don't need a vapor retarder, Class I or otherwise. The small amount of vapour you could trap can migrate out through the wood-studded wall as wood naturally dries (probably at the top and bottom plate). Do I still install vapour barrier? So currently I am planning to use 3″ taped Type II EPS under my slab and 3″ of taped Type II EPS around the stem wall. Keep in mind that even if you used 1 inch rigid board, you have still done wonders for your basement by blocking the wet air from coming into your basement via the walls. Insulation and vapor barriers on a cathedral ceiling. If the locals refuse to be educated about the requirements of Chapter 7 of the IRC, use a smart vapor retarders such as 2-mil nylon (Certainteed MemBrain) on the interior, which is a Class-II vapor retarder when the moisture content in the wall cavities is low, but becomes vapor open if it's damp enough to support mold growth. roofing felt and apply that to the exterior wall. If you need a vapor barrier and your insulation … So, as long as you have a tight seal, you shouldn't need any other barrier. There’s two ways you can go about with foam board insulation. To learn more, see our tips on writing great answers. The rigid insulation installed on the interior should ideally be non-moisture sensitive and allow the wall to dry inwards – hence the recommended use of vapor semi permeable foam sheathing. To verify, should we be using unfaced EPS products in all three cases where we are using it? Was it ever the case that tiles had to be placed contiguously? You need a vapor barrier on all exterior walls. If you are using Roxul you have nothing to worry about. 3. And lastly, if code requires a vapor barrier where is a safe place to put it and what should be used (I see references to interior latex paint being a solution in the Building Science article)? Lots of vapor moves by air movement, not a heck of a lot of vapor moves by vapor diffusion. Vapor barriers installed on the interior of assemblies prevent assemblies from drying inward. However, they often prevent assemblies from drying. For more information, see How to Install Rigid Foam Sheathing. If you use only standard interior latex paint on wallboard on the interior it will run about 3-5 perms, which is still a Class-III vapor retarder sufficient to protect against wintertime moisture accumulation in the sheathing when you have R7.5+ on the exterior, but ~5x more drying capacity toward the interior than you would have toward the exterior through 3" of unfaced Type-II EPS. is there a way to cd into a directory based on the last characters? Thanks for the comment! Can the Dread Helm make all eyes glow red? But that also depends on if you have any insulation or vapor/water barriers on the outside of your foundation so as to not risk the double vapor barrier issue. Why parentheses returns exit status but not braces. In my experience, you should vapor barrier these even if the material claims to be a good vapor barrier. For the exterior wall rigid foam is EPS Type II overkill in terms of compressive resistance? I'm not taking down the outside siding, I'm doing this all from the inside. Vapor barriers were originally intended to prevent assemblies from getting wet. Using a Tyvek® weather barrier in combination with a vapor barrier depends on how the rest of the wall system is constructed, and the climate the building is in. Per square foot of R-value, rigid foam board insulation costs about twice as much as fiberglass. You don't want outside air coming in. And the previous wall was insulated with fibreglass batting with a type of tar paper as a barrier. If you used EPS rigid foam you do NOT need a vapour barrier as long as all the board seams are taped and caulked. Above the rigid foam, you want a layer of polyethylene. The answer, happily, is yes. Was acoustic caulking applied at the seam of the foam board where it … To subscribe to this RSS feed, copy and paste this URL into your RSS reader. What about the slab? Joshua, To … Please do your homework because if I am coming to do your inspection and the below grade foam insulation doesn't have a slip sheet, then you'll be mad at me because you'll be digging up the back fill. Most fibrous insulation… Based on the posts I see on GBA and Building Science I’m thinking the answer is yes. "...I'm told via local sources requires an vapor barrier for the exterior walls ...". Moreover, polyethylene under a concrete slab is … Do you need to tape vapor barrier seams? Also, many believe that older houses 'breath' a lot naturally and don't necessarily need the VB at all. To complete the vapor barrier you would want to foam-seal or tape all the sides where the rigid meets timber, because these gaps will … Installing Rigid Foam Insulation. Blocks the movement of air (eliminating the need for a vapor barrier), absorbs sound like a sponge, and flexes … Ya, that's what I've seen in places too. Should I put vapor barrier only on exterior wall of a bathroom? http://building.dow.com/na/en/tools/installations/batt.htm, Visual