DCI Products RafterVent - Manual (Page 4)

4
Best-Practice
Wall Shingles
March/April 2007
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CoastalContractor
must be planned to account for the extra
thickness of the rain-screen “sandwich.”
I address some of the challenges this
presents here, but this is by no means an
exhaustive list. It will, however, give you
a foundation to come up with your own
solutions for those yet-to-be-encountered
trouble spots.
Pests and nests. Wasps and hornets
love to make nests in rain-screen spaces,
so along the bottom (intake) vent slot and
the top (exhaust) vent slot you need to
block bug entry. Simple strips of insect
screen wrapped around the edge of spacer
mat or battens are all you need. Slicker
Screen is a companion to Home Slicker,
and DCI’s CedarVent already has an
insect-blocking fabric covering. When
I’m not using those products, I staple
3- or 4-inch-wide screen to the bottom
edge of the wall before installing battens
or spacer mat (Figure 3). After the vent
material is applied, I wrap the screen
onto the face and staple it in place.
Once the trim or shingles are applied,
the screen is trapped securely.
Weaving shingle corners. Hand-weav-
ing outside and inside corners over Home
Slicker is a challenge. The shingles drift a
little when planning, because the fastener
shanks flex in the air space and the spongi-
ness of the matrix makes it hard to keep
the shingles from moving around. Rather
than get frustrated, I avoid the issue by
wrapping outside and inside building cor-
ners with 6-inch strips of
1 / 4 -inch plywood.
The plywood gives solid support for fasten-
ing and provides crisp lines to plane the
shingle edges to. For extra weather resis-
tance, I staple 16- to 24-inch-wide strips
of housewrap or building paper over these
plywood backing strips, letting it lap over
the edges of the Home Slicker.
Plastic battens don’t pose the same
trouble because they’re more stable. I run
the battens around the corner and weave
the corners like normal. The only tricky
FIGURE 3. Wasps and
hornets love to build
their nests in the vent
space of any rain
screen, so exposed
edges (at the bottom
and top of walls and
over windows and
doors) must be pro-
tected with screening.
Fastener selection: Use hot-dip galvanized, stainless steel, or
aluminum — not electrogalvanized — fasteners, especially in
coastal areas. I prefer stainless staples or nails for the best
performance, and they eliminate the chances of streaking.
Staples (16 gauge with 7 / 16 -inch to 1 / 2 -inch crown) and
nails (box type with blunt points) are both acceptable. The
fastener must penetrate through the shingles, vent space,
and all the way through the sheathing.
Fastener location: Place two fasteners per shingle about 1
inch above the overlying course line and
3 / 4 inch in from each
edge. If the shingles are wider than 10 inches (Cedar Shake
& Shingle Bureau) or 8 inches (IRC), apply an additional pair
of fasteners spaced 1 inch apart near the middle of the shin-
gle. Orient the pair of fasteners so the 1-inch space between
them is not within 1
1 / 2 inches of a shingle joint below.
Keyway spacing: When shingles are wet or green when
applied to the wall, it’s okay to butt the shingles edges
together. Dry shingles must be spaced apart to prevent
buckling when they absorb moisture and swell. As a rule of
thumb, I space shingles up to 6 inches wide with a
1 / 8 -inch
keyway. I space shingles that are between 6 and 9 inches
wide
3 / 16 inch apart. I space shingles wider than 9 inches
1 / 4 inch apart.
Joint offset: Joints in successive shingle courses must be
offset by a minimum of 1
1 / 2 inches (IRC and CSSB).
Keep in mind that if there are any defects in the top lap
of a shingle, you should space joints 1
1 / 2 inches away
from the defect. — M.G.
SHINGLE SPECS