Insulating A Finished Attic With Knee Walls

Insulate across the top of flat attic.

Insulating a finished attic with knee walls.

Insulating the floor and kneewall requires more careful air sealing but is sometimes easier to insulate since you can use blown insulation. A job we finished last week dropped from 4060 to 2150 cfm50 just with knee wall air sealing we were able to get 8 of one wall that had no top plate. If only the living space will be insulated wrap the insulation around the room s walls and ceiling and then continue along the floor of the non living space. In finished attic rooms with or without dormer insulate 2a between the studs of knee walls 2b between the studs and rafters of exterior walls and roof 2c and ceilings with cold spaces above.

Blown insulation in the knee wall and top attics. Unlike traditional walls with two finished sides. Despite all the bad publicity reflective insulation is getting lately i like to use it quite a bit on knee walls. 2d extend insulation into joist space to reduce air flows.

How to insulate knee walls. Knee walls are half walls built into areas where a full sized wall will not fit such as finished attic crawlspaces. 1a attic access door. If you want the attic to be outside then using foamboard on the attic side of the knee wall is a good idea.

1000 2000 cfm50 reductions are fairly common with this method. In these designs take out attic floor insulation only below the finished space from knee wall to knee wall and insulate the knee walls themselves. We reduced the air leakage nearly 50 on this house in shaker heights without insulating the walls. In this case the area behind the knee wall will be uncomfortably hot or cold.

There are two basic ways to insulate a finished attic. Kneewalls short walls under sloped ceilings are common in story and a half homes and in bonus rooms above garages.