Technical Specifications

EXTERIOR OVER-WALL AND RE-WALL CONSTRUCTION
Figure 12: Typical Window and Door Casing Detail
Figure 15: Over Stucco Detail
Figure 13: Over Beveled
Siding Detail
10
Design and Application Instructions
Re-walling
Once the old exterior wall material has been
removed and the old nails or other
protrusions cleaned away, the new wall can
be applied. Type 30 felt underlayment
should be applied since it is new
construction.
Over-walling
Applying Certi-label Western Cedar shingles
or shakes right over an old wall - whether
wood, brick, stucco, or synthetic products - is
easily done. It saves time involved in both
removing the old exterior and in disposing of
it. However, avoid nailing over vinyl or
aluminum as they are not sufficiently strong
to provide a proper support.
First, nail moulding strips on the face of
existing window and door casings, flush with
the outer edges. The Certi-label Western
Cedar shingles or shakes are then joined to
the mouldings (Figure 12).
Over Beveled Siding - Applying a new
Certi-label Western Cedar shingle or shake
wall over old beveled siding can be
accomplished in either of two ways: 1) By
filling in the low points of the wall with low
grade lumber or plywood strips (called
horse feathers) of appropriate thickness and
thereby increasing the potential nailing
surface, or 2) by nailing the Certi-label
Western Cedar shingles or shakes to the high
points of the bevels of each course of the old
wall, or of alternate courses (provided it
does not result in weather exposure greater
than is recommended (Figure 13).
Ensure that the first course is properly
attached. All Certi-label Western Cedar
shingle and shake product installation must
meet nailing and exposure guidelines as
detailed in this manual. It may be necessary
to add occasional nailing strips.
Over Masonry - Masonry walls are easily
covered, by vertically furring the walls and
applying nailing strips (1 x 3 or 1 x 4) spaced
according to the exposure and single/double
course product design. The nailing strips
should be fastened with special nails, driven
between the bricks or blocks, so that the
outer shingled wall will be firmly attached
(Figure 14).
1 x 3 or 1 x 4 nailing
strips spaced according to
exposure of Certi-label
Western Cedar shingles or
shakes, regardless of
single or double course.
(See pages 6-7 )
Over Stucco - Nailing strips should be
attached with nails long enough to penetrate
the stucco and the underlying sheathing. Do
not apply directly to the stucco, which is too
weak to provide a proper support. If the old
stucco is removed, new Type 30 felt
underlayment is then applied to the walls,
and the shingling can proceed as in new
construction (Figure 15).
1. Apply new casing to bring Certi-label Western
Cedar shingles or shakes flush with surface
2. The integrity of the original flashing is to be
utilized. Additional trim is considered to be
decorative only. If the original window does not
have good structural integrity, it must be
removed and a new one installed. New casings
are to be installed as part of proper wall
construction as shown throughout this manual.
2
Furring if required
1
Figure 14: Over
Masonry Detail
Double starter course
Double starter course
Double starter course