Professional Door Installation & Replacement on Long Island
Enhance your home’s security, efficiency, and visual appeal with NJM’s licensed door installation and replacement services. We install high-quality exterior and interior doors designed for durability, weather protection, and smooth operation across Nassau and Suffolk County.
Precision Installation • Energy Efficiency • Long-Lasting Performance
Trusted Door Installation Professionals Serving Long Island
Whether you’re replacing an outdated entry door, upgrading your home’s interior doors, or installing new doors as part of a renovation or extension project, NJM Mechanical and Contracting delivers precise, code-compliant installations. With over 33 years of construction experience, we ensure every door is properly aligned, insulated, and secured for long-term performance.
Our team works with a variety of door types and provides solutions tailored to your home’s style, structure, and functional needs.
Professional installation of new interior and exterior doors with precise measurement, alignment, and finishing.
Upgrade old or damaged doors with modern, durable replacements designed to improve security, insulation, and appearance.
Expert adjustments and reframing to ensure new doors fit properly and operate smoothly within existing or modified openings.
Expert Door Installation Backed
by Over 33 Years of Experience
Why Choose NJM for Your Door Construction or Replacement Project
We are fully licensed and insured to perform residential and commercial door installations and replacements.
We are fully licensed and insured to perform residential and commercial door installations and replacements.
Our technicians ensure every door is properly anchored, sealed, and aligned for maximum security and longevity.
We offer installations that improve insulation, reduce drafts, and enhance indoor comfort.
Door installations include clean framing, trim work, and finishing that blend naturally with your home’s architecture.
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.
Door Frame & Structural Opening Inspection
Assessment of the existing frame, supports, and opening to ensure safe and proper installation.
Alignment & Swing Function Review
Ensuring the door opens, closes, and latches correctly with balanced weight and motion.
Weatherproofing & Seal Evaluation
Review of sealing, caulking, and insulation to prevent air or water infiltration.
Energy Efficiency Assessment
Verification of insulation, thermal protection, and door material performance.
Hardware & Lock Safety Check
Inspection of locks, hinges, handles, and hardware for smooth operation and security.
Long Island Code Compliance Review
Ensuring installations meet Nassau and Suffolk County building and safety standards.
Trusted Installation Expertise for Long Island Homes
Our WinOur Door Installation Safety & Inspection Services Include:dow Installation Safety & Inspection Services Include:
NJM provides detailed inspections and installation reviews to ensure every door meets safety, durability, and code-compliance standards.
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.