Underlayment is a critical component beneath clay tile roofs, serving as a protective barrier between the tiles and the roof deck. It helps prevent water infiltration caused by rain, wind-driven moisture, or broken tiles. For clay tile roofs, the underlayment typically needs to be a high-quality, waterproof material such as synthetic underlayment or specially rated felt, designed to resist moisture and withstand high temperatures since clay tiles can get very hot in the sun. This layer also plays a role in protecting the roof during installation before the tiles are fully in place. Improper or missing underlayment can lead to leaks, wood rot, or mold, especially if your roof deck is exposed to the elements for extended periods.
If you want to check your underlayment as a homeowner, a safe DIY method is to inspect the attic after a rainfall for any signs of moisture or water stains on the ceiling. You can also look under loose or damaged tiles if accessible without risking injury or damage. If you notice wet spots or the felt-looking layer is visibly torn or brittle, it’s a sign of underlayment failure. When calling a roofer, ask specifically what type of underlayment they recommend for your climate and tile style, ensuring it meets local building codes and the tile manufacturer’s warranty requirements. A good question to ask is, “Can you provide documentation that your underlayment choice is suitable for my specific clay tiles and local weather conditions?” and “How do you handle underlayment installation to make sure it maintains its waterproof qualities during and after tile placement?”