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Edward Brassington Posted: Jul 20, 2008 10:07 PM	SPF on stone foundation I met with a client on Friday who is also a home inspector. This gentleman is very knowledgeable on building science, he also teaches at a local college. He is interested in having three inches of closed cell spray foam applied to his old stone foundation walls in the basement. He was telling me that there is a concern about spraying the ring joist that is embedded in the old concrete. The concern is that moisture moving from outside to inside through the old masonry wall, will become trapped when it meets the foam. The moisture then may travel upwards inside the wall causing moisture issues in the framing above and possible blistering of paint on the wooden siding. Normally, I would spray from the concrete floor to the underside of the floor above. We were playing with the idea of leaving the top two or three inches exposed to allow the moisture to escape. The ring joist in this house is actually a 12x12 beam. The home is located in Southern Ontario about 90 minutes North of Toronto. I appreciate your ideas on this.
mason Posted: Jul 21, 2008 07:56 AM	It is common to think of closed cell foam as a vapor barrier, but in reality it is a moisture vapor inhibitor. Water vapor can pass through the foam in a slow but controlled manner. If you are concerned about bulk water dripping into the foam, you could install a polyurethane sealant first to the suspect area and then spray the foam., Remember that ccSPF is used as a roofing system and is water resistant. (not waterproof). If there are high water tables in the area, there may be sufficient hydrostatic pressure to have water go into the foam. If the water tables are not high, there should not be sufficient hydrostatic pressure to saturate the foam. Hope this helps.

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Edward Brassington

Posted: Jul 20, 2008 10:07 PM

SPF on stone foundation

I met with a client on Friday who is also a home inspector. This gentleman is very knowledgeable on building science, he also teaches at a local college. He is interested in having three inches of closed cell spray foam applied to his old stone foundation walls in the basement.

He was telling me that there is a concern about spraying the ring joist that is embedded in the old concrete. The concern is that moisture moving from outside to inside through the old masonry wall, will become trapped when it meets the foam. The moisture then may travel upwards inside the wall causing moisture issues in the framing above and possible blistering of paint on the wooden siding.

Normally, I would spray from the concrete floor to the underside of the floor above. We were playing with the idea of leaving the top two or three inches exposed to allow the moisture to escape. The ring joist in this house is actually a 12x12 beam. The home is located in Southern Ontario about 90 minutes North of Toronto.

I appreciate your ideas on this.

mason

Posted: Jul 21, 2008 07:56 AM

It is common to think of closed cell foam as a vapor barrier, but in reality it is a moisture vapor inhibitor. Water vapor can pass through the foam in a slow but controlled manner.

If you are concerned about bulk water dripping into the foam, you could install a polyurethane sealant first to the suspect area and then spray the foam.,

Remember that ccSPF is used as a roofing system and is water resistant. (not waterproof). If there are high water tables in the area, there may be sufficient hydrostatic pressure to have water go into the foam. If the water tables are not high, there should not be sufficient hydrostatic pressure to saturate the foam.

Hope this helps.

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