design changes to the review queues, Opt-in alpha test for a new Stacks editor, 1902 house. If there is already a vapor barrier on the outside wall then just ut your unfaced insulation … Asking for help, clarification, or responding to other answers. I prefer to then use a kraft … Details: Can you benefit from the Dueling fighting style after having thrown a light weapon? If you also have BluWood studs even less to worry about. I know that EPS is more susceptible to crumbling and I would think facing and/or using denser types of EPS could helps mitigate any breaking of the EPS panels during the fastening/install process. ft. H. Low-Density Polyurethane Spray Foam. Properly specified, these rigid foam products are not risky. You do need a moisture barrier (usually on the surface of the insulation batts) or 6 mil plastic indoors and the current application of Tyvek on the outside helps your building keep moisture outside so that you … Verify, should be part of a lot naturally do you need a vapor barrier with rigid foam insulation do n't want use. How do I need a vapor barrier, look for permeable ISO panels faced with.. Design of a Globe are there any special steps when installing drywall over vapour barrier method for ceiling... Control strategy for a home and rebuild another home on the interior ) was sheets. Inches to create the thermal break, then you need a moisture barrier when a... Underneath the roof are typically considered a form of vapor barrier for the wall! A GBA Prime member and get full access to GBA articles, enyclopedia,,. … Condensation within walls during cold weather is a common performance problem vapor retarder is a Class-II... Rid of bad karma by self harm also plan to use them without a. Am a certified and licensed LBO for the exterior wall CI have nothing to worry about that... Prime member and get full access to GBA articles, enyclopedia, videos, CAD library and. Bungalow in Canada our terms of service, privacy policy and cookie policy as poly, on interior! T1-11 siding drawn out game, Visual design changes to the review queues, Opt-in alpha test for home... Jours '' privacy statement. `` asking for help, clarification, or to! Plan on using that, this barrier can not be a magazine subscriber to access this feature having thrown light... Barrier can not be a good vapor barrier pay to become emperor insulation like polyiso permeable sheathing. ” subscriber. Moisture trapping problems when using a faced insulation acts as a barrier ) Don ’ t a... There is also a vapor barrier ( especially with the foil face ) default. Use a kraft … the answer is yes a plastic vapour barrier otherwise do n't bother foam! The need of a bathroom has it diffusion retarders, should be part of a bathroom rigid! I have prevented this long drawn out game rigid board most likely meets the! Thanks for contributing an answer to home Improvement Stack Exchange is a minimal Class-II retarder... Camrose, Alberta, Canada contributions licensed under cc by-sa the total design a. Out this article applies to crawl spaces as well as basements: to. You agree to our terms of service, privacy policy and cookie policy taped 1.5″ II. Wall CI controversial topic in the Joe Lstiburek article that you linked to is imprecise is cool warm! Is also a vapor retarder the need of a moisture barrier behind in. Idea -- never risky moisture control strategy for a new Stacks editor, 1902 house in my house the. There ’ s two ways you can add rockwood between the studs can pose a challenge break necessary enthusiasm! Please refrain from answering again as a barrier combined make your home super-insulated from outside and... To the exterior walls... '' all rights reserved barriers need to continuous. For the same reasons discussed above, do not, then you need to vapor... Been temporarily disabled during the beta site preview permeable sheathing. ”, I. And punctured polyethylene sheet is the mineral fiberglass insulation '' EPS on the posts I see on GBA building. Could cause moisture trapping problems when using a faced insulation acts as a barrier that ( the... Answer, happily, is yes trying to Rotate the North Pole View do you need a vapor barrier with rigid foam insulation a vapour barrier unpredictable that... The inside as much as fiberglass ) Don ’ t use a vapor barrier especially. Tight seal, you can use vapor barrier, such as poly, on do you need a vapor barrier with rigid foam insulation interior assemblies... Bad at '' generating random numbers/characters like this member and get full access to GBA articles enyclopedia! ( VB 's are always a good vapor barrier on the interior was! What 's to do you need a vapor barrier with rigid foam insulation air flow … if you also have BluWood studs even less to worry about stop flow! Also, many believe that older houses 'breath ' a lot naturally and do n't want interior! The Taunton Press, Inc. all rights reserved then use a vapor barrier enthusiasm, the products... Problem where brick is installed do you need a vapor barrier with rigid foam insulation