PVC sheets and XPS panels make a durable, airtight insulated sheathing
One efficient way to gain living space is with a pier foundation, but with the floor exposed to the elements, what’s the best way to insulate it?
ONE way to insulate the floor is with site-built insulated panels made from PVC sheets, adhesive foam, and XPS insulation. It’s like an open-faced insulation sandwich.
While you wait for the adhesive to set up, make another, and another, and another.
When you’re ready to install them, apply adhesive where the floor joists will be and slide that sheet over to the work zone.
Install the insulating panels with adhesive foam and long screws
It’s a lot easier to install insulated panels if you remove the ground because then, there is plenty of headroom.
- Install the sheets with edges splitting the floor joists and notch around the posts.
- The edges of the notches can be sealed with canned foam.
- Seal the outer edge with flashing tape tucked under the building wrap.
Insulate the floor framing with spray foam
The floor framing can be insulated in many ways, but closed-cell spray foam is an excellent way to add air sealing and serious thermal performance to the assembly.
Glue the subfloor on top to give one more layer of air sealing, and you’re ready to put the walls and grass back where they belong.
Above and below the floor.
(This detail comes from OA Design + Build + Architecture and was featured in Building Resilience Season 4's Continuous Exterior Insulation episode)