Insulating Roof With Rigid Foam And Fiberglass

Insulated roof assemblies can be vented or unvented.

Insulating roof with rigid foam and fiberglass.

Code specifies the minimum r value of the rigid foam layer. The spray can be basically applied on top or bottom of the metal roofing surfaces. In this case the rigid foam can be thinner than when it s used alone. For a less pricey approach you can install 2 in.

Polyurethane spray foam metal roof insulation. Most packs of rigid foam feature a higher r value per inch than cellulose fiberglass or cotton. Per square foot of r value rigid foam board insulation costs about twice as much as fiberglass. Affix rigid foam insulation to the attic side of the hatch or door.

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. Rigid foam r value. Rigid foam on roof sheathing with air permeable insulation between the rafters. Rigid foam insulation tends to have a low to moderate r value per dollar compared to fiberglass.

Fiberglass insulation is less than half the price of rigid foam insulation when calculated by r value per square foot. Of rigid foam and a layer of fiberglass insulation in warmer climates 2 in. Add weatherstripping around the perimeter and a. 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.

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. It creates a breeding ground for mold and mildew and ruins the air trapping pockets that block heat flow. 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. 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. There is also less waste with fiberglass insulation. Of foam may be enough. 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.

Water is insulation s enemy. However not all rigid foam insulation packs are created equal. 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. Rigid foam boards used in ceiling insulation are often made of either cellulose fiber fiberglass polystyrene or polyurethanes.

There are at least two good reasons why this approach makes more sense than installing the insulation under the roof sheathing.