# Spray Foam in Walls & Moisture Question



## leeave96 (Jul 3, 2011)

I've got an old house and the walls have zero insulation in them. In as much as my house is a wooden structure (no brick), I have read some articles about using loose/blown-in insulation, however, as there is no vapor barrier to the interior or exterior walls and the insulation will trap moisture and eventually cause wood rot a the base of the walls where the moisture condensates at.

I'm interested in insulating my home's exterior walls and maybe spray foam might be the answer. My interior walls are lath and plaster and the outside walls are pine with 2 x 4 studs between. If I get a contractor to do a spray foam insulation into the walls, they would have to do it from the exterior.

A couple of questions:

1. Will the spray foam create a vapor barrier or would I encounter the same moisture problems as I would with loose blown-in insulation?

2. Any recommendations as to open vs closed cell foam?

Any other advice or recommendations would be greatly appreciated.

Thanks!!!!!!!
Bill


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## Windows on Wash (Aug 30, 2011)

Location and some pictures of the home are going to help tremendously to start with.

Are you planning on tearing off the exterior walls or just doing a drip foam?

If the exterior wall is being stripped, now is the time for rigid foam to be put up prior to re-cladding the exterior.

The answers to #1 and 2 depend on location and climate.


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## leeave96 (Jul 3, 2011)

Windows on Wash said:


> Location and some pictures of the home are going to help tremendously to start with.
> 
> Are you planning on tearing off the exterior walls or just doing a drip foam?
> 
> ...


Thanks for the reply!

I'm near Roanoke VA. The exterior walls will not be taken off. I know nothing about this foam, so take my comments/assumptions with that in mind - but...

I thought the foam would be sprayed-in via round holes - not unlike a loose fill insulation. The foam would expand to fill the cavity between the interior and exterior wall - creating the moisture barrier and insulation.

Thanks,
Bill


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## Windows on Wash (Aug 30, 2011)

Have you had any evidence of leaks previously?

You don't require a vapor barrier here in VA beyond what your plaster and lathe with paint on it provide. 

How are they drilling the holes? Are they removing siding to access the sheathing and is there any?

Cellulose (Borate only) is well suited for this application if installed by a capable installer.


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## leeave96 (Jul 3, 2011)

Windows on Wash said:


> Have you had any evidence of leaks previously?
> 
> You don't require a vapor barrier here in VA beyond what your plaster and lathe with paint on it provide.
> 
> ...


I don't think they remove sheathing - but drill holes, at least that's what I've seen at a distance driving around seeing what I think is insulation being installed into an exterior wall. But I don't know if those applications were blown insulation of foam.

Good info on the requirement for vapor barrier.

Thanks,
Bill


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