Cedar Shake Specification
Shakes can be applied at a variety of gauges but, like Shingles, there
standard gauges. The minimum pitch shakes may be applied at is 20º.
a) Roofs 3 ply (3 course) shakes applied at a 190mm gauge = 1.39m²
b) Roofs 2 ply (2 course) shakes applied at a 250mm gauge = 1.83m²
c) Vertical (max gauge) shakes applied at a 290mm gauge = 2.12m²
N.B. These are exact areas and do not allow for cutting and wastage.
In addition for all cases allow extra for the following:
i) Starter Course, either
a. double course of shingles - 1 bundle to 9 lin.m. or
b. single course of shakes - 1 bundle to 7 lin.m.
ii) Valleys - 2 bundles for every 7.5 lin.m.
iii) Hips & Ridges* - 2 bundles for every 7.5 lin.m.(traditional
*There is no pre-formed capping available.
For maximum life, fixings should be made with 2 no. 45mm x 2.36mm
or stainless steel nails per Shake. As a guide 0.9kg of nails is required
for 4 bundles of Shakes.
3. Fixing Method
The Shakes are fixed as per Cedar Shingles directly on to the batten
at the specified
gauge. Shakes are normally fixed directly to the upper parts of the
avoiding conflict with the felt underlay nails) and applied in straight
single courses. A
starter/ eaves course of one or two layers of Cedar Shingles is overlaid
with a single
course of Shakes.
Hips and ridges are formed with alternative bevels laid to the same
gauge as the plain
For roof pitches of 20° - 30°, a breathable roofing felt interlay,
complying with BS 747:1977
Type IF, is required between the Shake courses to act as a baffle
to prevent the ingress
of wind driven snow or other foreign matter into the roof space.
The strips of felt should be fastened to the lower part of the next
batten exposed above
the head of the Shake, and the lower edge of the felt should be at
a distance above the
butt equal to twice the weather exposure. For example, 600mm Shakes
laid with a
250mm exposure would have felt applied 500mm above the butt. Thus
the felt will
cover the top 100mm of the Shakes and extend 357mm onto the sheathing.
the top edge of the felt must rest on the spaced sheathing.
As an alternative for steeper pitches where the slope of the roof
is over 30° a more
simple method of fixing may be used. A breather type of roofing felt
is laid over the
rafters and battened in the traditional fashion. We would recommend
using a 3 ply roof
construction in this case.
In conditions of severe climatic exposure or other exceptional applications,
contact John Brash & Company Ltd for further advice.