Polyurethane spray foam insulation for stone foundation

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Posted by: from Montreal
10/12/2011 at 6:51:02 PM

I have a house that is more than 100 years old. There seems to be much debate about whether it is possible to insulate the stone/rubble foundation walls. Is it possible to use spray foam polyurethane insulation in this circumstance without destablizing the foundation because of freezing of moisture in the foundation? I have seen some advise that it is possible to insulate just part of the wall to avoid foundation problems.

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Date/Time10/22/2011 at 3:25:29 PM

Hi Catherine, it sounds like you have a tough situation. If you are dealing with building structure, you must ensure it is stabilised and secured before doing anything to cover it up and make it inaccessible. It sounds like you have concerns with your foundation and you should post your requirements in the projects section so you can get some experienced contractors to have a look. You may also want to consult engineers to ensure the best solution(s) possible.

If it turns out that your foundation is good and water proof, you can use spray foam insulation directly over it. It will actually add some strength. Any of the manufacturers should be able to give you guidance.

Good Luck!

Jim Kuzma

Kettleby Handyman Services

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Kevin in Carleton Place
Date/Time11/24/2011 at 11:08:36 AM

Wow good question.

I would argue that spray foaming the exterior would be safe but maybe impractical. I can only assume that you dont realy use the basememt for anything but mechanical. Would it be possible to just frame around the mechanical and insulate that, as well as the underside of the main floor?

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Catherine in Montreal
Date/Time11/24/2011 at 6:07:26 PM

The basement is used for storage and mechanical right now. Because of the level of dampness, storage is restricted to things that cannot be damaged too much by the moisture level. We would like to insulate to save energy and make the space more liveable.

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Mike in Sault Ste. Marie
Date/Time1/8/2012 at 7:20:02 PM

Polyurethane spray foam is in the vicinity of 25 plus years old and while we personally have been spraying for only four years we have never had a problem with moisture destroying the wall afterward. In point of fact two pound foam is structural and will tighten most stone and brickwork. I will on Monday next contact Lapolla in Toronto to confirm you need not worry and I will post the information.

We have many century homes with stonework basements/crawl spaces and it makes me believe we would have heard of problems by now. Spraying in Northern Ontario one would see any problems rather quickly. If your interior walls are in fact damp or wet they would need be dry prior to spray as foam will not stick to wet surfaces, nor plastic as it is recycled plastic pop bottles and won't adhere to plastic.

Two pound foam is quite hydrophobic and post spray moisture has no effects on the foam or it's quality and/or R factor. You can go to the Lapolla site where most if not all your questions should be answered, if not you can contact them and they will come to your rescue.

Mike Lamothe O/O

Energy Tech Foam Home

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Trish in Winnipeg
Date/Time8/16/2012 at 3:11:56 PM

This is more of an additional question but i also have a house close to 100 years of age and with tyndall stone foundation. The current insulation (batt type) tends to wick water in (condensing) and creates the fine powdery dust on the stone walls.

Is there a preparation that should be used on the stone after cleaning off the dust to make the stone walls waterproof so that there is no chance of water wicking in after the polyurethane spray is applied?

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