Insulation in beam pockets in concrete foundation walls
jadziedzic
| Posted in Energy Efficiency and Durability on
I’ll soon be embarking on installation of interior continuous rigid foam (NGX 150 XPS 1-1/2″ CZ5) on my home’s concrete foundation walls. I’ve read a few concerns expressed online about using closed-cell spray foam around beams in pockets in the foundation, due to the potential of moisture accumulation around the beam leading to deterioration of the beam end (in this case triple 1-1/2″ LVLs).
Would using mineral wool insulation in this area lessen any potential concerns? It would be nice to close off those sources of cold. The pockets are above exterior grade level so water infiltration from the exterior is unlikely.
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Replies
Is there capillary break between the LVL and the foundation? If there is, I would not worry about it and insulate with rigid sealed in place with canned foam.
If you are missing a capillary break, your best bet is to air seal only and leave the beams uninsulated.
To clarify, it would be OK for me to air seal the "face" of the concrete around the beam pocket to the perimeter of the beam where it enters the pocket. Would I seal the foundation wall foam to the beam perimeter? (If I need some sort of gap I have some Intello Plus on hand that I use for that, seems like the vapor permeability would be a good thing. )
Thanks Akos. The LVLs are resting on shims of pressure-treated wood, and the rear of the LVL is spaced off the back of the pocket. Do the shims count as a capillary break?
jadziedzic,
The shims aren't a capillary break, but I guarantee you could jack the ends of the LVLs up the 1/16" you need to insert a piece of laminate under them without causing any damage.
Hi Malcom - Thanks for the suggestion. Logically I understand the suggestion, but the nervous side of me shudders at the thought of jacking up the LVL at the end ... I'll have to ponder that approach.
Jacking up a beam 1/16" vs. waiting for it to rot--seems like an easy decision to me.