# Product inquiry- insulating membrane over stone wall



## Easy Livin’ 3000 (Oct 16, 2017)

Looking for the best product for a very specific application. I'm tearing down the plaster and lath over furring strips to get back to the original rubble stone walls in the old farmhouse. I'll remove the lose plaster that was applied to the stone wall, and clean up any loose pointing.

Before I apply metal lath and replaster over the rubble stone, I'd like to add a barrier for both a little insulation and moisture barrier. I don't want this layer to add more than one inch of thickness to the walls. The walls are very irregular, so sheets of polyiso are out. Needs to be sprayable or perhaps even applied by roller or brush.

The reason I'm posting on this forum rather than the diy or green room is because the room that I'm starting with is the one containing the stove, and my main goal is to keep this rubble stone wall from being an enormous heat sink.


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## begreen (Oct 16, 2017)

Would it be possible to fir out the wall and fill in the spaces with 1" foamboard?

These articles might be helpful. There are many on the internet. 
https://www.engineshed.org/building-advice/common-problems/how-to-insulate-stone-walls/

https://www.homebuilding.co.uk/how-to-insulate-solid-stone-wall-homes/

http://www.greenhomebuilding.com/QandA/stone/thermal.htm


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## WoodyIsGoody (Oct 16, 2017)

There is a paint-on product I looked into a few years back that reflected IR radiation, like that from a stove. I believe it had millions of miniature, hollow glass spheres in it. Ceramic.


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## Circus (Oct 16, 2017)

Guessing insulating the exterior is out of the question. Years ago I repointed a field stone wall by throwing softball size balls of mortar at it and using a flexing trowel. Looked great.  If that wall was insulated it would make a good thermal mass reducing temp swings and burning frequency. Just an idea.


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## georgepds (Oct 17, 2017)

spray on close cell foam ( a vapor barrier as well as an insulator) comes to mind


http://www.greenbuildingadvisor.com/green-basics/spray-foam-insulation-open-and-closed-cell

http://www.greenbuildingadvisor.com...rability/37888/half-insulating-stone-basement


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## Easy Livin’ 3000 (Oct 17, 2017)

begreen said:


> Would it be possible to fir out the wall and fill in the spaces with 1" foamboard?
> 
> These articles might be helpful. There are many on the internet.
> https://www.engineshed.org/building-advice/common-problems/how-to-insulate-stone-walls/
> ...


This is what I pretty much have, minus the insulation.  The firring strips are already there, would just need to add the polyiso sheets and then cover with sheetrock.

I might end up doing this, but I'm hoping to regain some space, even it just a couple of inches on each side.


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## Easy Livin’ 3000 (Oct 17, 2017)

georgepds said:


> spray on close cell foam ( a vapor barrier as well as an insulator) comes to mind
> 
> 
> http://www.greenbuildingadvisor.com/green-basics/spray-foam-insulation-open-and-closed-cell
> ...


A thin layer of closed cell foam is probably what I'll end up with. Will require a quick light hand and a deft touch to keep it somewhat even.


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## Seasoned Oak (Oct 29, 2017)

Ill be doing foam board, and then green moisture resistant drywall over that, on the cold exposed wall in a basement im working on. Not sure exactly what ill do on the walls that are underground .They carry a little more moisture. possibly cement board with a space to drain at the bottom.  Not as worried about insulation here  as these walls dont get that cold.  May do some anyway.


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## Easy Livin’ 3000 (Oct 29, 2017)

Seasoned Oak said:


> Ill be doing foam board, and then green moisture resistant drywall over that, on the cold exposed wall in a basement im working on. Not sure exactly what ill do on the walls that are underground .They carry a little more moisture. possibly cement board with a space to drain at the bottom.  Not as worried about insulation here  as these walls dont get that cold.  May do some anyway.


Good luck with that project. Dad pulled the paneling down in their basement and put foam board between the cinder block wall, then replaced the paneling. Their stove was in the basement, and after that, the basement was super toasty, and the whole half of the house that was over the basement was warm and comfy.


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## peakbagger (Nov 2, 2017)

I recommend going with closed cell spray on so there is good vapor barrier and no gaps. If you leave gaps using a sheet product you could get mold build up in those gaps. Ideally you need enough insulation that at its coldest the interior side of the sprayed foam never gets near freezing as thats where condensate can start to form which is also possible mold point. 

Note I am assuming that the wall doesnt have an leak from the outside. Closed cell foam will stop condensation but if there is water coming in from the outside at any point it will find its way in. Contrary to the ads on TV, there isnt any easy to apply product that will stop leaks from the inside if there is water pressure on the outside. The leak needs to be fixed


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## Seasoned Oak (Nov 2, 2017)

peakbagger said:


> I recommend going with closed cell spray on so there is good vapor barrier and no gaps. If you leave gaps using a sheet product you could get mold build up in those gaps. water pressure on the outside. The leak needs to be fixed


I leave a gap using sheet foam that i fill with spray can foam. The whole wall spray on foam is just way too expensive around here, not practical at these prices. Perhaps eventually a small batch system will become relatively affordable for the general public. I agree ,you cant really stop water from the inside. The most you can hope for is to redirect it down ward and drain it after you have exhausted all efforts to stop it from the outside.


