Which roofing type is not recommended for slopes below 8.5 degrees?

Asphalt shingles are generally not recommended for slopes below 8.5 degrees due to their design characteristics. They rely on gravity to shed water effectively, and a slope below this threshold increases the risk of water ponding. When water accumulates on a flat or low-slope surface, it can lead to premature degradation of the shingles, decreased lifespan, and potential leaks.

Different roofing types have varying degrees of suitability for low-slope applications. For instance, slate roof systems are more versatile and can handle low slopes better than asphalt. Liquid applied systems often create seamless membranes ideal for low-slope roofs, while PVC roofing is designed to withstand different environmental conditions and can perform adequately on low slopes. Therefore, understanding the specific requirements and limitations of each roofing type is crucial for making an informed decision when it comes to installation on low slopes.