Is It Worth Spray Foam Insulating Your Roof Rafters

Encapsulating the rafter or top truss chord roof framing members with spray foam will improve the energy efficiency of the attic space.

Is it worth spray foam insulating your roof rafters.

If you re not do the attic floor. You may have odor problems. Half inch drywall is usually sufficient but check with local building officials before installing. Yeah you probably still breathed some of it but not as much as you will now with spray foam on the roof deck.

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. You take a shower but forget to turn the bath fan on. 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 using the attic for living space then you need to insulate the rafters.

Similar to loose fill though this is a liquid that when applied becomes a durable layer of foam insulation. It s important you spray foam attic rafters only if you need to. By encapsulating the attic and leaving the old insulation up there that filth is in your conditioned 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.

Two material options called open and closed cell where closed cell is more dense greater r value and much more expensive. Your indoor air quality may get worse. You can also add rigid foam insulation under the rafters which adds r value and eliminates thermal bridging through wood rafters. 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.

Moisture from the house picture this. Consumers are often told by spray foam contractors to do the rafters. It can be fairly messy so benefits from having experienced crew do the installation. With spray foam unlike with loose fill or batts you must cover the soffit vents they aren t needed to keep the roof cool.

However rigid foam insulation must be covered with a fire rated material when used on the interior of a building. Unlike solid insulation products that require careful measurement cutting and fitting spray foam can cover even the most uneven surface instantly.