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## peakbagger (Nov 2, 2017)

I bit the bullet at one point and bought a two part kit and did my own spray job. Its a bit of crime how much stuff I ended up throwing away at the end of it. It got buried in insulation so I didnt have to worry about looks.


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## Seasoned Oak (Nov 2, 2017)

peakbagger said:


> I bit the bullet at one point and bought a two part kit and did my own spray job. Its a bit of crime how much stuff I ended up throwing away at the end of it. It got buried in insulation so I didnt have to worry about looks.


What did you have to put out for the kit?


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## peakbagger (Nov 2, 2017)

Its been a few years but around $300 for kit that covered a roughly 20' long by 8'  wall about 1.5 inches thick. Shipping added a bit as it has some hazard classification due to the pressurized cans. I have heard that there is local firm that sells the kits but havent located it. The smaller the kit the higher the cost for the product, double the cost gets 3 times more product. 

I had some foaming done by the local utility as part of an energy upgrade and some has failed several years after the work was done (some popped off and some shrank). There is enough that I am considering buying a kit compared to several cases of the spray can stuff as it goes on lot neater and quicker.


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## Easy Livin’ 3000 (Nov 2, 2017)

peakbagger said:


> Its been a few years but around $300 for kit that covered a roughly 20' long by 8'  wall about 1.5 inches thick. Shipping added a bit as it has some hazard classification due to the pressurized cans. I have heard that there is local firm that sells the kits but havent located it. The smaller the kit the higher the cost for the product, double the cost gets 3 times more product.
> 
> I had some foaming done by the local utility as part of an energy upgrade and some has failed several years after the work was done (some popped off and some shrank). There is enough that I am considering buying a kit compared to several cases of the spray can stuff as it goes on lot neater and quicker.


They sell a $300 kit at the local Home Despot. I might try it.  The end wall with the stove and a small window is 10' long, 6'6" tall.  I'd like to cover about 10' of the two side walls as well, and both have doors that are just shy of 3'. So, about 24' total. Since it is only 6'6" tall, one kit might do the whole job.


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## Seasoned Oak (Nov 2, 2017)

Got some 4 inch 4x8 Ft  foam boards for just about nothing recently, so ill probably use that. Only expense will be the perimeter foam from a spray can.


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## Easy Livin’ 3000 (Nov 2, 2017)

Seasoned Oak said:


> Got some 4 inch 4x8 Ft  foam boards for just about nothing recently, so ill probably use that. Only expense will be the perimeter foam from a spray can.


That's a fantastic find, those foam sheets are pricey, especially 4" thick ones. How'd you come across those?


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## georgepds (Nov 3, 2017)

If you are worried about seepage.. leave a channel between the foam sheets and stone wall, maybe using PT slats,then dig a drainage channel to a sump hole... 

This all may be more than you want to do


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## Seasoned Oak (Nov 3, 2017)

ED 3000 said:


> That's a fantastic find, those foam sheets are pricey, especially 4" thick ones. How'd you come across those?


Some company near here that Mfg them ,they get messed up orders. They actually want to dump trailer loads at a time. We got a few truck and dump trailer loads. Yea i think they are like $40 or $50 a sheet otherwise.


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## Seasoned Oak (Nov 3, 2017)

georgepds said:


> If you are worried about seepage.. leave a channel between the foam sheets and stone wall, maybe using PT slats,then dig a drainage channel to a sump hole...
> 
> This all may be more than you want to do


No seepage just damp wall ,sealed up from outside as best as could. 
There is all kinds of room as the stone wall is just randomly laid boulders with some flimsy morter mix that mostly doesnt stay in between em.  I may put a layer of cement board on the back of the wall facing the stone and the foam on the dry side. And elevate the wall with a half inch gap at the bottom to let out any potential water accumulation.


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## georgepds (Nov 3, 2017)

Seasoned Oak said:


> No seepage just damp wall ,sealed up from outside as best as could.
> There is all kinds of room as the stone wall is just randomly laid boulders with some flimsy morter mix that mostly doesnt stay in between em.  I may put a layer of cement board on the back of the wall facing the stone and the foam on the dry side. And elevate the wall with a half inch gap at the bottom to let out any potential water accumulation.




Sounds like a good idea... stone walls always seem damp to me.. providing a safety water channel is wise


Downside is heat loss through air leaks


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## Seasoned Oak (Nov 4, 2017)

georgepds said:


> Downside is heat loss through air leaks


This basement will only be heated occasionally ,so actually the only heat most of the time will be from ground heat about 45 degree floor temp.  underground wall will help with ground heat and above ground walls will be insulated and air tight. should stay about 40 to 50 with no heat.


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