Is It Worth Spray Foam Insulating Your Roof Rafters

Rigid foam board installation in the case of a cathedral ceiling involves installing three different layers that are each 1 5 inches thick according to the.

Is it worth spray foam insulating your roof rafters.

Two material options called open and closed cell where closed cell is more dense greater r value and much more expensive. However rigid foam insulation must be covered with a fire rated material when used on the interior of a building. If you decided to use a rigid foam board to help insulate your cathedral ceiling you would install the board on top of the roof sheathing and underneath the plywood at the top of the roof. Similar to loose fill though this is a liquid that when applied becomes a durable layer of foam insulation.

Then cover the foam with drywall as required for fire safety. Moisture from the house picture this. Half inch drywall is usually sufficient but check with local building officials before installing. You can also add rigid foam insulation under the rafters which adds r value and eliminates thermal bridging through wood rafters.

Polyurethane or polystyrene spray foams can provide thorough coverage to roof rafters and attic walls in much less time than is needed for other materials. Consumers are often told by spray foam contractors to do the rafters. Unlike solid insulation products that require careful measurement cutting and fitting spray foam can cover even the most uneven surface instantly. You take a shower but forget to turn the bath fan on.

This is because the effects of thermal bridging are limited which also results in the elimination of melt lines on the roof surface in cold climates. If you re using the attic for living space then you need to insulate the rafters. Your indoor air quality may get worse. With spray foam unlike with loose fill or batts you must cover the soffit vents they aren t needed to keep the roof cool.

You may have odor problems. The biggest benefit of spray foam insulation is its air sealing quality so if air is infiltrating into a spray foam attic then the installers missed some spots and need to go back and make it right. If you re not do the attic floor. Foam blocks airflow needs no vapor barrier and has a higher r value per inch than loose fill or batts so you ll get more protection with less depth.

Encapsulating the rafter or top truss chord roof framing members with spray foam will improve the energy efficiency of the attic space. It can be fairly messy so benefits from having experienced crew do the installation.