How to Install Insulation in Scissor Trusses on a New House

A scissor truss is a building method for combining a cathedral ceiling with adequate roof insulation. In scissor truss construction, the angled main rafters that hold up the roof are augmented by secondary rafters that meet the eaves at the same point as the main rafters but point upward at a less acute angle, meeting in the middle below the main rafters. The result is a wedge-shaped gap between the upper and lower rafters that can be filled with insulation. Installing the insulation in a new house is fairly simple.

Things You'll Need

Ladder
Batt insulation
Staple gun with staples

Measuring tape
Utility knife

Instructions

- 1
  Press batt insulation between the scissor trusses beginning at the eaves and working your way upward toward the roof ridge. Insert the insulation between the trusses so that the paper facing is on the bottom. Staple the edges of the paper facing to the lower face of the trusses using a staple gun.
- 2
  Cut holes in the insulation with a utility knife to accommodate protruding vents and ducts. Make holes smaller than the objects protruding through the insulation so that the insulation fits tightly around the objects.
- 3
  Leave air space between the insulation and the underside of the roof sheathing, particularly near the eaves where the scissor trusses are closest to the roof. The air space between the top of the insulation and the underside of the roof sheathing is important to allow air circulation from the eaves up to the ridge vent.

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