Insulating Roof With Rigid Foam And Fiberglass

Polyurethane spray foam metal roof insulation.

Insulating roof with rigid foam and fiberglass.

Rigid foam insulation tends to have a low to moderate r value per dollar compared to fiberglass. Rigid foam also can be installed above the roof sheathing in tandem with air permeable insulation between the rafters. Affix rigid foam insulation to the attic side of the hatch or door. 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.

Rigid foam on roof sheathing with air permeable insulation between the rafters. 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. Rigid foam boards used in ceiling insulation are often made of either cellulose fiber fiberglass polystyrene or polyurethanes. The spray can be basically applied on top or bottom of the metal roofing surfaces.

Add weatherstripping around the perimeter and a. Code specifies the minimum r value of the rigid foam layer. Per square foot of r value rigid foam board insulation costs about twice as much as fiberglass. There is also less waste with fiberglass insulation.

There are at least two good reasons why this approach makes more sense than installing the insulation under the roof sheathing. 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. Fiberglass insulation is less than half the price of rigid foam insulation when calculated by r value per square foot. A 1 1 2 inch thick sheet of rigid foam insulation has a r value of 7 5.

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. Water is insulation s enemy. It creates a breeding ground for mold and mildew and ruins the air trapping pockets that block heat flow. 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.

Compared to the fiberglass batts this insulation is much better. In this case the rigid foam can be thinner than when it s used alone. 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. For a less pricey approach you can install 2 in.

Insulated roof assemblies can be vented or unvented. Of foam may be enough. However not all rigid foam insulation packs are created equal. Financially speaking this spray is a great option especially when you need to renovate your roof after the application.

Of rigid foam and a layer of fiberglass insulation in warmer climates 2 in.