Drywall over foam board insulation

[clemsonfor]

Just pulled a few more tiles down. Not sure of the batt size but it has 1x4s run perpendicular to the joists and then the paneling nailed to that then the tiles stapled along with the 1x4s. Im telling you the people who had my house loved paneling. It literally was on every wall. I had to take it off the sheetrock? Also the paneling in some places is over paneling, and most of the paneling had wall paper on it, at least twice in most cases.

 

[Danno1]

But a serious question, say i did have a proper plastic vapor barrior behind the tiles against the studs/joists. Why would it hurt to put foam (with taped joints) over that. There would be 2 barriors, similar to a double layer of plastic? I guess the only thing is if moisture gets between the 2 it would never leave.

You don't want to do this. You only want one vapor barrier; for the reason you already stated. And rest assured, mpoisture will eventually find it's way in there.


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[clemsonfor]

You don't want to do this. You only want one vapor barrier; for the reason you already stated. And rest assured, mpoisture will eventually find it's way in there.


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OK i dont, have a vapor barrior. The closest thing is the paper backed glass insulation. It will eventually let moisture out right?

Say i was going to add a proper, taped plastic vapor barrior. I would have to remove the batt insulation and replace with an un-backed batt insulation right?

 

[Danno1]

OK i dont, have a vapor barrior. The closest thing is the paper backed glass insulation. It will eventually let moisture out right?

Well, it's called a vapor barrier. But I don't know what it's permeance is......

Say i was going to add a proper, taped plastic vapor barrior. I would have to remove the batt insulation and replace with an un-backed batt insulation right?

Yes, that is what's recommended.


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[ak9]

maybe you've checked it? .., but in my experience most of the 12" x12" & 8"x8" ceiling tiles of the date period you decribe were asbestos ! I would not tear any down . I would however put a sealing/ceiling layer over them tho.Furring out with a metal hat channel/ z channel which integrates the foam insulation would be the way to do this in mho.
ak9

 

[clemsonfor]

I have some in the older part of the house which i have my suspictions that there asbestos? These in this part as well as some other parts of my home are not asbestos, there the Armstrong brand that they still sell at lowes. I guess they have made them for 30-40 years? I had a water leak issue a while back and had to pull down about 1 box worth on the lower level to dry the wood out behind it and due to stains. I went to Lowes and purchased a new box to replace the old, there is zero difference in what was there and the stuff i bought. That said though there is a difference between these and the ones below them on the first level, but im thinking its just ones smooth and the other has that pattern in them that looks like the marbled black and white compostion books you bought in grade school (well kindof). The ones on the older part of the house are a total different kind and like i said i have my suspecions, im not planning on removing them, and we did paint over them to "seal" them as recomended on the net. If i ever decide to drywall them i will just go over them for that very reason.


Anyway i have bout come to the conclusion to leave um be and put up 1/2 drywall over whats there. Reason for the 1/2 and not 1/4 is the price. 1/2 4x8 is like $7.30 at lowes the 1/4 is like $12 for the same size??

I decided against the foam cause it will only give me R-3.5 for 3/4" foam. If i did tear the ceiling tiles and 1/8 paneling down my reasearch on the net gives those 2 items about a r-1.8 or so. By removing them and putting the foam im only gaining a R-1.5 or so over just putting drywall over what i got and now were splitting hairs. I will never notice even R-3 there on the ceiling i wouldnt think and for the posibility of screw pops etc i dont want the hassel plus the fact i would have to buy more expensive screws (longer) to do it.

But on the walls i dont have the tiles and i could still do it??? Na what am i thinking still the double vapor barrior effect would be in place. Im just gonna rock it all over and then put some r-30 batt in the attic where i can get over the room. I will probably pull the paneling out halfway up the wall to look at/run new electrical in the room first though. Replace the cut out to level it back up then drywall over the paneling on the walls.

 

[Jay4200]

A 2" foam thermal break placed under drywall for ceilings AND walls is standard fare for super-insulated construction. I don't know whether they use closed-cell (R10) or polyurethane (R13-14).

I put 1" of polyurethane (Celotex) foam above the sheetrock on a cathedral ceiling, below 2x10 rafters insulated with R30 high-density fiberglass under styrofoam vent channels. My roof is always the last roof with snow on it in the neighborhood every spring - remarkable for a cathedral ceiling. If I were to do it over again, however, I would put strapping over the foam, then put up the sheetrock.

JayC

 

[SPIKER]

I might go with the radiant barrier type insulation in place of the foam board. the foil bubble bubble foil type that will provide the vapor barrier on top of a dual radian barrier to reflect that summer heat and winter cool...

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