How to Insulate Rafters With a Knee Wall

Properly insulating your ceiling saves on the cost of heating and cooling your home. If you’re finishing out at attic room or a loft, the room will likely have a knee wall, which is a short partition wall near the bottom of a sloped ceiling. Knee walls block the small triangular gable ends at the edges of rooms with vaulted rafters. You will insulate them at the same time you insulate the rest of the rafters before hanging drywall.

Roll insulation batting (un-faced)
4-foot insulation batts (paper faced)
Measuring tape
Utility knife
Staple gun

Instructions

- 1
  Measure the ceiling joist space behind the knee wall in the triangular floor areas. This area will be concealed by drywall eventually, and if you’re converting an existing attic space, it may already be insulated. If not, cut un-faced insulation batting to fit snugly in each joist space, and tuck it between the joists, but do not compress the batts. Fill every joist space in the same manner.
- 2
  Insert the bottom of a 4-foot paper-faced insulation batt into the bottom of a framed knee-wall space. The paper side should face the interior of the room.
- 3
  Unfold the paper attachment strips to fit on the adjacent knee wall studs and staple them in place, using about one staple every 12 inches or so.
- 4
  Work the insulation bat upward into the slanted rafter space at the top of the knee wall. Knee walls are different heights, but at the top where the framing studs line up with the rafters the stud spaces should also line up. Staple the paper strips to the vaulted rafters as you did to the knee wall studs.
- 5
  Continue adding insulation batts, working your way upward and cutting around roof vents with a utility knife, if needed. Cut batts to fit around outlets and vents.

Returning a Lowered Ceiling to Original Height

How to Estimate the Square Feet of a Cross Grid Suspension Ceiling

Ceilings