Is It Worth Spray Foam Insulating Your Roof Rafters

By encapsulating the attic and leaving the old insulation up there that filth is in your conditioned space.

Is it worth spray foam insulating your roof rafters.

Consumers are often told by spray foam contractors to do the rafters. Two material options called open and closed cell where closed cell is more dense greater r value and much more expensive. 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. Encapsulating the rafter or top truss chord roof framing members with spray foam will improve the energy efficiency of the attic space.

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. It can be fairly messy so benefits from having experienced crew do the installation. 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. You may have odor problems.

However rigid foam insulation must be covered with a fire rated material when used on the interior of a building. Moisture from the house picture this. 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. 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.

If you re not do the attic floor. Unlike solid insulation products that require careful measurement cutting and fitting spray foam can cover even the most uneven surface instantly. Then cover the foam with drywall as required for fire safety. Half inch drywall is usually sufficient but check with local building officials before installing.

It s important you spray foam attic rafters only if you need to. 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. If you re using the attic for living space then you need to insulate the rafters. With spray foam unlike with loose fill or batts you must cover the soffit vents they aren t needed to keep the roof cool.

Similar to loose fill though this is a liquid that when applied becomes a durable layer of foam insulation. You can also add rigid foam insulation under the rafters which adds r value and eliminates thermal bridging through wood rafters.