Asphalt shingles installed in warmer climates with a slope of 4 in 12 or more should have what minimum underlayment?

In warmer climates, asphalt shingles installed on roofs with a slope of 4 in 12 or greater require a minimum of one layer of #15 felt underlayment. This underlayment serves several important functions. It acts as a secondary barrier to moisture, helping to protect the roof deck and the underlying structure from potential leaks that could occur at seams or around fasteners. Additionally, it provides a slippery surface that aids in the installation of shingles, allowing for efficient application and reducing the chance of damage to the shingles themselves during the installation process.

Choosing #15 felt is appropriate, as it offers a balance between cost and performance. While thicker underlayment options are available, such as #30 felt or synthetic underlayment, #15 is adequate for this application due to the slope of the roof and the climate conditions. It’s important to follow these guidelines to ensure roofing systems perform well and provide the longevity expected by the homeowner.