Although kneewalls can help turn attics into living space they often present insulation challenges.
Foam board attic knee wall.
Air sealing and insulating the knee wall can make the attic space warmer more efficient and more comfortable.
Rigid air barrier material could include rigid foam insulation drywall plywood or osb among others.
Learn the best way to insulate a knee wall in.
Kneewalls short walls under sloped ceilings are common in story and a half homes and in bonus rooms above garages.
Then either fiberglass batts secured in place or netted cellulose is used to fill the rafter cavities.
I ve also seen attic kneewalls sheathed with non rigid materials mainly housewrap.
Most builders install fiberglass batts between the studs and some type of blown insulation between the floor joists.
Step 3 place caulking and furring strips.
The other is spraying at least 2 of closed cell spray foam directly onto the roof deck encapsulating the rafters.
In this video michael shows how to use spray foam fiberglass and foam board insulation to properly air seal a knee wall in an attic.
As you are improving your attic insulation you may have wondered what is the best way to insulate a knee wall.
Watch as he shows step by step instructions.
Install a continuous air barrier on the exterior side of the attic knee wall framing with a rigid air barrier or other supporting material to prevent the knee wall cavity insulation from sagging and to create a continuous thermal barrier.
The best way to provide that sheathing is to use a rigid material.
Watch as he shows step by step from measuring and cutting.
I ve seen osb oriented strand board the flaky plywood foamboard and structural or non structural cardboard sheathing materials like thermo ply.
This is not very easy in most of the older houses we work on because the hatches and attics are too small to get rigid foam board through.
Foam insulation boards can be attached to concrete walls as well and in such a case care should be taken not to chip the cement.
How to insulate a knee wall and air seal attic.
Step 2 install insulation boards.
When installing foam insulation boards in the attic make sure you start from one corner and work your way around the room.