What type of underlayment is required for wood shakes?

The correct type of underlayment required for wood shakes is number 30 felt. This choice is appropriate because number 30 felt provides a robust barrier that aids in moisture management and is more effective in preventing water infiltration than lighter options. It is also thicker and more durable, which is crucial for the longevity of the roofing system, especially since wood shakes can expand and contract due to weather changes.

Additionally, when using wood shakes as roofing material, proper underlayment is essential for maintaining an adequate water-shedding capability and minimizing the risk of leaks, as wood shakes are not entirely waterproof. Number 30 felt is designed to handle these vulnerabilities well, thereby providing a more reliable protective layer beneath the shaken roof surface.

While number 15 felt is often used for lighter roofing materials, it may not provide the same level of protection needed for more substantial wood shakes. Heavy-duty plastic underlayment, while also effective, might not be as traditional or suitable for wood shake applications, and fiberglass matting, though valuable in specific scenarios, does not provide the same moisture management properties tailored to wood shakes as number 30 felt does.