Roof Types / Underlayment
Underlayment
The hidden waterproof layer that is the true first line of defense beneath your roofing material.
Underlayment is the waterproof membrane installed directly on your roof deck, beneath the visible roofing material. While you never see it, underlayment is arguably the most critical component of your roofing system. It provides a secondary water barrier that protects your home when wind-driven rain gets beneath shingles or tiles, and it is the primary waterproofing layer on tile roofs where the tiles themselves are not sealed. Modern synthetic underlayment has largely replaced traditional felt paper, offering superior tear resistance, UV stability, and moisture protection.
Why It Matters
Underlayment failure is the number one cause of leaks on tile roofs in the Bay Area. The tiles themselves can last 50-100+ years, but the underlayment beneath them degrades after 25-35 years. When a tile roof starts leaking, most homeowners assume the tiles are the problem — but in 90% of cases, the underlayment is the culprit. Replacing the underlayment (tile restoration) rather than the entire roof saves 40-60% and is the most common major service we perform on Bay Area tile homes.
Underlayment FAQ
What is the difference between synthetic and felt underlayment?
How do I know if my underlayment needs replacement?
Need Underlayment Work?
Schedule an inspection. We will assess your underlayment and recommend the most cost-effective solution.