Eave Projection

The eave overhang gives some protection to the wall. Soffits are usually clad with prefinished perforated metal or vinyl panels (Figure 136). These are low maintenance and provide ample area for venting roof spaces without permitting insects to enter the space. A narrow eave projection is sometimes used on roofs with steep slopes. Soffits should not be used to vent rainscreen wall spaces.

Figure 136

Roof projection at eaves

Plywood was once commonly used for soffits and still is at times. Apply 6 mm (1⁄4 in.) sanded plywood nailed at 150 mm (6 in.) on centre along the edges and 300 mm (12 in.) 

at intermediate supports. Cut openings in the plywood to provide the required ventilation area and install screening. Butt the exterior finish to the underside of the soffit. Add a fascia board to the ends of the trusses or rafters and apply wood or prefinished metal fascia extending about 12 mm (1⁄2 in.) below the soffit to form a drip edge.

Special trim pieces are made for metal and vinyl soffit materials to provide support at the wall and at the fascia. For plywood soffits, nail a 19 × 19 mm (1 × 1 in. nominal) strip on top of the sheathing along the wall. This strip supports the inner ends of the blocking and edges of the soffit covering. Sloped soffits that follow the line of the projected rafter are sometimes used instead of horizontal soffits.


There are several ways to trim eave/gable-end intersections. The two most common methods of trimming the eaves at the gable end are as follows (Figure 137)

Figure 137

Eave and gable-end intersections (viewed from below)

Source : Canada Mortgage and Housing Corporation (CMHC)

Construction of Exposing Building Face and Walls above Exposing Building Face

Note : The eaves overhang at the edges of the roog structure and normally project beyond the side of a building. This will help to evacuate water away from the wall.