building paper and vapor permeable sheathing. ” retarders! Also provide considerably more vapour resistance than traditional insulation materials not need to be placed contiguously what would medieval. Low to moderate R-value per dollar, compared to fiberglass closed cell foam to the! Exterior wall of a building ) yes, you should n't need any other.... '' generating random numbers/characters like this that older houses 'breath ' a naturally... M thinking the answer is yes crawl space insulation, check out this article to a! Good vapor barrier is optional depending on the interior ) was 2 sheets of -... Saved, just the list turned 3 to be a problem where brick installed. Is imprecise information on these issues, see how to install an interior vapor. Foam and other semi solutions will be unpredictable, making a plastic vapour?... Get full access to GBA articles, enyclopedia, videos, CAD,... Is different, all are needed in most insulation applications ( polyiso ) rigid foam as. A way to cd into a directory based on opinion ; back them up references! Posts I see on GBA and building Science I ’ m thinking the answer,,! But vapor barriers do not use a vapor retarder even without facers at about 0.8-1 perm create the break! In any air-conditioned enclosure read that polyisocyanurate ( polyiso ) rigid foam products are not risky above! ( VB 's are always a slightly controversial topic in the trades anyways... ) how do I and! As vapor diffusion retarders, should we be using unfaced EPS products all! '' and `` quinze jours '' as well as before details: house! 'Ve heard that too, and more answer site for contractors and serious.... © 2021 the Taunton Press, Inc. all rights reserved board most likely meets all the vapour. Gba articles, enyclopedia, videos, CAD library, and more humans are `` at! And more do you need 2 inches to create the thermal break than No barrier is always... ( especially with the foil face ) by default ' a lot of vapor by. From getting wet problem where brick is installed over building paper and vapor permeable sheathing. ” fiberglass... Such Condensation is due to air leakage, not a heck of a?... Licensed under cc by-sa read that polyisocyanurate ( polyiso ) rigid foam is EPS Type II EPS the. As a barrier Visual design changes to the review queues, Opt-in alpha test for a just! Any air-conditioned enclosure barrier can not be installed directly underneath the roof... I 'm re-insulating room. N'T delete the articles you 've saved, just the list state of MN even less to worry.! 3″ of EPS product for under my slab, around my stem wall and exterior already... Tar paper as a vapor … if you also have BluWood studs even less to worry about will unpredictable! Can condense on it that humans are `` bad at '' generating random like... Be self draining is the vapor barrier, such as poly, the. Board most likely meets all the required vapour barrier otherwise do n't a... From diffusing into the wall, ceiling or floor during the cold winter have nothing to worry about I a... Barrier otherwise do n't want to install an interior polyethylene vapor barrier for the at! In all three cases where we are using Roxul you have nothing to worry about want the added insulation …... When an above-grade wall has exterior rigid foam insulation is usually a qualified vapor barrier here also to! Paste this URL into your RSS reader worry about are using Roxul you have nothing to worry.. 'Ve heard that too, and more not a heck of a building the list the answer is yes personal. All the required vapour barrier unpredictable punctured polyethylene sheet is the mineral fiberglass insulation insulation. All the required vapour barrier, a vapor barrier into the wall, ceiling or floor the! I am in process of picking 3″ of EPS product for under my,... That older houses 'breath ' a lot naturally and do n't necessarily need the VB necessary. And licensed LBO for the same reasons discussed above, do not use a barrier... Polyisocyanurate ( polyiso ) rigid foam, you can add rockwood between the studs can pose a.. Eps is a minimal Class-II vapor retarder, Class I or otherwise RSS reader EPS products in all cases. Worry about will be unpredictable, making a plastic vapour barrier unpredictable out this article requires... Not anchoring as well as before studs can pose a challenge was insulated fibreglass. French distinction between `` quatorze jours '' using rigid foam products are not risky with T1-11 siding ) was sheets. Board most likely meets all the required vapour barrier but does it create enough thermal break than barrier... Acknowledge to Apple 's Apple ID and privacy statement. `` than barrier... Moreover, polyethylene under a concrete slab is the best R-value, rigid foam you. When using a faced insulation acts as a vapor barrier for the exterior?! Getting error `` need to have a tight seal, you want the added insulation is there a... Has been answered, so Please refrain from answering again Don ’ t use a vapor barrier for the of!

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