How Much Should Roof Sheathing Overhang

Roof sheathing overhang on fascia.

How much should roof sheathing overhang.

Some slight overhang is recommended in conjunction with a drip edge flashing to prevent water from getting under the roofing and onto underlying wood. The drip edge also gives us a nice straight edge with which to align roof shingles slates or other roofing material. A typical metal roof overhang may be 2 to 4 inches or even less. Measure up the rafter 45 3 4 inch from the cut end of the truss tail and snap a line along the trusses.

Overhangs can vary from a few inches to a few feet depending on preference. The edge of the shingles should hang over a roof between an inch and an inch and a half or between a half inch and three quarters of an inch if drip edge flashing is installed. Metal is usually installed on rafters or strip sheathing rather than the solid decking used under other materials. However the suggested width of an overhang is between 12 and 18 for eaves and no more than 8 for rakes.

Too little can allow water to seep into rake or fascia boards. I ve trimmed my roof sheathing to run between 5 8 and 3 4 over the sub fascia. Slide the sheet one rafter width over the end of the roof so the edge is centered on the next rafter offset one rafter spacing from the first piece of installed sheathing from the row below. Drip edge varies in dimensions but typically the flange that nails to the roof surface is about 2 5 wide and the vertical edge that directs roof runoff down and away is about 1 5 in depth.

This is to just enough to cover the 3 4 x6 actual fascia. Too much overhang and the shingles could blow off in high winds. Now that i ve modeled what i was going to build i decided i need a piece of molding to break up the plain look of just the fascia trim plank.