The basic steps for estimating and installing wood shakes and wood shingles are same as those for any steep slope material. There is one important difference, however. By design, wood shakes and wood shingles are all different in size so there are no vertical guidelines needed. Horizontally, the guideline is provided by the felt interply, or chalk lines.
The first step in installing a wood shake or wood shingle roof is to estimate the material requirements. Once again, we determine the same seven dimensions and the same four quantities. The dimensions and quantities required are:
The coverage for wood shakes and wood shingles will vary depending on the exposure specified. Always estimate material quantities based on the specified exposure.
The eave of the roof will require a double course of shingles. With shakes, one square will cover about 36.6 m (120 ft). Also, for every 30 m (100 ft) of valley allow two square of shakes. Hand split roof shakes also require an underlay of asphalt felt 450 mm wide (18 in) interlaid between each course.
Number of Bundles
After determining the required area and lengths you can estimate the total material needed. When you are using 600 mm (24 in) wood shakes at 250 mm (10 in) exposure, estimate quantities using the following guidelines:
Area – 5 bundles per square
Capping – 1 bundle per 4.9 m (16 ft)
Valleys – 1 bundle per 1.5 m (5 ft)
Starter Course – 1 bundle per 7.3 m (24 ft)
When you are using 450 mm (18 in) wood shingles at 140 mm (5 1/2 in) exposure:
Area – 4 bundles per square
Capping – 1 bundle per 4.9 m (16 ft)
Valleys – 1 bundle per 3.8 m (12.5 ft)
Starter Course – 1 bundle per 18.3 m (60 ft)
A waste allowance of between 5 and 10 percent should be calculated when you are determining
the total material requirements.
Number of Lengths of Flashing
Flashing for perimeter and horizontal sidewall projections can be calculated. Step flashing used on vertical sidewalls and chimneys will vary depending on the exposure of the shakes and shingles. Step flashing must always have a minimum 75 mm (3 in) head lap. As an example, if you are using a 250 mm (10 in) exposure on wood shakes, you will require a length of flashing a minimum 300 mm (12 in) long for every 250 mm (10 in) length of wall. Metal valley flashing must be lapped a minimum 150 mm (6 in). So, take this into account when determining the total valley lengths.
Eave Protection and Underlayment
Material chosen for eave protection will vary depending on the method of installation. Check the labels of the material specified and apply this to your determined area.
2 ply #15 asphalt felt – 1 roll covers 2 squares
1 ply #30 asphalt felt – 1 roll covers 2 squares
Underlayment used on wooden shingle roofs must be vapour permeable. #30 felt, 450 mm (18 in) wide used for interply between courses of wood shakes can be estimated at 1 1/2 rolls per square when you are using a 250 mm (10 in) exposure.
Nails, Vents and Adhesives
Quantities of nails and vents can be estimated as outlined previously. Ensure nails are of sufficient length to penetrate a minimum 12.7 mm (1/2 in) into the sheathing at all times, including capping.