Roofing Felt Plays an Essential Role

Barry Stone’s reply to the home buyer asking about roofing felt (“Adding Drip Flashing to Roof Will Help Prevent Rotting Eaves,” Nov. 7) understates the importance of felt by describing it as a “backup waterproof membrane in case of leakage” beneath the shingles.

In fact, the felt layer is the primary waterproof part of a roof. The purpose of shingles, shakes or tiles on a roof is to protect the felt from weathering, not to waterproof the roof. Exposed to the elements by a missing shingle, felt becomes brittle and cracks, allowing water to penetrate the roof.

The existence of a ceiling stain should be taken as evidence that the waterproof integrity of the old felt has been lost and new felt should be installed. I learned all of this as a homeowner who recently replaced a leaking shake roof.

HAL MULLER

Thousand Oaks