Almost done with a big reno of the entire main floor of my home. I have finally decided to put in an active cellar but I’m a bit concerned with how the vapor barrier may have been installed. I thought I would run it past the group and see what the feedback was.
This is on the main floor of my home and over my crawlspace. We blew out the side of my house to get a bit of extra room and bumped out the cellar space approx 2 feet. So the entire back wall is on an outside wall as is approx 1/3rd of the side walls, ceiling and floor. The rest is inside my home. The front of the cellar is double paned commercial glass with a heavy duty fully sealing door.
I was very specific with my contractor that the vapor barrier needed to go on the OUTSIDE of the room not the inside. We decided to use closed cell spray foam for this. Floor and ceiling are 2x10 and the walls are all 2x4. I will explain (from the outside in) what was used on the back wall and side walls in terms of construction.
vinyl siding → fabric house wrap → plywood – 2x4 studs → in all the stud cavities 3.5 inches of closed cell foam was sprayed and trimmed to fit -->plywood → cement board (which he sealed with red guard) → brick facade inside the cellar affixed with thinset motor
For ceiling he simply sprayed closed cell foam into all the cavities (a lot of foam as he filled the 10 inch cavities)… he then put a plastic vapour barrier in (no idea why as i didnt tell him to do this) and then installed the ceiling material which was just some old engineered hardwood I had that is the glue together floating style.
On the floor he went into the crawpsace and sprayed the entire cavity with closed cell sprayfoam right onto the underside of the subfloor. Then on top of that he put a schulter tiling membrane and we put the bricks on top of that.
My concerns center around a couple of items 1) is it ok to sandwich sprayfoam between two pieces of plywood? 2) he did not caulk/seal any of the areas of the walls/ceiling/floor where wood was butted up against other wood, he just sprayed the cavities 3) not sure why he put that plastic vapour barrier in the roof on the cold side of the cellar, it may be not overly important as there as in a bunch of lighting there so the vapour barrier has lots of holes in it, no way it is “air tight”. Also not sure why he used the red guard on the seems of the cement board other then he is probably used to doing that in bathroom applications.
sorry maybe I should add that I live in the pacific northwest in a fairly temperate climate and the exterior wall the wine cellar is on is on the north side of the house, it never sees the direct sun as its blocked by the second floor of my home.
I don’t see why there would be a problem with foam between 2 pieces of plywood - just like a SIP.
As for not caulking - I’m assuming you are meaning in areas like where the framing comes together (e.g. plate touches the subfloor). While that is a good practice I think you will be ok.
I also don’t see a problem with adding the red guard.
As for vapor barrier on interior ceiling each area has its own code. I am in Va so don’t know PNW.
Did you ask your contractor these questions?
Sounds like you are making a nice space with the brick finish.
I did ask him but I feel he is more of a GC and he has not done too many wine cellars. I find sometimes the reverse nature of the vapour barrier then what they are used to can cause them to think of it the wrong way.
My concern with the redgaurd is he is placing vapour barriers on top of each other and I worry that moisture could get trapped in there. Was just looking now and it appears he may have also put a plastic vapour barrier between the concrete board and ply on the inside. That would make 3 barriers all together (on the same side). But please feel free to let me know if I’m over thinking this, that would certainly make me feel better!
I don’t see a problem with sandwiching the spray foam with plywood.
It’s not clear to me what you mean by “where wood was butted up against other wood.”, but I assume here you’re talking about where studs meet sill plates, etc. If that’s the case, I think you’re ok. While having a positive airtight seal with caulk or spray foam would be better, I think you’ll probably be ok. The studs should be tight to the plates, and I the amount of air that can squeeze through the 3.5 inches of contact area will be minimal.
I wouldn’t worry about that plastic sheet at all. Yeah, it’s not “the way it’s supposed to be done”, but assuming it’s pressed up against the foam, it’s effectively just an extension of the foam vapor barrier.
Edit: To clarify, the real concern here would be if you had a porous layer sandwiched between two vapor barriers (such as spray foam, then fiberglass insulation, then a plastic vapor barrier), which risks trapping moisture and promoting mold growth. The case you describe (plastic sheeting pressed directly against spray foam) isn’t ideal, but with no moisture wicking/retaining material sandwiched between the vapor barriers, I think the risk is much less.
I’m not familiar with “red guard”, so I can’t comment on that.
Would you consider plywood on the cold side of the cellar to be a porous layer? As it is effectkybsandwiched between the spray foam and plastic sheeting then cement board that has been red gaurded, all on the cold side of the cellar… redgaurd is a sealing compound that is painted over joints in cement board to make a watertight seam. Usually used in bathroom applications.
Unfortunately, yes. Plywood is porous, and can definitely mold. That’s not to say that you will run into a mold problem. But I’d say that with plywood trapped between two vapor barriers it’s more likely than it would have been otherwise.
That is what I figured. Tough decision now is do I rip down all the brick and the entire inside of the cellar and start new which will be very destructive and expensive or do I proceed on and “see how it goes”… with all those layers I’m unsure of how I would even be able to determine there was a moisture problem prior to any major water damage…
An option I have is to drill small holes through the concrete board and poly barrier on the inside via the grout lines of the brick, I could do this quite easily as the brick isn’t grouted yet, every 3-6 inches. I guess the question is does that actually provide sufficient air flow between those sandwiched layers or is that a pointless exercise?
I wish I could tell you. I guess you could call a company that specializes in building cellars and ask them, but they would be self-interested to tell you to tear it out and hire them. It’s a tough call.
Isn’t closed cell foam (unlike open cell foam) also a vapor barrier? If so, is there a need for a vapor barrier on top of a vapor barrier? Or am I missing something (which is quite possible!)?
You’re correct it is a vapour barrier, so now I have multiple which is where the issue may be. This is not a case of “more is better”. You ideally want only one vapour barrier so you don’t create a moisture trap
Update: I spoke with my contractor and we have decided to make cuts down each corner of the room through the brick and through the cement board and red guard sealant. I confirmed that there is no plastic vapour barrier in the walls just the ceiling, which is good. The hope is that then there is no longer a second vapour barrier in the cold side of the cellar and should any moisture get in the wall the cooling unit will be able to draw that moisture out and there will be a bit of possible airflow between layers. I will then put brick motor over the cut lines which is pourus. I will monitor the ceiling for moisture (it is easy to pop out a light and stick my hand up there. If there is any moisture taking down the ceiling and removing the plastic barrier which is against the foam is relatively easy. If anyone has other suggestions I’m all ears.
