A1 Unique Installations
“They did a tremendous job with our windows, quoted a very competitive rate, and left the house in perfect condition.”
Best Window Installers in St. Thomas, ON
15 companies listed · 4 in St. Thomas · 4 open weekends · 7 rated 4.5+
Data verified October 16, 2026
Talbotville Windows
“Talbotville Windows installed windows for us in a previous home 20 years ago and we were completely satisfied so recently we had them install a patio door for us.”
North Star Windows & Doors
“The only minor issue we had was with 2 sliding glass doors and a trim piece coming off, they sent somebody out within a week and made a permanent repair.”
Perfectfit Installations
“They have installed both doors and windows for me at different locations, and I would highly recommend them..”
Riverbend Windows & Doors Inc.
“Will be referring friends family and will use again when ready for more new windows.”
Heritage Renovations
“We had Heritage replace our front bay window a few years ago and my wife and I were extremely satisfied with the result.”
Listed for homeowners in and around St. Thomas, ON, these 15 companies fit and repair windows. Frame materials, glazing options and any credentials shown are taken from company websites; the customer lines are quoted from public reviews.
Area overview: St. Thomas, ON
4 of the 15 companies we list are based in St. Thomas; the other 11 serve St. Thomas from London (24 km) and Springfield (18 km). The companies on this page are rated from 3.9 to 5.0 across 858 reviews; 5 have 50 or more reviews and 7 are rated 4.5 or higher. When customers rate these companies on specific qualities, they most often praise professionalism (97%), quality (88%) and responsiveness (87%). The topics that come up most in reviews of the companies on this page are "price", "estimates" and "cleanliness". 4 are open on Saturdays and 1 on Sundays. 7 have ten or more years of experience, the longest 27 years. 1 offers emergency call-outs; 2 offer financing or payment plans; 8 give free estimates; 5 are family- or locally-owned and 2 list coupons or special offers. We have a website on file for all 15 of the companies on this page; 12 publish a contact page; 10 list a public email and 1 takes bookings online. We count these figures across the companies on this page; distances are straight-line, and hours and prices change, so confirm the details with the company before you book.
Is the home visit and measurement free?
A no-cost quote is offered by 8 of the 15 companies on this page. It comes with a sales visit, so agree how long it will take before they arrive. Ask for the quote in writing on the day, itemized by window, and be wary of a discount that disappears the moment the visit ends.
Four Seasons Sunrooms
“I was particularly impressed by the craftsmanship and diligence of the installer, Isaak who took on the daunting task in a way that was not intrusive to household activities.”
C.a.p.o.r. Renovations Inc.
“I would not hesitate to use them again and would highly recommend this company to anyone wanting quality installation and materials by an experienced local company who stands behind their work years after the job is done.”
Southwest Doors & Hardware
“We had Southwest Doors replace our company warehouse doors and the service provided was professional and top notch from quoting to installation!”
Thames Glass Limited
“She insisted that I write a review as she was so grateful for the professionalism, fair price and quality work.”
Affordable Home Services
“Abe (the installation team leader) and his team did a great job overall and we are happy with the results”
Raven Windows Inc.
“Was delivered on time, had good Installation, and I'm very satisfied with the quality.”
McCallum Aluminum Ltd
“The team was quick, efficient and tidy, and prices were fair.”
W D Dave Smith Renovations
“Great service have used their services before”
ADH Windows & Doors
“Amazing service , very professional and affordable.”
Why these companies made our list
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