What is an underlayment, and how much does it cost?
The three types
- Asphalt felt. The traditional option, sold as #15 and #30. Inexpensive, but it tears in wind and wrinkles when wet.
- Synthetic. Woven or spun polymer sheets, lighter and far stronger than felt, with printed lap lines. The most common choice on Georgia reroofs today.
- Self-adhered membrane. A peel-and-stick rubberized asphalt sheet that seals around nails. Used in valleys, around chimneys and skylights, on low-slope sections, and in a high temperature version under metal roofs.
How it shows up in your price
Underlayment is a small slice of a full replacement compared with shingles and labor, and moving from felt to synthetic changes the total only a little. Self-adhered membrane costs noticeably more per roll, which is why most roofs use it only where water concentrates. In an insurance estimate, felt and membrane are separate line items, so check that the type and quantity match what the roof needs. A typical North Georgia full replacement runs roughly $8,000 to $16,000 with underlayment included; see roof replacement cost in Georgia.
The word in other trades
Flooring installers say underlayment too, meaning the pad or panel under carpet, laminate or tile. On a roofing job, it always means the layer on the deck.
Why it matters in Georgia
When a summer storm blows a few shingles off, the underlayment is what keeps the ceiling dry until the repair. A strong synthetic, fastened with cap nails, buys you time. See synthetic underlayment vs felt.