8

I called USG,the maker of Durock cement board Next Gen, and they advised using no vapor barrier so that the wall cavity can breath and allow any moisture to evaporate. Their online instructions/diagrams show no use of a vapor barrier.


8

You should NOT place a vapor barrier BEHIND the backer board. Where, pray tell, would any such collected vapor/water go? Answer:There's nowhere proper for such moisture to egress. The current best practice is to place waterproofing OVER the backetboard and just UNDER the tile. Thin sheet membranes like Kerdi or NobleFlex are examples . Paint on ...


7

Yes vapor barriers are to prevent condensation inside of insulation, greatly reducing its efficiency. In your climate, if you use air conditioning and that space has insulated exterior walls, you will want a vapor barrier on the exterior side of the insulation to prevent outside humidity from condensing inside the cooler insulation. If your exterior walls ...


7

Ask yourself this: "If I install a vapor barrier, where is the water that it stops going to collect?" If you put a polyethylene vapor barrier behind a drywall-covered stud framed wall, then the answer is that water that condenses on the poly will fall onto the wood sill plate, growing mold and eventually rotting it out. Dedicated vapor barriers ...


6

I think you'll have to get one of these vapor barrier boxes, and fit it before installing your electrical box. Seal up where the cable penetrates, then install your electrical box. The other options would be to cut a larger hole and patch drywall, or seal it up from the back side (but that would require access to the other side of the wall/ceiling).


5

I'll answer the second question first: Where would I go looking for any such information for my location? Your city's building and code inspector's office. But note that because something is to code doesn't necessarily mean it has to be done that way--provided you can show why your way is better. Which leads to your first question: Does anyone know ...


4

You don't seal the vents, ventilation of the crawlspace is needed to prevent moisture buildup and rot. I had to take on the very same project. There are three objectives. Under house air can have mold in it, you shouldn't be breathing it, block all air exchange between the living space and the crawl space. Under house moisture levels must be brought down ...


4

It is a good idea to seal any apertures between the crawlspace and the main house. If you have to rely on caulk and spray foam you're probably in a situation where the house has some weird structural problems - that is, you should not have giant gaps between the crawlspace and the floor above in any normal construction regimen. It is not a good idea to ...


4

Nearly all of Virginia is considered to be in the "mixed-humid" zone. On an annual average, moisture migration is fairly evenly distributed (alternating toward the interior and toward the exterior). Moist air tends to migrate toward the cold side of a wall. The vapor retarder is installed correctly, in your crawl space, to discourage exterior humidity ...


4

Insulated slabs usually have vapor barrier underneath. Since you did a test and found no moisture, there should be no problem installing vinyl flooring on it.


3

Yep, the 120 year old houses do make life more interesting (and expensive and/or colder.) Use an air barrier that is NOT a vapor barrier. More commonly known as housewrap. Vapor moves through, but bulk air movement is reduced. For insulating inside the floor joists, either blown-in cellulose (which supposedly has very little issue with vapor, due to having ...


3

Rigid foam insulation is usually a qualified vapor barrier. However, an installation between the studs can pose a challenge. 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 facilitate vapor flow.


3

No, there's no need to install a vapor barrier between two conditioned spaces. The purpose of a vapor barrier is to prevent warm moist air from traveling through the insulation and condensing on the cooler side, which can easily happen in cold climates. With a conditioned space on both sides, you can allow any moisture in the air to pass through. There's ...


3

You can put a vapor/moisture barrier up over rigid foam. A lot of new construction in the far north has this as a default. The idea is that you frame right outside of that. In that framing you are allotting a cavity to which moisture can move and evaporate. Now if you are putting rockwool or other types of insulation in your framing then no you do not ...


3

The TL;DR -- vapor barriers belong on the outside only You should only place a vapor barrier on the exterior side of the exterior wall, allowing the assembly to dry back to the inside if water does get in past the tub surround. I would recommend paperless drywall over cement board for the tub surround, as well -- gypsum board of all types is vapor open (...


