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Contracting

Interior & Exterior Door Services On Long Island

Entry doors, patio doors and interior doors installed and replaced by a licensed Long Island contractor. Serving homes across Nassau and Suffolk County.

ENTRY DOORSPATIO DOORSINTERIOR DOORSFREE ESTIMATES
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TASK 86/87 Certified
Navien NSS Certified
22+ YEARS ON LONG ISLAND

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LICENSED & INSURED · NASSAU & SUFFOLK
PLUMBING · HEATING · COOLING · CONTRACTING

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Contracting

Interior & Exterior Door Installation On Long Island

A door that sticks, drops, swings shut on its own or lets daylight through at the bottom is almost never a faulty door. It is an opening that is out of square, a frame that was not shimmed properly, or a house that has settled around a frame installed decades ago. Replacing the slab without addressing that just moves the problem to a newer door.

NJM installs and replaces interior and exterior doors for homes across Nassau and Suffolk County. Because we are a licensed general contractor rather than a door supplier, when an opening turns out to be out of square or a threshold has rotted, the repair is part of the job.

24/7 Emergency ServiceLicensed & Insured
  • Master PlumberLicensed to pull permits
  • TASK 86/87Certified for gas work
  • Navien NSSFactory-trained on tankless

22+ years on Long Island · Plumbing, heating, cooling, gas and contracting under one roof

What We Do

Door Services

Entry Doors

Front and side entry doors installed with the weatherproofing, threshold and sill detailing that keeps water out of the framing.

Patio & Sliding Doors

Sliding and hinged patio doors, including the sill and drainage detail that decides whether they leak in a driving rain.

Interior Doors

Room doors, closet doors and pocket doors, hung to swing and latch properly rather than approximately.

Storm Doors

Storm and screen doors fitted and adjusted so they close correctly and stay that way.

Frame & Threshold Repair

Rotted sills, damaged jambs and out-of-square openings put right rather than covered up.

Weatherproofing

Weatherstripping, sweeps and sealing — the difference between a door that looks right and one that stops draughts.

Hardware & Security

Locks, deadbolts, hinges and strike plates fitted so the security hardware is anchored into framing rather than trim.

Opening Modifications

Widening or altering an opening, with the framing and any header work handled and permitted.

Contracting — before you call

Two kinds of visit. You’ll know which before we come.

We don’t charge to quote a job. We do charge to find a problem nobody has identified yet. Which one you need — and what it costs — gets agreed on the phone, so nothing about the cost is a surprise on the doorstep.

Estimate visitNo charge

You already know what you want done

A boiler replaced, a bathroom rebuilt, a gas line run. We come out, look at the job and give you a number.

No obligation
Diagnostic visitQuoted on the call

Something has failed and nobody knows why

A licensed technician and the time to find what has actually gone wrong. One rate across plumbing, heating, cooling and gas, and one number to reach us on — there is no separate line to find at midnight. You get the figure before anyone is dispatched, and after-hours, weekend and holiday work is quoted the same way.

The rate you are told is the rate

You get the number on the phone, before anyone is dispatched, and it is what you are charged when the technician arrives. One rate across all four trades — plumbing, heating, cooling and gas.

What it pays for

A licensed, insured technician carrying the certifications the work needs, and the time to find what has actually failed — not a quick look and a guess.

Watch for the bait and switch

A call-out advertised at almost nothing gets recovered once someone is standing in your basement. Get the number before anyone travels — from us, or from anyone else you call — and hold them to it when they arrive.

Financing on larger jobs

A boiler that fails in January is not a purchase anyone planned. Financing is available on the big-ticket work, so a system replacement does not have to come out of savings in one go.

What it is normally used for

Boiler, furnace and water heater replacement, a full air conditioning system, a whole-house repipe, sewer and water main work, and larger contracting jobs — kitchens, bathrooms, dormers and extensions.

When to bring it up

At the estimate, before anything is scheduled. It is worth asking even if you think you will not need it, because knowing it is there changes what you are willing to consider fixing properly.

What it does not change

The price of the job. The quote is the quote whether you finance it or not — and on a straightforward repair it is usually not worth the paperwork. We will tell you which one you are looking at.

Financing provided throughSynchronyCredit is extended by Synchrony. Subject to credit approval.
Call 631-587-0085Not sure which one you need? Call and describe it — we will tell you before we book anything.
Diagnose First

The Door, The Frame And The Opening Are Three Different Things

Almost every door complaint gets described as a door problem, and most of them are not. Which of the three is actually wrong decides whether this is an afternoon or a replacement.

A door that sticks or will not latch is usually reporting on the house, not on itself. Doors are rigid; openings move. Seasonal humidity, a settling foundation, a header that has taken on load over the years — any of these will rack an opening slightly out of square, and the door that fitted it perfectly for thirty years now catches at one corner. Replacing the door in a racked opening buys you a new door that also sticks.

So the first question is which part has moved. If the gap around the door is even all the way round and it still binds, that is usually hinges or swelling. If the gap is wedge-shaped — tight at the top of the latch side and wide at the bottom, or the reverse — the opening is out of square and the fix is at the frame. If the door drags on the floor only in certain months, that is seasonal movement and it wants easing rather than replacing.

