- Q.How should we detail wood
shingles on dormers? Are the ridge shingles clipped on the same
way as asphalt shingles? Is there a trick to getting the valley
flashing to lie flat? What other details are
important?
A. The ridge shingles should be
attached with alternate overlaps, similar to the way a woven
corner is detailed on a wall. The exposure should equal that of
all regular courses of shingles. Note that longer nails will be
necessary for the ridge shingles. Shingles on the sides of
dormers need not be clipped at the top.
To keep the metal valley flashings lying flat, do not nail
them directly to the roof sheathing. Instead, fasten them with
clips nailed to the sheathing and locked into the rolled edge
of the flashing. This allows the flashing to move with
temperature changes. The shingles should not be nailed through
the metal. Valley flashing should overlap 6 inches at end
joints, and flashing sheets should be no longer than 6
feet.
The most critical part of installing a wood shingle roof,
other than the flashing, is the nailing. Each nail should be
driven not more than 3/4 inch in from the edge of the shingles
and no more than 1 inch above the exposure line. The nail heads
should be driven to the surface of the shingle, not indented
into the shingle fibers. The shingles should overhang the rake
edge 1 inch and the fascia a minimum of 1 1/2 inches. If
gutters are used, the shingle may overhang by 1 inch. The slots
between shingles should be 1/4 inch to 3/8 inch wide, and
offset from the slot in the course below by at least 1 1/2
inches.