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The tell with O'Sullivan Installs is how often the same customers come back. Several reviewers describe a second and a third job — a front door first, then a storm door, then the windows; one wrote in October 2025 that they had used the North Billerica company on three separate occasions, for windows, doors and finally siding. Tim O'Sullivan owns the business, and the company says he personally inspects every siding, window and door installation. Its own site describes an exterior remodeling shop working across Massachusetts and New Hampshire with ProVia, SoftLite and Aeris products, behind a 10-year workmanship guarantee, a lifetime product warranty and 18-month interest-free financing. The Better Business Bureau grades it A+. Small jobs get the same treatment as big ones, by several accounts. In an October 2024 review, a customer who ordered one ProVia patio door said they got as much attention as a huge project would have drawn, with Brian working through the options with them. In April 2024, another wrote that O'Sullivan came out for a front-and-storm-door replacement — something a lot of other places they called wouldn't — took all kinds of measurements and walked them through customizing the doors. A July 2024 reviewer called it the most peaceful install of the 23 years they had owned the house, naming Ken's work and Brian's patience. The crew also turns up again long after the install. A September 2023 reviewer wrote that siding fitted three years earlier was hit by solar melt and that Tim's team took the problem on; in October 2023, another described a weatherstripping issue at the bottom of a ProVia door installed five years before. BuildZoom's permit filings run in the same direction: at least 44 jobs in three years across Lowell, Billerica, Belmont, Malden, Westford and neighboring towns, almost entirely window, door and insulated-vinyl-siding replacement, with a typical permit value near $11,000. Thirty Google ratings average 5 stars, and the written accounts run from 2021 to 2025. Price is the thing to raise up front. In September 2025, a commenter on r/ArlingtonMA called them "so expensive" while still calling it a good experience and the door "really, really nice"; a 2022 reviewer who collected several quotes put theirs right in the middle. If you want windows, doors or siding done once and done carefully, this is a reasonable call — get a written quote you can compare against others, ask exactly what the 10-year workmanship guarantee covers and who answers a callback years down the line, and check the company's registration on the state register before you sign.
“We used O’Sullivan Installs. So expensive. But overall a good experience, and the door we got is really, really nice.”
Recently had windows installed. Excellent experience. Brian, Estaban, Dan and Christina all knowledgeable and professional. Also very present, down to earth and good listeners. Five stars for sure.
We’ve used them on 3 separate occasions. For our windows, doors, and most recently siding. Great experience each time.
After using O'Sullivan Installs to replace our front door, two years later we had had them back to add a storm door and most recently they replaced windows in our house. Their quality and workmanship is top notch and I have referred them to at least 3 or 4 people who need windows and doors. They do quality work and you can tell by their craftsmanship that they care about what they do and take the time to install things correctly and also come back to check on things if you have any issues. When the building inspector came to close out our permit, he said they also did a good job. I bet he sees a lot of bad work! They clean up after themselves and leave no mess behind. I am so happy with our new windows and when we need the rest of our windows done, I know who I am calling!
Initial Disclaimer: I did not have any actual work performed by O'Sullivan Installs. I contacted them about getting a quote for replacing a storm door for my house. While I did not have O'Sullivan Installs perform any work for me the conversation I had with the company over the phone was enough to give me an idea of what working with the company would be like. The employee who called to discuss my request for getting a quote was polite, knowledgeable, honest, and up front about the type and quality of work that they perform. If you are looking to try and get something done as cheapy as possible and don't care how long it will last, you should look elsewhere. O'Sullivan Installs has a focus on quality and durability. I was given a very thorough explanation of why the company would not replace a storm door without also replacing the exterior door. This was not due to wanting to push more work on customers but because replacing a storm door without redoing the doorway would result in a storm door that would become misaligned within 6 to 12 months of being installed (my current storm doors issue). While I did not move forward with having work performed with O'Sullivan Installs due to plans on moving in the near future, I will be reaching out to first if I ever need to have any work done as the up front honestly about their company and work was extremely refreshing.
Great responsiveness, service and product. Other reviews were right, these guys deserve their rating. Have already recommended them to others.
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1 change recorded — last scanned Jul 30, 2026.
Typical Greater Boston range for this kind of work, from regional averages — not a quote from O'Sullivan Installs. Use it to sanity-check bids, then get the real number in writing.
Estimated range
$4,000 – $11,000
Typical exterior project around $7,500
One-day reroofs5.0
Roofs and siding done together4.8
No sales pressure4.7
Additions, attic and garage conversions4.5
Fixed a prior installer's mess4.5
