Dave has almost finished the 1.5″ polyiso layer on the ceiling. This is the insulation that we bought from Repurposed Materials. The extra insulation on the ceiling is to eliminate the thermal bridging in the wood rafters. The walls of the house have a 1″ foil faced polyiso sheathing so they already have a thermal break.
Dave has marked the ceiling with pieces of tape where he wants to go back with an open can of Great Stuff to fill in the gaps between the sheets.
Some of the ceiling is quite high so it was nice to have the scaffolding to work up there.
The kitchen and living room are covered but the kitchen area still needs the gaps filled.
The wiring chase is open for now, it will be insulated and covered after the electrician pulls wire for the whole house. We won’t be able to finish the wiring until the walls are up though. Since the living room furniture is behind the posts, this open area is a “solar hall” where the sun shines brightly on the floor, warming the house and storing heat for evening.
The master bedroom ceiling is finished now. The narrow area at the vertical radon pipe will be the bedroom wall and entry.
We are going to add the Majpell air barrier film and battens to hang the drywall from. I purchased the air sealing products from A and E Building Systems, our local dealer for many of the best energy efficient building products. In our Indiana passive solar we put 2″ of old fashioned white polystyrene “beadboard” on the ceiling and just bought long screws to attach the drywall.
The battens and the gap filling ideas came from a Fine Homebuilding forum. We used 1.5″ polyiso and Dave did cut the pieces to follow the rafters, that was easier for him.
“…hang full sheets of 2″ polyiso on the rafters, just like hanging drywall. Leave a 1/4″ to 3/8″ gap between the edges of the sheets as you hang them. The ends of the sheets do not have to fall on the rafters, they can land over a rafter bay. I hang them with nails with round cap plates. You only need 4 per full sheet. Another R-12.
Once hung, peek into the gaps to find the rafters. Use a sharpie marker and mark the face of the polyiso so you know where the rafters are. Now use canned foam to seal the gaps.
Use scrap wood, real furring strips, or rip a sheet of 3/4″ ply into 1-1/2″ to 2″ wide strips. These will be your furring strips. Run these horizontally across the ceiling. Using the sharpie marks as your guide, use 4-1/2″ screws to screw through the furring strip, through the foam, and into the edge of the rafter. The ends of the furring strips do not have to fall on the ends of the rafter. They can also land mid-span. But offset the ends of the furring strips from the ends of the sheets of polyiso. If the furring strips are bowed, set them so the ends of the strips touch the polyiso. When you screw down the center, it’ll pull the ends even tighter.
Hang drywall off the furring strips. The drywall plus air gap is worth a little over R-1.”
This is where I found out about capped nails which have worked great. I had to go to Amazon to get long enough nails to go through the foam and into the rafters. We used 2.5″ nails. We have not used the whole box and they were not very expensive.
WoodPro Fasteners PC212-2M Ring Shank 2000-Count 2-1/2-Inch Electro Galvanized Plastic Cap Nails
After all the gaps are filled, we will install the air barrier and the battens for the drywall nailing, then we can hang walls!