3

the plastic will trap moisture in your sheetrock and can cause black mold some areas require hazmat teams for black mold removal, Ran into this a few years ago and it was quite expensive for the home owner.


2

Moist air is condensing (barring any oughtright leaks) It is most likely due to air leakage from house to attic: Ceiling to attic is leaking moist air, condensing. Solution: air sealing of all penetrations (light fixtures, ducting, electrical, gaps in construction) Insufficient insulation, combined with air leakage allows condensation to occur. Vapor ...


2

Safest bet is to replace it of course - but in your case I wouldn't call it necessary. There's an easier way to replace the vapor barrier. Run the barrier over the trusses. Keep it flush to the drywall but run it up over the truss and down again. Of course, if your house is that old that it had vermiculite, I'm going to bet that you've got about 8 ...


2

There is more to it than vapour barrier. The rigid board most likely meets all the required vapour barrier but does it create enough thermal break? Warm air can still hit the foam board and if the board is cool enough warm air can condense on it. Most rigid board is R-5 per inch so you probably need 2 inches to create the thermal break necessary. On dow's ...


2

You should, so that any moisture that gets behind the cement board runs into the tub or shower instead of into your wall cavity (causing rot or mold/mildew). If you overlap the moisture barrier with the raised lip around the tub, any moisture has only one path to take due to gravity -- down the barrier and into the tub. I usually use thick-mil plastic ...


2

You have asked several questions at once so a little difficult to give you the answers you want. First, Hardy backer board is a newer, lighter, substitute for concrete board and usually used in bathrooms and under tile installations. I have never seen it used on exterior walls as a sheathing. Second, the huberZip system is from Advantec. I love Advantec ...


2

plastic behind cement board with waterproofing is essentially suspenders when you already have a belt. the waterproofing is also a vapor retarder so if the red guard or kerdi product is continuous, lapping corners and all, the plastic will be unnecessary. if you think of tile like exterior cladding, it would make sense to leave an open hole in the ...


2

Follow manufacturer's instructions first and foremost. Also in places with hot humid climate vapor barrier on the inside wall causes more trouble than it fixes. https://www.jameshardiepros.com/getattachment/98adb0c7-1bd1-49e7-a9d4-a8275d29ae4a/HardieBacker-Installation-Guide-English_Spanish-HB1710.pdf Note on page 4 "vapor barrier if local codes require." ...


2

You are correct. The field of building science is gradually moving away from friendliness toward vapor barriers in exterior walls, and you certainly should not put one in an interior wall or floor. Not a great idea. In addition, it would make more sense to use batt or spray foam insulation between the floor joists as opposed to cutting rigid foam to fit in ...


2

Most blue tarps are usually some kind of coated fiber construction and first, I would question how vapor impermeable it really is, and second I think it would not be nearly as resilient and repairable as poly. Once the tarp material starts to break down and/or tear, it seems to be impossible to repair in my experience. Admittedly, that has always been in ...


2

Provided you don't have knob-and-tube wiring, this one is easy. Remove the vinyl siding, cut holes through the EPS foam and the sheathing at the top of each stud bay, and inject dense-packed cellulose into the empty stud bays. Should be pretty cheap and help a ton. I wouldn't use retrofit-style non-expanding foam. It'll be more expensive, highly flammable, ...


2

Ideally, you would have used rigid insulation against the concrete. This would have worked as both your insulation and a vapor retarder (but not barrier). These days, vapor barriers are frowned upon in basements, as they ultimately lead to trapped moisture somewhere. The only exception is closed-cell spray foam. That acts as a vapor barrier and insulation, ...


2

Are you sure it was mold? It may have been mildew. In my experience, mildew can grow on nearly any surface as long as it stays moist...be it bare concrete or painted concrete. In this case, the moisture on this interior wall likely is not coming from outside the basement, but rather is moist air condensing on the cool concrete. Painting it won't stop that ...


2

Closed-cell foam insulation is a vapor barrier itself. If this closed-cell foam is continuous, then you shouldn't have any issues. If it is just in the cavities between wood studs, then the studs may act as thermal bridges which may result in condensation on the humid side if the studs get cold enough.


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