Asphalt shingles are designed for roofs with a minimum pitch greater than what ratio?

Asphalt shingles are specifically engineered for roofs that have a minimum pitch of greater than a 4/12 ratio. This means that for every 12 horizontal units, the roof rises at least 4 vertical units. The design of asphalt shingles requires this minimum pitch to ensure proper water drainage and to prevent issues such as water pooling, which could lead to leaks and damage over time.

On pitches shallower than 4/12, the risk of water infiltration increases significantly, especially in areas with heavy rainfall or snow. While some manufacturers may create products rated for lower pitches, the general guideline is to adhere to the 4/12 minimum for standard asphalt shingles to ensure maximum performance and longevity of the roofing system.