Fiberglass Insulation Roof Rafters

The rafters in cathedral ceilings are usually made of 2x10 ft.

Fiberglass insulation roof rafters.

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. Unfaced batting insulation depends on a friction fit to keep it place. Air sealing hot roofs is critical. 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. And owens corning ecotouch high density insulation products are designed specifically for these rafters. Vented attics have insulation installed underneath the roof deck in direct contact with the decking. The friction of the fiberglass insulation material against the rafters baffles and plywood or wood slats is.

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. R 30c and r 38c are available in both kraft faced and unfaced. 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.