battens over slab
I am planing to build over slab-on-grade which features 2″ of XPS and 15 mil Stego, as well as the specified vertical and horizon wing insulation.
As this is a relatively dry slab I’m thinking of skipping the pressure treated. And instead using battens/sleepers made from dougfir 4×4’s ripped to the appropriate thickness 2-3″ as per the laser. Then laid down and fastened with ramsets over a foam gasket (seal seal). And finally spraying the whole assembly with boracare with moldcare including the underside of 3/4″ CDX before closing it up. See any problems here?
I’m also wondering if the 2″ of XPS under the slab in my zone 6 is insufficient. That I might change my design and include some insulation. It feels a bit improperly matched to my R-50 walls and R-70 roof. But, then again it seems be meet general recommendations for my climate.
Thanks!
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Replies
You might want to bump up the slab insulation to R-15 or so to match your walls and roof, but it's not critical. PT is only required when the slab is in direct contact with the ground without an impermeable moisture barrier. Your membrane and insulation count as impermeable, so PT sleepers are not required. The Boracare/moldcare is a reasonable mold and insect prevention tactic.
Thanks peter , and for your reply to my previous post. It’s helpful to get confirmation that there isn’t a moisture or other issue that I may have overlooked.
Do you think I’m overdoing it by putting a sill gasket under the battens ?