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Several insulation companies refused to even quote the attic. Green Stamp took the job — and the homeowner who wrote that in a 2023 review got an accurate quote, a fast installation date, and a crew that turned up on time every day until the work was finished. That is the kind of job people in Waltham call this company for: the awkward attic, the whole-house envelope, the retrofit somebody else walked away from. It works out of 184 Riverview Ave, and its BBB profile puts it at 23 years in business — incorporated in 2003 — with 19 employees. Its Massachusetts home improvement contractor registration is active, held by Green Stamp LLC. Reviewers are unusually specific about how the crews work. One, writing in January 2023, watched them arrive at 7:30 and go through to about 4:00 without stopping for lunch, spending the first couple of hours hanging plastic over the HVAC before any foam went in. A 2022 customer had a 4,500-square-foot house insulated in ten days and said it passed inspection on the first try, with everything in the house covered and the site cleaned afterward. Another 2022 homeowner came in through Mass Save, the state program that discounts insulation and air-sealing work. In a 2025 review, a former owner of S+H Construction said the company came back almost a year after finishing his own home renovation to touch up a few areas at no charge. Nineteen Google ratings average 4.7. The knowledge runs past the spray gun: a 2022 reviewer had heard Ben Marshal of Green Stamp speak at a construction supervisor licence renewal class about building energy code and where different spray foams belong, and noted he is a HERS rater. The one account pointing the other way is a decade old and very specific. A homeowner writing on BuildZoom in August 2014, also referred through Mass Save, said blown-in insulation opened a nine-foot crack in the dining room ceiling, pushed insulation across the room and cracked a bedroom wall, and that the company was not very helpful with the repairs. Settle that before anyone starts: what happens if the blow-in cracks plaster, and who pays for the patching. Green Stamp is a straightforward call for attic insulation, air sealing and spray foam on a difficult envelope, Mass Save jobs included. Get the damage-and-repair terms written into the scope, and ask who will be running your crew.
“Insulation Contractor Green Stamp Co. 184 Riverview Ave. Waltham, MA 02453”
As the former owner of S+H Construction, I have known Greenstamp for years. Last year we renovated our own home and Greenstamp did an outstanding job. They even came back almost a year later to touch up some areas at no charge. Great company !
Very professional, knowledgeable and pleasant to work with. Company came out, gave accurate quote, provided fast installation date, and was on time each day until the job was completed. Our house has a complicated attic, which several companies refused to even quote.. there were a couple of issues that occurred during install, but they very quickly resolved them! I would work with green stamp for any future insulation projects on our house. A+++
The men at Green Stamp arrived at 7:30 and worked straight until the job was done at around 4:00, not even stopping for lunch. They spent the first couple of hours just preparing the job, putting up plastic to protect the HVAC, etc., before they started spraying. They were very courteous and did a very good, clean job. I was quite nervous about having spray foam insulation in my home, having heard that if it's not installed correctly, I might have off- gassing. But Green Stamp was slow and careful, and the spray foam cured in a couple of hours, and there are no fumes whatsoever. Thank you Green Stamp! (Caitlin from Concord, Mass)
When we decided to age in place, it became clear that our home would require renovation and a small addition. Our goal was to create a structure with a conserving envelope, energy production, and high efficiency mechanics. The most challenging, by far, was the conserving envelope. In 2019, it was suggested that I contact Ben Marshall of GreenStamp. I called him, and most impressively, he came to the house, looked at the plans and explained insulation and the options to me. The project, which was to start in April 2020, did not begin till the fall of 2021. When it was time to insulate in the fall of 2022, Ben again came to the house to look at the areas to be insulated. For many reasons, this was a complicated project. The crew arrived with detailed instructions. The lead on the crew has worked at GreenStamp for fifteen years. A company does not get this kind of loyalty unless they are doing something right. His longevity with the company and with the installation of insulation was very reassuring. And he was well informed about the project. Over the months and years, Ben and Andrew had the patience of saints. They answered question after question, responded to email after email, understood my desire for a net zero envelope, and although they may have wanted to leave this project, they never did. They were timely and thorough in response. I think the most important aspects are their encyclopedic knowledge about insulation, their respect for their customers, their training and education of their employees, and the care they took with the installation. We could trust them implicitly. The insulating envelope of this building reaches net zero standards for this climate, is everything, I’d hoped for, and I can’t recommend GreenStamp highly enough. Jocelyn Tager
They just completed 4500sq ft home in ten days. Great job insulating - everything passed inspection on the first try. Also, they took care to cover every single item in the house and then did a good job cleaning. Awesome job!
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1 change recorded — last scanned Jul 31, 2026.
Owner on every job4.5
Insulation results3.9
Big-budget renovations4.4
