Installation Guide

Figure 4: Certi-label Shake Application
Architect: Shope Reno Wharton, Photo: Robert Benson
GENERAL DESIGN AND APPLICATION DETAILS
4
Eave protection ( to rake edge)extend
Two nails (only) for each
shake approximately 3/4" from
edge and approximately 1 1/2"
above exposure line.
Rafter header
Fascia
Gutter
Adjacent course joints
should be offset
1 1/2" minimum
Rafter
Product should
project 1 1/2"
beyond the fascia
and approximately 1"
over the gable or rake end
Starter course
Exposure
Space shakes 3/8"
to 5/8" apart
Plywood sheathing
The bottom edge of the felt should be positioned
above the butt of the shake at a distance equal to
twice the weather exposure. Never interlay shingles
with felt.
Currently the only acceptable solid
sheathing product tested for use with
Certi-label shakes is plywood.
Certi-label Shakes
Certi-label Shake Application
A solid deck is recommended in seismic
activity, hurricane and tornado regions and in
areas where wind-driven snow is encountered.
Roofing felt system interlay between the shake
courses is required whether the sheathing is
spaced or solid. The felt interlay acts as a
baffle that prevents wind-driven snow or other
foreign material from entering the attic cavity
during extreme weather conditions. The felt
interlays also increase the roof's insulation
value. The felt interlay system forces water to
the surface.
If spaced sheathing is used in shake
application, the sheathing is usually 1 x 6
boards spaced on centers equal to the
weather exposure, (Table 4, Page 20) at which
the shakes are to be laid - but never more
than 7 ½” for 18” shakes and 10” for 24”
shakes on roof installations. When 1 x 4
spaced sheathing is installed at 10" on center,
additional 1 x 4 boards must be installed (i.e.
maximum allowable spacing is approximately
3 1/2" measured from edge to edge between
the sheathing boards). Please note that the
only solid sheet sheathing tested with Certi-
label™ shakes & shingles is plywood. Check
with your local building official for plywood
thickness/dimensions.
Special care should be taken when installing
the felt interlays over spaced sheathing to
ensure that an effective baffle is formed
(Figure 1). The felt should be applied over the
top portion of the shakes and extend on to the
spaced sheathing so that the bottom edge of
the felt is positioned at a distance above the
butt equal to twice the weather exposure.
Shakes, like shingles, are normally applied in
straight, single courses. The following
application details (Figure 4) must be
observed.
1. The starter course may be one or two layers
of cedar shingles or shakes overlaid with the
desired shake. A 15" shake is made
expressly for starter and finish courses.
2. Butts of first course shakes should project
1 1/2" beyond the fascia and approximately
1" over the gable or rake end.
3. The CSSB recommends using an 18" wide
strip of No. 30 ASTM D226 Type II or No. 30
ASTM D4869 Type IV roofing felt laid over
the top portion of shakes and extending on
to the sheathing. (Check with your local
building official for exact specifications in
your area). The bottom edge of the felt
should be positioned above the butt of the
shake at a distance equal to twice the
weather exposure. For example, 24" shakes,
felt extends up 14" onto the sheathing
forcing water to the surface.
4. Spacing between adjacent shakes should be
a minimum of 3/8" and a maximum of 5/8”.
5. Shakes shall be laid with a side lap of not
less than 1 1/2" between joints in adjacent
courses.
6. Straight-split shakes should be laid with the
froe-end (the end from which the shake has
been split and which is smoother) towards
the ridge.
Notes: See page 19 for high humidity areas.