Why Long Island Homeowners Trust Thermo-Seal Window Installers
Looking for high-performance replacement windows in Suffolk County or Nassau County? Thermo-Seal delivers custom solutions designed to boost home value, comfort, and energy savings. Our expert team installs energy-efficient vinyl and composite windows built to handle the unique demands of Long Island’s coastal climate—keeping your home cooler in summer, warmer in winter, and protected all year round.
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Custom Window Options
We offer a full range of styles, all ENERGY STAR® rated and professionally installed:
- Double-Hung Windows – Easy to clean, classic design
- Casement & Awning Windows – Superior ventilation and seal
- Bay & Bow Windows – Dramatic curb appeal and light
- Sliding Windows – Smooth operation and space-saving
- Picture Windows – Expansive views, maximum efficiency
Every window is built with advanced glass packages to reduce heat loss, block UV rays, and lower your energy bills.
BAY & BOW
CASEMENT
DOUBLE-HUNG
GARDEN
PICTURE
SLIDING
BAY & BOW WINDOWS
Elegant Views, Expanded Space
Add architectural beauty and natural light to your home with Bay and Bow windows from Thermo-Seal. Perfect for living rooms, dining areas, or anywhere you want to make a statement, these windows create a graceful curve that expands interior space while maximizing your view. Choose from customizable configurations, seat board options, and energy-efficient glass packages—all designed for durability, comfort, and timeless appeal. Our expert team ensures a flawless installation that transforms both the inside and outside of your Long Island home.
CASEMENT WINDOWS
Sleek Design, Maximum Ventilation
Upgrade your home with casement windows from Thermo-Seal, offering a perfect blend of style, airflow, and energy efficiency. Hinged at the side and opening outward with a smooth crank handle, casement windows provide unobstructed views and superior ventilation—ideal for kitchens, bathrooms, and hard-to-reach spaces. Built with advanced sealing technology and high-performance glass, they deliver outstanding thermal insulation and weather resistance, even in Long Island’s coastal climate. Customize your look with multiple frame finishes, grille patterns, and hardware options for a clean, contemporary aesthetic.
DOUBLE-HUNG WINDOWS
Classic Style, Modern Efficiency
Thermo-Seal’s double-hung windows combine timeless appeal with cutting-edge performance, making them one of the most popular choices for Long Island homes. Designed with two operable sashes that tilt in for easy cleaning, these windows offer versatile ventilation, excellent airflow control, and low maintenance convenience. Each unit is built with multi-chambered frames, energy-efficient glass, and weather-tight seals to enhance insulation and reduce energy costs year-round. With a variety of finishes, grille designs, and hardware options, double-hung windows are a smart, stylish upgrade for any room.
GARDEN WINDOWS
Bring the Outdoors In
Create a charming showcase for plants, herbs, or décor with Thermo-Seal’s garden windows, designed to add sunlight and style to any room. Extending outward from your home, these windows create a mini-greenhouse effect that’s perfect for kitchens or breakfast nooks. With operable side vents for ventilation, energy-efficient glass, and durable, low-maintenance materials, our garden windows offer both form and function. Enjoy panoramic views and extra shelf space while brightening up your interior with natural light—all with expert installation and long-lasting performance tailored for Long Island homes.
picture WINDOWS
Expansive Views, Maximum Efficiency
Make a bold statement with picture windows from Thermo-Seal, designed to flood your space with natural light while offering uninterrupted views of the outdoors. These fixed, non-operable windows are perfect for living rooms, stairwells, or any space where you want to highlight the scenery and minimize maintenance. Built with high-performance insulated glass and airtight seals, our picture windows enhance energy efficiency, reduce outside noise, and deliver a clean, modern aesthetic. With customizable sizes and frame finishes, Thermo-Seal’s picture windows are a stylish, energy-smart choice for Long Island homes.
SLIDING WINDOWS
Sleek, Space-Saving Performance
Thermo-Seal’s sliding windows offer a perfect balance of modern design, easy operation, and energy efficiency—ideal for Long Island homes with limited exterior space. These horizontally gliding windows feature smooth-operating tracks, low-profile frames, and wide glass areas that bring in natural light while maintaining excellent insulation. With dual operable sashes and easy-to-remove screens, sliding windows are great for rooms where space is tight but ventilation is essential. Built to resist drafts, moisture, and wear, they deliver long-lasting performance with minimal upkeep—a smart, stylish solution for any home.
Get Your Free Quote Today
Ready to upgrade your windows? Contact Thermo-Seal now for a free, no-obligation estimate. Our local team is ready to help you choose the perfect windows for your home and budget.
Call 631-849-0434 or fill out the form to get started!
Professional Installation, Guaranteed Quality
Thermo-Seal’s certified installers handle every detail, from initial measurement to clean-up. No shortcuts. No surprises.
- Lifetime product warranties
- Satisfaction guaranteed
- Fully licensed and insured
- Flexible financing options available
What Our Clients Are Saying
We strive to make the entire home remodeling experience positive for our customers—from your first phone call, until the final handshake.
“I had a very good experience with Thermo-Seal. Chose them after interviewing many others because they’re local, communicated efficiently, and offered good midrange pricing and lifetime warranty. The crew did a fantastic job with the installation. They came early and finished 5 windows in 5 hours, and then they cleaned up. Highly recommended!”
Patrick B.
“We just completed a window and siding job for our home with Thermo-Seal. We are very impressed and satisfied with the quality of their products as well as the installation. I would recommend this company & I would use them again in the future if needed.”
Mindy L.
“The crew was a pleasure to work with, and we love our new windows. The installation was efficient, and the team was very professional. I’ve seen a difference in my heating bill since the install, which was our primary goal so we are very happy so far! I will work with Thermo-Seal again for a front door replacement when the time comes.”
Bonnie K.
“We hired Thermo-Seal for new windows and siding and I could not be happier! Their team is on time, professional, and meticulous about their work. You can tell they take pride in their output and ensure things are done correctly the first time around. The project completed ahead of schedule and we were kept in the loop the entire time. Very happy with their work and highly recommended!”
Sarah C.
“We were referred to Thermo-Seal by a neighbor who was very pleased with the results. We replaced seven windows and a sliding patio door are thrilled with the results and how much they enhance the appearance of our home. Without hesitation, we recommend Thermo-Seal for your home improvement projects.”
Frank D.
“Cannot believe how stress-free an experience it was dealing with Aaron and his team. Aaron was very patient with our multiple questions and never any sales pressure. The installation was clean, quiet and the installation team friendly and helpful. The windows were installed a few weeks before they were promised and there were no surprises. We will be strongly recommending Thermo-Seal to friends looking for replacement windows.”
David B.
