What does it cost to install underlayment?
Short answer. Underlayment is almost always installed as part of a full roof replacement, so its cost is built into the replacement price rather than charged as a separate job; the material itself is a modest share of the total. Where it shows up as its own line, such as in insurance estimates, it is priced per square of roof, with self-adhered ice and water barrier in valleys, eaves and around penetrations costing noticeably more than standard felt or synthetic.
Why underlayment is rarely a standalone job
Underlayment sits directly on the roof deck under the shingles. Replacing it means removing the shingles above it, so on a shingle roof, new underlayment and a new roof go together. The exception is tile and some metal roofs, where the roofing can be lifted, the underlayment replaced and the roofing reinstalled.
How it appears on estimates
- Field underlayment. Felt or synthetic, priced by the square across the whole roof.
- Ice and water barrier. Self-adhered membrane priced by the square foot or square for valleys, eaves where required, around chimneys, skylights and walls, and at low-slope sections.
- Labor. Included in the install line on most contractor quotes. Insurance estimates often list the material and installation together per square.
Factors that raise the cost
- More valleys, walls and penetrations needing ice barrier.
- Low-slope sections between 2 in 12 and 4 in 12, where code calls for a double layer of underlayment or a membrane.
- Mountain homes where ice barrier is run along all eaves.
- Upgrading to a higher-grade synthetic or full-coverage membrane.
What to check in your quote
Ask which underlayment brand and type will be used, where ice and water barrier goes, and whether it matches the shingle manufacturer's requirements for system warranties. A quote that says only underlayment with no type stated leaves room for the cheapest product. Compare options in synthetic underlayment vs felt and ice and water shield in Georgia.