Guide
Felt or synthetic underlayment: which field layer the estimate should specify
Written by Ultra Power Construction. The credentials page states that this contractor is licensed and insured in New Jersey and lists GAF and Owens Corning programs. Updated 2026-09-28.
Essex Fells, North Caldwell, and Harding Township estimates still sometimes say only “underlayment” without choosing felt or synthetic for the field. The decision is which product covers the deck between ice-and-water zones, and whether that choice is written before installation.
- Felt and synthetic behave differently on the deck
- The field layer is separate from eave membrane
- What the underlayment line must say
Felt and synthetic behave differently on the deck
Traditional felt can wrinkle when wet and offers less tear resistance underfoot. Synthetic underlayment is lighter, often more slip-resistant, and covers faster—but it is still not a substitute for ice-and-water at eaves.
The field layer is separate from eave membrane
Ice-and-water at eaves and valleys plus synthetic or felt in the field is a common combination. Naming only one product leaves the layout ambiguous.
What the underlayment line must say
Product type for the field, ice-and-water locations, and lap rules. A North Caldwell or Harding Township bid that says “felt included” without the eave plan is incomplete.