Is foamboard and stucco to the ground in a pier and beam house a termite risk?
SUMMARY: I’m contemplating installing foamboard + stucco over existing wood siding, running it all the way to the ground on my pier & beam house, but worry whether this could invite termites.
DETAILS: I want to insulate & encapsulate the area under my pier & beam house, but there’s not enough space under the house to work, and the existing stucco walls aren’t smooth for attaching foamboard even if I could get under there. At the same time, the exterior paint is peeling and likely contains lead, and repainting every X years is expensive and wastes paint if there’s an alternative. So, my idea is to annihilate two birds with one rock and to install foamboard and stucco like so:
(1) Demo the existing, damaged stucco skirting
(2) Install 1/2″ polyiso over the existing lap wood siding, but not over the old skirt area.
(3) Install 2″ XPS at the old skirt area, set in a channel dug 2″ into the ground, with its outside face being in a place with the 1/2″ polyiso on the walls.
(4) Air-seal the top of the polyiso with canned spray foam, and all other seams with housewrap tape.
(5) Install 1×3″ vertical fir strips to the foamboard, but ending 8″ above the ground, so ground-based termites can’t easily sense the wood.
(6) Install metal lathe and stucco.
However, I remember reading that running foamboard to the ground can invite termites somehow. I’m in Austin, TX, climate zone 2, which is a bit humid, but my reading of the local code is that there’s no ban on foamboard to the ground. I installed gutters and am putting in a French drain on the high side of the house to try to keep the soil around the house as dry as possible.
Is my plan sound, or does it suffer from inviting termites, or maybe some other problem?
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