The walls come with R16 closed cell foam with a radiant foil face toward the inside. The is a 6″ cavity between the concrete studs that I add R15 batts with wire standoffs from the foil, just because it is so inexpensive and helps control convective loops in the voids. For the roof deck I use closed cell spray foam that glues the decking and trusses together. Extremely strong and air tight.

What is the R-value of these panels? Do you use them for the roof too?

Thomas: Au contraire, sir. That 0.5 ACH50 tells me you have quite the robust air control layer. And you have lots of insulation, I’m sure, as part of your thermal control layer. Then there’s your drainage plane, flashing, and the other components of your water control layer on the roof, walls, and foundation. (If you have exposed 5000 psi concrete and it’s waterproof, that would be part of your water control layer, too.) Since you’re in a mixed-humid climate, you don’t need much of anything for a vapor control layer.

Maybe. Maybe not. Gravity is a force acting between two masses, in this case, the earth and some smaller quantity of liquid water. The others are driven by thermal or mass diffusion. Gravity on earth is pretty much only in one direction unless we look at lunar tides, but I don’t find that to be a problem with building envelopes. Diffusion can be in any direction.

Roy, are you saying there’s not a gravitational potential difference?