View Full Version : Attaching sheetrock to foam board.

01-27-2004, 08:21 AM
I am going to use 1" rigid foam board with a reflective side facing my living space and I was wondering about attaching sheetrock.
I am using the board to reduce heat transfer through the studs and because I have infloor radiant heat.
Can I use the glue method to attach the sheetrock to the foam board?
The reason i ask is I didnt know you could even glue sheetrock untill I joined this web site.
I think it might be easyer and give me more of an even intallation.

01-27-2004, 04:37 PM
You cannot glue rock to foamboard. What you need to do is install "Z Channel" - it's a channel that the foamboard fits into and then you attach the rock to the Z channel with fine threaded drywall screws. The Z Channel comes in different depths and matches the depth of the foamboard.

01-27-2004, 09:25 PM
Steve, why can't Brad just use longer screws to find the studs behind the foamboard? What purpose does the Z-channel serve?

01-28-2004, 06:51 AM

Without the Z channel, the rock may not be attached to a firm surface; that is, the foamboard may give a little causing pops. The Z channel is made only for foamboard so the foamboard can fit into it and then the rock attached to it.

Mike Rooney
01-28-2004, 09:38 AM
You need an air space between the drywall and the foil. Hat channel or furring strips.

01-29-2004, 07:09 AM

Why the air space? Never heard of this although the Z Channel does offer little airspace.

Mike Rooney
01-29-2004, 10:51 AM
I saw this subject so long ago, I can't possibly remember where. I tend to remember concepts but not references. It has to do with the foil being able to reflect heat back into the room.

01-29-2004, 12:03 PM
I got a response from a JLHC forum from a guy whom did his whole house,walls and ceiling,in foam board because I was asking about insulation.
He said he went back years later and opened a wall to check for mositure and found none.He was real happy about his installation.
He also said that sealing the seams with tape is what gave him to tight house.
I am sure he didnt use Z channels.
If it is proper technique to use z channels I think that is what I want to do.
Can you tell me where to look on the internet for the z channels that is use with the foam board?
And/or some somewhere I can go to get more info. on this method.
I didnt actually know that you could use foam board at all on the interior side of a house till I got on this forum.
I cant use it on the exterior because I am using Hardy Plank and I dont think I could attach it as well as I would like.
I am a home owner doing my own house remodel (>1400 sq ft addition).

Thanks Brad

01-29-2004, 04:24 PM

I assumed that Brad was going to use the non-foil backed foamboard which is called rigid insulation.


I'm sure there is info on www.usg.com on Z Channels..but your local drywall distributor has it for sure. If you can't find it on the site..your drywall supplier has info on it. I just put up about 1,800 sq. ft. of it on an exterior walls in a sandwich shop.

01-29-2004, 09:06 PM
Can you clear something up for me?
I went to Home Depot and looked at their foam boards.
The pink and blue board is ridgid.(non tech.term by me)
The foil back board is somewhat yellow but it appears to be as ridgid as the other 2.
Are they not the same basic product?

01-30-2004, 05:16 PM
The foilback is a vapor barrier and used mainly on the outside of walls or on inside exterior walls. Since yours is on an interior wall, the pink one is fine but don't get the one with the tongue & groove.

01-31-2004, 08:06 PM
What I have done in my own home was insulated wall cavity with fiberglass insulation and then hung 2 inch foil back rigid on top of the studs.Then used wood strapping(1"x3") over foil,screwed long screws to framing,glued drywall over strapping,worked exellent.

02-01-2004, 08:04 PM
I couldn't find the Z-channel on USG's website, so if anyone knows where to get more info about it, please post.

02-02-2004, 07:19 PM
Three companies that manufacture it are:
website www.Dietrichindustries.com
website www.Daleincor.com
and you will have to do a seacch for Unimast Inc.
Hope this helps

02-04-2004, 07:08 PM
I think Dietrich bought Unimast. If you look at the page below, you'll see that Dietrich recommends their Z-channel for foam installations over masonry walls. But I guess you could use it over studs too.


Myron Ferguson
02-09-2004, 10:04 PM
Are you talking about resilant channel like RC1 and RC2 which I like to use as firing over wood framing. I use wood furing over the rigid insulation. I have attached the drywall directly over the rigid insulation and used adhesive along with screws and it stayed up nice and solid. I wouldn't attach it to anyting over one inch thick. The only problem I had was with the insulation expanding a little and creating a dimple at each fastener. So I would recomend using wood furing for best results.

Mike Chrest
03-04-2004, 08:01 AM
Myron & Drywaller,

Would you run the furing verticle or horizontal? Would RC1 work? I think using metal channel between the sheets of foam would defeat the purpose (thermal break) of the extra foam insulation.