Window Replacement & Installation
Upgrade Your View. Boost Comfort. Improve Efficiency.
At NISI Home Improvement, we specialize in window replacement that transforms the way your home looks and performs. From outdated windows that leak energy to broken frames and fogged glass, we replace your windows with high-quality, energy-efficient options that offer beauty, security, and long-term value.
Contact Us Now!
Proudly serving Nassau and Suffolk County exclusively
๐ Window Replacement: The Smart Upgrade
Old or damaged windows donโt just affect appearance โ they drive up your energy bills and reduce comfort. We help homeowners replace drafty, outdated windows with modern, durable, and stylish solutions.
Benefits of Window Replacement:
Lower heating & cooling costs year-round
Better insulation and noise reduction
Enhanced natural light and visibility
Smoother operation and easier maintenance
Increased home resale value

๐ ๏ธ Window Installation Services
Building a new space or adding windows to a remodel? Our expert team offers precision installation with clean, professional results โ every time.
We take care of everything, including:
Accurate measurement and custom sizing for a perfect fit
Careful removal of old windows or cutting new openings
Full insulation and weatherproof sealing to eliminate drafts
Trim, flashing, and exterior finish for a polished, seamless look
Post-installation inspection and cleanup โ your home stays spotless

๐ก๏ธ Why Choose NISI Home Improvement?
Licensed & insured installation specialists
Energy Star-rated windows from top manufacturers
Accurate, upfront pricing โ no surprises
Fast project completion with full cleanup
Local company with 5-star service reputation
๐ Letโs Get Your Home Sealed, Styled & Energy-Smart
Donโt let outdated windows hold your home back. Contact us today for a free in-home consultation and window replacement estimate.
๐ CALL: 516-860-5289
๐ Proudly Serving: Nassau & Suffolk County
Posted on Google![]()
Natum Sanchez2 November 2026Trustindex verifies that the original source of the review is Google.
Hi Marvin, Maggie and I wanted to personally thank you and your entire team for the excellent work repairing the roof and gutters and making the exterior of our home look immaculate. Your team was truly professional from start to finish, and we couldn't be happier with the results. We will definitely recommend you and your company to anyone in need of home improvements. Once again, we can't thank you enough for your hard work, attention to detail, and professionalism. Muchรญsimas gracias! Best regards, Nate & MaggiePosted on Google![]()
Urszula Zych23 October 2026Trustindex verifies that the original source of the review is Google.
Outstanding Roofing and Gutter Installation! I highly recommend NISI Home Improvement, Inc. for their exceptional work on our complete roof and gutter replacement. From start to finish, the entire experience was professional, organized, and stress-free. A special thank you to Marvin Guevara for his outstanding customer service, professionalism, honesty, and attention to detail. He took the time to explain everything, answer all our questions, and make sure we were completely satisfied. The crew did an amazing job installing our new Owens Corning roof, replacing the skylight, and upgrading our gutters and downspouts. Their workmanship was excellent, and they treated our property with care, leaving everything clean and spotless. The quality of work exceeded our expectations, and our home looks beautiful! If youโre looking for a reliable, knowledgeable, and professional roofing company, NISI Home Improvement is an excellent choice. Thank you, Marvin and the entire NISI team, for a job exceptionally well done! Highly recommended!Posted on Google![]()
Michael Tucciarone23 October 2026Trustindex verifies that the original source of the review is Google.
Siding repaired for new electrical meter installation. Great jobPosted on Google![]()
Marco Antonetti21 October 2026Trustindex verifies that the original source of the review is Google.
โญโญโญโญโญ NISI Home Improvement โ Outstanding Work, Exceptional Service, and Unmatched Quality! I couldnโt be happier with the work NISI Home Improvement did on my home. They installed new windows, siding, a roof, and a beautiful new front door. They also built out the soffits and overhang for a new porch, and the finished result is absolutely amazing! From start to finish, the entire experience was outstanding. The team was extremely responsive, thorough, and professional throughout the entire process. Every step of the way, they took the time to explain my options, answer my questions, and guide me toward making the best possible decisions for my home. The quality of their workmanship was exceptional, and it was clear that they take tremendous pride in what they do. What really sets NISI Home Improvement apart is their integrity and attention to detail. They donโt cut corners, they donโt nickel-and-dime you, and they consistently go above and beyond to make sure everything is done right. They genuinely care about the quality of their work and making sure their customers are happy. Finding a contractor you can trust to deliver outstanding results, communicate effectively, and treat your home as if it were their own is not easy. NISI Home Improvement exceeded my expectations in every way. I would recommend NISI Home Improvement without hesitation to anyone looking to improve their home. If you donโt use this company, youโre making a big mistake! I couldnโt be happier with the results and would absolutely use them again.Posted on Google![]()
Rebecca Baffi15 October 2026Trustindex verifies that the original source of the review is Google.
Rey was the best to deal with. They did such a great job.+0Posted on Google![]()
Dan Hunt3 October 2026Trustindex verifies that the original source of the review is Google.
Awesome Job! Done on time. I liked to deal with Marvin.Posted on Google![]()
Ashok Sharma30 September 2026Trustindex verifies that the original source of the review is Google.
Job was done on, I am very pleased with their work.Posted on Google![]()
Jacqueline Charlton29 September 2026Trustindex verifies that the original source of the review is Google.
NISI does excellent work, The workers are efficient and professional, This is the third time I have used this company. I will always recommend.Posted on Google![]()
Michael O'Leary28 September 2026Trustindex verifies that the original source of the review is Google.
I hired NISI to replace my roof last fall. Nelson came out and quickly provided me with a detailed estimate of the project. The estimate was less than other companies had provided Nelson was great to work with and was on the job site from start to finish. I canโt say enough of how easy Nelson was to work with, answering all questions and explaining in detail the work involved. They even encountered a broken vent pipe and were able to secure a plumber to complete the work immediately. This was no small matter and was handled quickly and efficiently The job was completed within the timeframe presented and my property was thoroughly cleaned afterwards I cannot say enough how pleased I was with hiring NISI to replace my roof I can highly recommend NISI for roofing but I would expect that their same high level of professionalism would apply to any of the services they providePosted on Google![]()
Aimee Hsu23 September 2026Trustindex verifies that the original source of the review is Google.
Easy, straightforward process. Rey and his guys were great to work with. Respectful and did a great job fixing our leaking skylight. Would definitely use them again.