Fiberglass Insulation Roof Rafters

Use your straightedge to compress the insulation before cutting and use a very sharp utility knife to assure a good straight cut across the fiberglass batt.

Fiberglass insulation roof rafters. R 30c and r 38c are available in both kraft faced and unfaced. Unfaced batting insulation depends on a friction fit to keep it place. Hot roofs are insulated above the rafters. Unfaced insulation has no tabs and stays in place with friction between the fiberglass and the rafters.

7 staple sheets of 6 mil plastic over unfaced insulation to create a vapor barrier. The rafters in cathedral ceilings are usually made of 2x10 ft. And owens corning ecotouch high density insulation products are designed specifically for these rafters. Attach insulation staple it to the rafters or scabbed on boards with a staple gun so that the paper backing is toward the interior of the room to act as a vapor barrier.

Because the insulation is so close to the roof and you want to avoid unwanted moisture buildup these roofs will need to be completely sealed off. Vented attics have insulation installed underneath the roof deck in direct contact with the decking. Air sealing hot roofs is critical.