DCI Products RafterVent - Manual (Page 3)

3
wrapped walls, and the matrix compresses
a little when the shingles are installed on
top, leaving an effective
1 / 4 -inch air
space. The corrugations should be ori-
ented vertically for the best drainage and
airflow, and the edges of the mat should
not be overlapped.
On the plus side, Home Slicker is only
1 / 4 inch thick — not nearly the 3 / 4 inch my
furring strips padded out the shingles. The
butt lines of each shingle course laid over
Home Slicker flush out with
5 / 4 -inch cor-
ner boards applied directly over the house-
wrap. And the butt lines come close to, but
not past, most flanged window jambs. The
sheets go up quickly with no special lay-
out, but it is important to cut Home
Slicker close to trim such as window cas-
ing and corner boards. If you leave a wide
space (
3 / 4 inch or more), the unsupported
shingle edge is likely to split.
On the downside, fastening shingles
over Home Slicker takes a deft hand.
The bottom few shingle courses are the
hardest to install. The matrix is spongy, so
hand-driving nails is a challenge, and
pneumatically driven staples or nails eas-
ily overdrive even with the air pressure set
low. You’ll end up splitting more shingles
in the first two rows than on the rest of
the wall. Subsequent courses are sup-
ported by the shingles beneath, so the
going gets a little easier. There’s a notice-
able cushioning of hammer blows when
hand-driving nails into shingles applied
over Home Slicker. The bounce makes it
hard to start nails in the shingles. You
must also use fasteners long enough to
pass through the vent space and pene-
trate all the way through the sheathing.
Plastic battens. Corrugated plastic
battens offer a good alternative to my fur-
ring-strip rain screen. These have hollow
channels that let water and air flow
through them (Figure 2).
The only ones I’ve found marketed
specifically for shingle installation are those
from DCI Products — CedarVent and
RafterVent — but similar products are
available (see “Resources,” page 7).
Standard CedarVent comes in strips 3 feet
long. The four-ply version is
3 / 4 inch thick
by 2 3 / 4 inches wide. But a two-ply version
that’s just 3 / 8 inch thick (my preference)
and a three-ply version that’s 9 / 16 inch thick
are also available. While 1 1 / 2 -inch-wide
strips can be special ordered, I typically just
rip the two-ply version in half (from 2
3 / 4
inches down to 1 3 / 8 inches) to save mate-
rial and expose more of the shingle back to
the air. CedarVent is wrapped with a thin
fabric to keep insects out, so it’s great along
the undercourse at the bottom of the wall
and last course at the top. RafterVent can
be used instead of CedarVent in the field of
the wall. It’s essentially CedarVent without
the fabric wrap.
Battens require precise placement, so
they aren’t as fast to install as spacer
mats, but they do provide solid support for
nailing. I lay out a story pole for shingle
course exposure and use it to mark loca-
tions for the battens. After I transfer these
layout marks onto window and door trim
and corner boards, I snap chalk lines on
the housewrap between my marks. The
battens get applied above the lines. Since
shingles are nailed about 1 inch above the
butt line of the overlapping course, the
battens are positioned perfectly behind
the nail line. Extra battens are needed
under windowsills and horizontal band-
board trim elements to support the top
edges of the shingles.
Other than selecting longer fasteners,
there’s no special precaution to applying
shingles over battens.
TRIM DETAILS
The devil is always in the details. Corner
boards, woven corners, window and door
trim, band boards, and other trim elements
Best-Practice
Wall Shingles
March/April 2007
~
CoastalContractor
FIGURE 2. Plastic battens have hollow channels that let water and air flow through them.
Shown here is the two-ply version of CedarVent, which the author rips to 1 3 / 8 inches wide
to save material and expose more of the shingle back to air.