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Certi-label™ Shakes
In shake application spaced 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 1/2" 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 shakes and shingles is plywood. Check with your local building official for plywood thickness/ dimensions. A solid deck is recommended 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 insulating value. The felt system interlay forces water to the surface.
Special care should be taken when installing the felt interlays over spaced sheathing to ensure that an effective baffle is formed (Figure 4). 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.
Certi-label™ Shake Application
Shakes, like shingles, are normally applied in straight, single courses. The following application details (Figure 4) must be observed.
- 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.
- Butts of first course shakes should project
1 1/2" beyond the fascia and approximately 1" over the gable or rake end.
The CSSB recommends using an 18" wide strip of Type 30 roofing felt laid over the top portion of the 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.
- Spacing between adjacent shakes should be a minimum of 3/8" and a maximum of 5/8".
- Shakes shall be laid with a side lap of not less than 1 1/2" between joints in adjacent courses.
- 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.
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