Roof Curb Installation Detail

Installing curbs that rest in the flat lower panel area of metal roofing invites water tightness problems since the curb now has to be installed and sealed in the most vulnerable area the surface where rainwater flows.

Roof curb installation detail.

Curbs should be a minimum of eight inches above the finished roof and factory insulated to reduce condensation. A canted curb for example should be used for a built up or modified bitumen system roofing system. Roof curbs should be supplied by the hvac manufac. If the curb is mounted on the roof deck additional support is necessa ry directly below the curb flanges to minimize vibration.

Do not overlap counter flashing over the top of the roof curb. The curb can also be mounted on a roof deck. Contractors should not be asked to supply or install roof. Use tack welding or other suitable fastening method to secure the roof curb in place.

Install roof curbs rib to rib. A good penetration requires. If the roof curb will be mounted on a new building it can be assembled at any convenient location and installed as soon as the roof support members are in place. As a general rule the curb should be placed directly on the roof support members.

Turer to the general contractor or building manufacturer. First the basic design of the curb should take into account the roofing components so that it can be properly flashed into the roof system. Curbs should be sloped to avert water ponding. Trane recommends that the roof curb be placed directly on the roof support members and welded into place.

Curbs for roo fi ng systems.