Trusted Window Installation Experts Serving Long Island
Whether you're replacing old windows, upgrading to more efficient models, or installing new units for renovations and extensions, NJM Mechanical and Contracting delivers precise, code-compliant window installations. With over 33 years of experience, we guarantee clean workmanship, proper sealing, and long-lasting performance for every home.
We work with a variety of window types and offer solutions tailored to your home’s structural layout, design preferences, and efficiency needs.
Expert installation of new windows for additions, renovations, and upgrades with precise fitting for long-term durability.
Upgrade your home with modern, energy-efficient replacement windows that reduce drafts, improve insulation, and enhance comfort.
Professional reframing and structural realignment to ensure windows are properly supported and integrated into your home’s architecture.
Expert Window Installation Backed
by Over 33 Years of Experience
Why Choose NJM for Your Window Construction Project
We are fully licensed and insured to perform residential window installation, replacement, and structural modifications.
We are fully licensed and insured to perform residential window installation, replacement, and structural modifications.
We install high-performance windows designed to reduce energy consumption, improve comfort, and lower utility costs.
Our team ensures proper fitting, sealing, insulation, and protection from air leaks or water infiltration.
We handle all framing, alignment, and finish work to ensure your new windows look natural and function flawlessly.
Decades of professional experience mean we install fixtures, piping, and full systems correctly the first time — with workmanship that lasts.
No hidden charges or surprise add-ons. You’ll receive a clear estimate outlining exactly what your installation includes.
Structural Opening Inspection
Assessment of the window opening, framing, and support to ensure safe installation.
Glass & Frame Integrity Check
Full inspection of window glass, frames, locks, and hardware for smooth operation and safety.
Water & Weatherproofing Review
Verification of flashing, sealing, and waterproof barriers to prevent leaks and moisture issues.
Code Compliance Review
Ensuring installations meet Nassau and Suffolk County building requirements.
Insulation & Air-Seal Evaluation
Ensuring proper insulation and air sealing for maximum energy efficiency.
Final Fit & Finish Inspection
Comprehensive review of trim, caulking, alignment, and operational performance.
Trusted Installation Expertise for Long Island Homes
Our Window Installation Safety & Inspection Services Include:
NJM provides thorough inspections and installation checks to ensure every window is properly sealed, secure, and compliant with Long Island building codes.
Find Contracting Services Near You!
Service Area Links:
- Long Island
- Nassau County
- Suffolk County
What Our Long Island Clients Are Saying...
Kris
I couldn’t recommend Neil enough! From start to finish him and his team were professional, efficient and experienced. We had a job pulling up rocks and putting top soil down which I know can be a tedious job. We appreciate the work and look
Evelyn Powers
We had an ongoing issue with clogs. My daughter woke up to flooding in her bedroom from her toilet, which was not fun! This was our first time having NJM in our home. Neil was knowledgeable and gave us several options. we chose to have him use the camera to get to the root of the problem. He was able to pinpoint several issues and was able to fix clog and clean out the pipes. Neil and his crew were very professional,
Irene Cheung
I contacted NJM Mechanical because I didn’t have hot water anywhere in my house. Neil was able to diagnose the issue and get to work. My navien tankless water heater is only a year old and still under warranty. Instead of waiting on Navien to send the part so the issue can be corrected, Neil went out, found the part, purchased it,
William Lo
Great experience. Neil came out and took the time to explain everything thoroughly. He was able to fix all the errors on our Navien and have it back up and running. Following up a week later. Neil and Mike came out to redo the Navien system for proper instillation.
Unfortunatley, after there was a gas leak with our Navien system. Neil was able to get
James Farnworth
Neil from NJM was able to get my ac system up and running when others could not. He was honest with me right from the beginning and all costs were discussed before repairs began. Additionally, Neil spent time explaining to me how my system operates and the things I could do to help it run at peak performance. It was quite refreshing to experience a service technician who demonstrated the uppermost
Raul Chardon
Honest professional full of knowledge not BS. Takes pride in his craft and is a master of it.
Professional Window Installation & Replacement on Long Island
Improve your home’s comfort, efficiency, and curb appeal with NJM’s professional window installation and replacement services. We install high-quality, energy-efficient windows designed for long-term durability and flawless performance across Nassau and Suffolk County.
Energy-Efficient Windows • Precision Installation • Long-Lasting Results