The Starter Strip is the underlying asphalt shingle laid beneath the first course of an American Shingles roof. It provides protection by filling in joints that occur under the first course and along cut outs. It also provides for the sealing down/adhering of the tabs for the first course of American Shingles.
A number of different starter strips are used on American Shingles roofs based on the specific shingle profile being used. In some instances a proprietary dual layer system is used and is determined by CertainTeed for maximum warranty compliance in Australia.