Insulating Roof With Rigid Foam And Fiberglass

Rigid foam also can be installed above the roof sheathing in tandem with air permeable insulation between the rafters.

Insulating roof with rigid foam and fiberglass.

There are at least two good reasons why this approach makes more sense than installing the insulation under the roof sheathing. Code specifies the minimum r value of the rigid foam layer. Rigid foam r value. The spray can be basically applied on top or bottom of the metal roofing surfaces.

To ensure that humid indoor air won t reach the cold rim joist the crack at the perimeter of each piece of foam and at any penetrations should be sealed with caulk or canned spray foam. Fiberglass insulation is less than half the price of rigid foam insulation when calculated by r value per square foot. However not all rigid foam insulation packs are created equal. Polyurethane spray foam metal roof insulation.

Affix rigid foam insulation to the attic side of the hatch or door. Insulated roof assemblies can be vented or unvented. Rigid foam insulation creates a solid barrier between the inside and outside of your house acting as an obstacle in the way of heat and cold transfer. Rigid foam insulation tends to have a low to moderate r value per dollar compared to fiberglass.

There are lots of different ways to insulate this type of roof but one of the best methods calls for the installation of rigid foam insulation above the roof sheathing. Add weatherstripping around the perimeter and a. For a less pricey approach you can install 2 in. In this case the rigid foam can be thinner than when it s used alone.

Rigid foam on roof sheathing with air permeable insulation between the rafters. A 1 1 2 inch thick sheet of rigid foam insulation has a r value of 7 5. There is also less waste with fiberglass insulation. Rigid foam boards used in ceiling insulation are often made of either cellulose fiber fiberglass polystyrene or polyurethanes.

Per square foot of r value rigid foam board insulation costs about twice as much as fiberglass. For example insulating a 10 square foot wall area to r 15 costs about 3 40 to 4 00 with fiberglass insulation while a comparable r value for rigid foam costs roughly 10. Compared to the fiberglass batts this insulation is much better. Financially speaking this spray is a great option especially when you need to renovate your roof after the application.

Most local building codes require that rigid foam boards made from polyurethane or polystyrene be covered with a 15 minute fire rated thermal covering if they are used on the inside of the house. Foamular extruded polystyrene xps rigid foam insulation offers foamular extruded polystyrene xps rigid foam insulation offers a comprehensive line of products choose the strength you need from 15 to 60 psi and exceptional moisture resistance. Of rigid foam and a layer of fiberglass insulation in warmer climates 2 in. Products provide superior insulating properties.

Most packs of rigid foam feature a higher r value per inch than cellulose fiberglass or cotton.