Fiberglass Insulation Roof Rafters

The friction of the fiberglass insulation material against the rafters baffles and plywood or wood slats is.

Fiberglass insulation roof rafters.

Vented attics have insulation installed underneath the roof deck in direct contact with the decking. Air sealing hot roofs is critical. 7 staple sheets of 6 mil plastic over unfaced insulation to create a vapor barrier. Hot roofs are insulated above the rafters.

Unfaced batting insulation depends on a friction fit to keep it place. Unfaced insulation has no tabs and stays in place with friction between the fiberglass and the 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 can compress and lose r value and it s also unable to stop air from leaking out of or into your house.

R 30c and r 38c are available in both kraft faced and unfaced. The rafters in cathedral ceilings are usually made of 2x10 ft. 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.