Overhang

Overhang is the portion of the truss that extends beyond the outside bearing of the structure, creating an eave for the building. Overhang length can vary from as small as 6” to as great as 36” in certain applications. Longer overhang lengths are certainly possible, but may require some sort of support, either as a structural fascia board or beam to support the overhang. For a pitched roof application, the overhang is subject to the slope of the top chord and in longer overhang scenarios can create conflicts with header heights for windows and doors.

Overhang material is typically the same as the top chord material, as it is usually the same member, just extended. Some truss technicians will create a splice joint near the bearing to differ the overhang material from the top chord in a cost saving method or to meet specific architectural requirements in the construction documents. Special considerations should be made in cases where the truss overhang will be exposed once the structure is complete. Overhang members should be culled for visual appearance and precautions are recommended to protect the overhangs of trusses shipped in inclement weather to protect from mud, road grime, and other hazards.

Most component manufacturers will manufacture and ship overhangs at the full width requirement anticipating the truss installers to trim them back for a fascia board to create an even, consistent overhang with a striking visual appearance. Trimming the overhang removes small, yet obvious, visual inconsistencies caused by a variety of factors: how the truss was set on the bearings, how it was manufactured, how the bearing is positioned, or any combination of these. An example of this is a truss with a 24” overhang that will be trimmed back to 22 ½” in the field with a 2X sub-fascia to finish at the full 24” per the construction documents. Alternatively, some component manufacturers will reduce overhangs by 1-½” anticipating a 2X sub-fascia member applied in the field. This is quite common when the overhang is actually a cantilever and any modification to the truss would jeopardize the integrity to the heel joint.

A majority of overhangs are cut and manufactured with a plumb Cut, where the end of the overhang is cut with a vertical orientation. In addition to a plumb cut, overhangs can have a square cut, horizontal cut, or double cut. A square cut overhang is cut square to the 2x member typical of how an unaltered rafter member would appear if it were used, resting on the bearing at a particular pitch. A horizontal cut overhang is cut level or parallel to the bearing. A double cut utilizes both a plumb cut and horizontal cut in order to minimize the fascia line. It is a great way to downsize fascia appearance on an oversized top chord member. For instance, a girder truss with a 2x8 top chord and overhang can be double cut to match adjacent 2x4 top chord trusses.

Overhangs can also include a soffit return that provides support for certain soffit types. It is a horizontal member that is plated to the end of the overhang that returns back to the bearing but is cut short so not to interfere with the wall sheathing or other parts of the bearing during installation.

Overhangs provide an important architectural element to a structure and truss design relative to overhangs have significant implications for exterior finishes.  

0
0