On low slope applications, cover the deck with two layers of non-perforated asphalt saturated felt or two layers of a synthetic underlayment. One layer of an appropriate self-adhering modified bitumen membrane can also be used in place of a double layer of felt or synthetic. When using a double layer of felt or synthetic the starter course should be one half of the width of the underlayment plus 1”.
For example: a 36” wide roll of felt will have a starter course of 19” while a 54 8” wide roll of synthetic will have a starter course of 25”. Place a full width sheet over the started, with the long edge placed along the eaves and completely overlapping the initial started course. All succeeding courses will be a minimum of the full roll width and should be positioned to overlap the preceding course by one half the roll width plus 1”. Secure each course by using only enough fasteners to hold it in place until the shingles are applied.
The first course starts with a full shingle, while succeeding courses start with portions removed according to the style of shingle being applied.
By removing different amounts from the first shingle in each course, shingle joints or multiple thickness areas in one course do not line up directly with those of the course below, creating the desired pattern.
Installer must work from several bundles of shingles to help reduce shade variation
- Installer must ensure that each shingle has the correct number of nails per the manufactures requirements
- Check local building codes
- No racking installation permitted for certain shingle manufacturers.
Prior to installing shingles, a precut starter shingle must be installed. The starter strip protects the roof by filling in the spaces under the shingle joints of the first course of shingles. It should overhang the eaves and rake edges by ¼” to ¾”. Where the drip edge extends out from the eaves and rakes, the shingles may be cut flush with the drip edge with D style drip edge or extend out no more than ¾”.
If self-sealing shingles are used for the starter strip, remove the tab portion of each shingle and position the remaining strip with that factory applied adhesive face up along the eaves. Trim at least 5” from the end of the first shingle in the starter strip. Fasten the starter strips parallel to the eaves along a line 1 ½”-3” above the eaves. Position the fasteners so that they will not be exposed under the shingle ends in the first course.
Pre-cut starter strip shingles
Because of their factory-applied adhesive strips they will:
- speed installation time
- helping to prevent shingle blow-offs
- greatly reduce the possibility of leaking