What is the required method of installation for some models of asphalt shingles?

The correct answer is racking, which refers to a specific method of installation for asphalt shingles where the shingles are installed vertically up the roof in an aligned manner, rather than starting each row with a tapered piece. Racking can streamline the installation process and reduce waste, as it allows the installer to use full shingles without having to cut them for the starter course and can help create a clean, uniform look.

Utilizing the racking method is particularly beneficial in certain situations such as when roofing over existing shingles. This method is not only efficient but also aids in maintaining the water-shedding capabilities of the shingle layers. However, for racking to be appropriate, specific criteria must be met, such as ensuring that the roof is not too steep, and that the shingles being used are rated for this type of installation.

Understanding the nuances of shingle installation methods, such as when overlapping is typically used or the implications of accent or shingle-lap installation methods, is crucial for home inspectors as these methods can affect the longevity and performance of the roof system.