Stormtite

Watertown's Inspectional Services Division does not require a permit for a same-size, same-opening sash replacement on a single-family or owner-occupied unit. Any enlargement, header change, or conversion of a window into a door is permitted as construction. Multi-family and condo work usually needs association sign-off in addition to any town permit, especially when exterior trim or grille patterns change. Most of Watertown's housing predates 1978, so RRP lead-paint rules apply on the majority of jobs — expect a $50–$150 per opening lead-safe surcharge.

Replacement window pricing in Watertown is close to the Boston-metro average, with multi-family work running slightly higher per opening because of access and staging. A quality vinyl double-hung runs roughly $550–$1,100 per opening installed; wood and composite (Andersen, Marvin, Pella) runs $1,300–$3,000. Entry-door replacements range $1,800–$5,000 with sidelights and a quality lockset. Patio sliders on rear porches and three-deckers typically come in at $2,500–$5,000 installed.

Massachusetts requires a written contract and a Home Improvement Contractor registration for most residential window & door installation work; ask for the registration number and check it before paying a deposit.

More on permits, costs, rebates and common questions, plus every other window & door installation contractor serving the town, on the Windows & Doors in Watertown page.