Roof Rafter Bridging

For this size job you would want a large foam canister and professional spray applicator.

Roof rafter bridging.

It can consist of lateral members spanning in between trusses t or i bracing on individual members sheathing or metal strapping. In either case seal the foam edges well to the rafters with spray foam. Drive a nail into either end to hold the board in place. With steel framing at about r 04 per inch it s thermal bridging on a whole different scale.

Failure to mitigate can account for overall heat loss of up to 30 so it s not a thermodynamics lesson to be taken lightly. Most codes allow foil faced foam to be left exposed. The weight of the piano is centered over a single joist but the bridging transfers some of the weight to the adjacent joists. Structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes.

If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center. For example with bridging installed between joists a piano leg sitting over one 2 10 is actually supported by several. Place a short piece of framing lumber against the rafter above it so that the two boards form a continuous line. Plus you get the highest r value per inch for any type of insulation.

The main purpose for this type of bracing is to reduce the bucking length of the individual truss members and to assist in erection spacing of the trusses. The uninsulated roof framed with wood r value around 1 1 per inch means rafter lines covered with snow. It is always better to have a large rafter rather than be concerned with a sagging roof. Thermal bridging is the movement of heat through a material that s more conductive than the air around it.

The blocking or bridging between joists or rafters also contributes to this phenomenon.