Best approach to termite shield and sill plate air sealing
Please see the attached image. Zone 5, high desert, with termites.
I have a slab on grade with edge insulation and a parged coating. Above I’ll have a termite shield, then the framed wall.
Questions, your preferences –
1. Stainless or galvanized sheet metal for the shield?
2. Considering that the air barrier happens at the sheathing, with all joints taped, I need to seal the sill plate. There are 2 surfaces to consider, below and above the termite shield. What would be your preferred sealants for both those surfaces? Some choices, thin foam strips (I hear not very effective), generous beads of acoustical sealant, rubber gaskets, no sealant at all and rather caulk the joint between the sill and the concrete on the interior.
3. Do I need to tape the wall sheathing to the termite shield for air barrier if I’ve got a sealed sill?
4. Alternatively to Q.3 I could tape the bottom of the wall sheathing to the underside of the sill before the wall is lifted into position. This would cover the joint between the sheathing and the sill plate.
5. Does the sill plate need to be pressure treated if it is separated from the concrete by 2 layers of sealant and a termite shield?
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Replies
1. I guess I don't know why, but I've only ever seen copper (or something copper-like) used as termite shield.
2. Check this article out (more info in the PDF):
https://www.greenbuildingadvisor.com/article/air-sealed-mudsill-assembly
Martin's got a pretty dialed air-sealed mudsill assembly.
3. I would think not, if the sill is sealed well using the method in Martin's article above.
4. Seems like this could be finicky to actually pull off?
5. I was just asking myself this question yesterday, as it happens. Check out these two articles:
https://www.jlconline.com/how-to/framing/is-treated-wood-always-required-for-sills_o
https://www.greenbuildingadvisor.com/article/getting-mudsills-right#:~:text=Because%20mudsills%20are%20installed%20close,are%20generally%20pressure%2Dtreated%20lumber.
Short answer: if you've got enough clearance from grade and you have a capillary break you're probably okay, but there's no compelling reason not to use PT and it might save you hassle down the road from an inspector.