Technical Specifications

EXTERIOR NEW WALL CONSTRUCTION
Figure 1: Storypole
4
Figure 2: Spacing Detail
Design and Application Details
The instructions given here are not meant to
supercede local code requirements. Check
with your local building official for their
preference in your area.
Preparation - Be sure that the walls are
smooth, without protuberances. Nail ends or
points should be removed or pounded flush.
Underlayment - The CSSB recommends
Type 30 felt underlayment (also known as
#30 bituminous impregnated building
paper). Check with your local building
official for any questions about alternative
underlayment materials. Apply it
horizontally, with a staple gun, starting at the
base of the wall, with a 2" horizontal overlap
with each succeeding course, and a 6"
overlap vertically when starting a new roll.
Wrap the Type 30 felt underlayment 4" each
way around both inside and outside corners.
Corner Boards - Install corner boards
(Figure 8) at this time.
Flashing - Flashings associated with doors,
windows, and penetration details should be
in accordance with good building practice.
Laying Out - Determine the number of
Certi-label courses by measuring the height
of the wall at the lowest part of the
foundation, from a point 1" below the top of
the foundation, to the top of the wall. Divide
the height into equal parts, corresponding
closely to the weather exposure, but not
exceeding the maximum weather exposure
recommended. Transfer this measurement
and the number of Certi-labelcourses to a
storypole (Figure 1), to lay out courses on all
other walls. Whenever possible butt lines
should align with tops or bottoms of
windows or other openings, and for
appearance the exposure of the final course
at the top should match those below.
Certi-label Western Cedar
shingle and shake
size, exposure, width of joints, width of
product, kiln versus air-drying process,
moisture content and the local environment
will all affect the expansion/contraction of
Certi-label Western Cedar sidewall products.
These factors should always be taken into
consideration when determining the
installation details and adequate spacing
needed for your specific project. Consult
with your Approved Installer and refer to
Figure 2: Spacing Detail.
Figures 3a and 3b: To prevent the wicking of water, which may cause
staining, keep a 1/2” clearance between the first course of Certi-label products
from all surfaces below.
Leave a side lap of at least 1 1/2" between
joints in successive courses.
Number 1 Grade Certi-label Western Cedar
shingles spaced 1/8" to 1/4" apart (keyways
are 1/8" to 1/4" wide). These joints allow for
expansion and prevent possible “buckling.”
For every 4" width of dry Certi-label Western
Cedar shingle material, the product will expand
1/8". Therefore space keyways accordingly,
i.e.12" shingle is expected to have 3/8"
expansion. Allow minimum 1/4" keyway
spacing for Number 2 Grade Rebutted and
Rejointed Certi-label Western Cedar shingles.
Figure 3a: Flashing
Metal flashing
Belt trim detail at top
of footing wall
1/2" clearance to
bottom flashing
Figure 3b: Flashing
1/2" clearance to
bottom flashing
Certi-label Western Cedar wall shingles
Double coursing
Two last courses
over flashing
Metal flashing