# Wine cellar walls: can I glue drywall directly onto polyurethane insulation?



## joecaption (Nov 30, 2011)

Simple ansewer is no.


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## dave_in_gva (Mar 8, 2013)

Tx Joe, short and sweet although I'm curious why not - is it an adhesion problem.

Any thoughts on options for me that are fast and result in a thin covering for the walls here?

Dave


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## Nailbags (Feb 1, 2012)

so you want to glue on to foam board 45+ pounds of weight? think for a moment. glue is just a adhesive to lessen the amount of screws or nails you will use on the studs. your going to have to frame in 2x4 walls and place the sheetrock on those. if you do it the way you described you will have a fat mess on your hands.


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## dave_in_gva (Mar 8, 2013)

Thanks, but I don't see why the walls would come down.

The foam insulation is fine to be glued directly to the concrete and sealed. If I use an adhesive specifically formulated for the insulation and use that to adhere the drywall to the foam, why should anything come down?

Is your reasoning that there would be an adhesive failure, an expansion/contraction issue, what?


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## dave_in_gva (Mar 8, 2013)

Also just to add, there are no studs. I live in Switzerland and they don't do timber frame houses here. Places are built in concrete and the basement I am building is is reinforced concrete and cinder block.

I get the weight argument a bit, but firstly I would be going with thin panels here (1 cm or 1.25 cm), so although I am not sure offhand what the weight of each panel will be it's unlikely to be huge.

D


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## Nailbags (Feb 1, 2012)

you will have failure with the glue. you need to use wood walls yes it might be expensive to do. if you don't do it right the first time when are you going to have time to go back and do it right. Just remember a 4x8 sheet of drywall weighs 48 pounds or 105.6 kg glue alone will not work.


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## spaceman spif (Jul 28, 2009)

Go to a local hardware store and pick up a piece of thin drywall and feel the weight - then imagine the only thing holding it in place is glue. If this is for a wine cellar you're risking that drywall falling onto your wine bottles. That's an expensive, messy, and highly likely risk.


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## brockmiera (Oct 9, 2012)

I just had to remove some 2" XPS from a section of my basement which had been glued with PL300 foam board glue. I had made a 1'x1' grid when I stuck it to the wall. Lets just say it came down surprisingly easy. 

What about using some 1x3's on the flat in front of the foam board. Use some tapcon's to secure them to to thru the foam board and into the CMU walls. Then you can use standard dywall screws to attach your drywall.


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## dave_in_gva (Mar 8, 2013)

Alright, so going with the logic here let's say I go with 2cm furring and I end up screwing my drywall onto that.

I've got two places I can put it:



Attach furring directly onto CMU, then glue 7 cm foam, then drywall with 8.5 or 9 cm drywall screws.
Glue 7cm foam direct to CMU, attach 2 cm furring through foam into CMU, then screw drywall with 3 cm drywall screws.
Option 1 puts an airspace between CMU and the insulation which would be convenient for passing some wiring I will need to run. I could also fill in the voids between the furring for additional insulation value. Downside could be longer length of the drywall screws and greater (but not necessarily important) shear forces because of this.

Option 2 puts the airspace to the interior (wine cellar) side of my insulation. That may be a bit more of a hassle for wiring in some of the electrical boxes as I'd have to reroute them back a bit into the foam insulation. Drywall screw length would obviously be standard and no shear force increase on the drywall screw....although seems to me I cant escape increased shear force in the total system with either option as putting the furring on the interior side of the foamboards means the fastener holding the furring to the CMU is longer and ultimately all the weight is hanging off that.

What I don't like in either option is thermal bridging. I want to get the maximum insulation value in this space while eating up a minimum of the interior volume.

Other thoughts, suggestions welcome.

Dave


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## dftc (Nov 12, 2012)

For minimum use of space your best option is to attach the foam board directly to the concrete with glue and seal the seams. Then add thin furring strip on top of the foam with the strips secured to the concrete through the foam. This gives you a surface to securely attach your drywall and it helps hold your foam panels to the wall. 
I don't know if it is available where you live, but there is a foam board product that has channels pre-cut into it that could accept the furring strips and eliminate the air space between your foam and drywall if that is really a problem for you.

If you want to add electrical you would need to cut into the foam. This can be done with most wood cutting tools, or using special heat tools.


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## dave_in_gva (Mar 8, 2013)

Thanks, that's sensible and I've seen this construction method talked about before on the net.

One thing I've been wondering about - and call me crazy if you have to - but I've been wondering whether and why furring strips need to extend vertically or horizontally as far as they do.

When I see images of applied furring strips they are not even locking into a horizontal member across the top and bottom of a wall, they're just vertical strips starting somewhere close to the bottom of the panel and ending somewhere close to the top.

But if you are only using that piece of wood to a) help hold a light piece of foam that is already glued to the concrete substrate and b) provide 2 cm of penetration into wood for a drywall screw every 60 cm, why does the furring strip need to be a long strip? Why couldn't one use a drill saw and cut out, say 6 cm diameter discs from 2 cm thick plywood and use those to secure the foam and then serve as a base to attach the drywall?

I realize there's more work but I don't mind doing the work and I dont see any structural reason why a 1 x 3 has to be say 8 feet tall when it is only getting tapped into by a couple of drywall screws every 2 feet. Downsizing the furring strip to a furring disc would give me less thermal bridging and allow me to build out the insulation another 2 cm. In fact I could even go with 2 cm thicker foam panels and simply use a drill saw to bore out a 2 cm recess in the front of the panels on 60 cm centres, insert the plywood discs, glue the assembly to the concrete, drill out and drive a mechanical fastener to fasten the plywood discs to the CMU wall, then glue and screw my drywall directly onto the foam, screwing onto those 6 cm discs on 60 cm centres.

Is there something inherently wrong with this strategy?

Dave M


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## coupe (Nov 25, 2011)

why cant you use fluted cncrete nails driven through the drywall and foam into the block? we did it all the time. I can show you a nursing home in Lebonon PA U.S.A. thats been hanging that way since 1972.


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## spaceman spif (Jul 28, 2009)

coupe said:


> why cant you use fluted cncrete nails driven through the drywall and foam into the block? we did it all the time. I can show you a nursing home in Lebonon PA U.S.A. thats been hanging that way since 1972.


That's something I was curious about. When you pierce the foam like that, aren't you creating a path for the moisture to travel along the nail surface and into the wood?


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## coupe (Nov 25, 2011)

no wood through drywall through foam. straight into block wall, dimple nails in as in wood finish as usual. I'm no good at the metric system have to figure length of nails 3/4" into block


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