Daylight under an exterior door is almost never a reason to buy a door. It is a threshold, a sweep or a weatherstrip, all of which are cheap and quick, and all of which are the actual source of the draught people blame on the door itself. Where it does become a replacement conversation is when the bottom of the frame or the threshold has rotted, because at that point the door is no longer sitting on anything sound and no amount of weatherstrip fixes a soft frame.

We do all of it — adjust, rebuild, re-hang and replace — which is precisely why we have no reason to tell you a fifteen-minute job is a new door. Describe what it is doing and when, and we will tell you which of the three it is.

Quick Rules Of Thumb

  • Doors are rigid, openings move — a sticking door often means the opening
  • Even gap all round but binding: hinges or swelling
  • Wedge-shaped gap: the opening is out of square, fix the frame
  • Sticks only in certain months: seasonal, wants easing not replacing
  • Daylight underneath is a threshold or sweep, not usually a new door
  • A rotted frame bottom or threshold is where it does become a replacement
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Everything We Handle In Contracting

One licensed team, one number to call, across Nassau and Suffolk County.

Common Questions

Frequently Asked Questions

How do I tell whether it is the door or the frame?

Look at the gap around the door when it is nearly closed. If it is even the whole way round and the door still binds, it is usually hinges or the door itself having swollen. If the gap is wedge-shaped — tight at one corner and wide at the opposite one — the opening has gone out of square and the fix belongs at the frame rather than the door. And if it only happens in humid months, that is seasonal movement, which wants easing rather than replacing. Tell us which of those it is doing and we can usually tell you the answer on the phone.

Why would the opening move?

Because a house does. Seasonal humidity swells and shrinks timber, foundations settle over decades, and a header above an opening slowly takes on load. None of that is necessarily a structural alarm — it is normal in an older Long Island house — but it does mean a door that fitted perfectly for thirty years can start catching. The important part is that fitting a brand new door into an opening that has racked gives you a new door that also catches.

Is a draught under the door worth replacing the door for?

Almost never. That is a threshold, a sweep or a weatherstrip, all of which are inexpensive and quick, and all of which are the actual source of what people blame on the door. Where it genuinely becomes a replacement is when the bottom of the frame or the threshold itself has rotted — at that point the door is no longer sitting on anything sound and weatherstrip is covering up a problem rather than solving one. We will tell you honestly which one you have.

My door sticks and will not close properly. Does it need replacing?

Usually not. Sticking, dropping and self-swinging doors are nearly always an out-of-square opening, a frame that has moved, or hinges pulling out of the jamb — not a faulty door. Fitting a new door into the same opening tends to reproduce the problem. Worth diagnosing first, and it is often a much smaller job than replacement.

I can see daylight under my front door. Is that a big deal?

It is an air leak, and on an exterior door it is also a water and pest route. Often it is just a worn sweep or a threshold that needs adjusting, both of which are inexpensive. Sometimes it means the door or frame has dropped, which is a slightly larger fix. Either way it is worth dealing with before winter.

What is the difference between a slab and a pre-hung door?

A slab is the door alone, fitted into your existing frame — cheaper, but only sensible if the frame is square and sound. A pre-hung door comes in its own frame, so the whole assembly is replaced and can be set plumb and square. If the opening has moved, pre-hung is usually the answer that actually works.

Do exterior doors need permits?

Like-for-like replacement usually does not. Changing the size of an opening generally does, because it involves framing and possibly a header. We check the requirement for your Town or Village and handle it if needed.

What if the threshold or frame is rotted?

We repair it as part of the job. Rot at a threshold usually means water has been getting in for a while, so it is worth looking at what is underneath rather than fitting a new door over a soft sill. As a licensed contractor that work is ours, not a reason to stop.

Will a new entry door make the house warmer?

It will help if the current one leaks badly, but be realistic — a single door is a small part of a house’s total air leakage. If your goal is a warmer house rather than a better-looking entrance, there are usually cheaper places to start. We will say so rather than sell you a door to solve a draught problem.

Can you widen a doorway?

Often, yes, but it depends on whether the wall is load-bearing and what is running through it. Widening usually means a new header. We will establish that before promising anything, and handle the framing and permitting if it goes ahead.

Are estimates free?

Yes, free and with no obligation. Call 631-587-0085, or use the form and we will be in touch within 24 hours.

Service Area

Proudly Serving Long Island and Surrounding Areas.

Based in North Babylon, working across both counties — close enough to get there fast, local enough to know the housing stock and the permit offices.

Find Contracting Services Near You!

  • Long Island
  • Nassau County
  • Suffolk County

Towns We Serve

Proudly serving all of Nassau and Suffolk County, with deep local roots near our North Babylon home base.

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What Long Island Says

Reviews From Homes & Businesses We've Served

5 out of 5 stars

The experience I had with with NJM Mechanical & Contracting was a pleasant one. I had the pleasure of doing business with Neil. The work I had done was a basement entrance to my yard and it came out wonderful. The work performed as well as the communication is 10/10.

Nick UrziaJune 2026
Reviewed on Google

5 out of 5 stars

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 forward to working with the team again.

KrisApril 2025
Reviewed on Google

5 out of 5 stars

Bathroom remodel was completed to my complete satisfaction. Family & Friends enjoy experiencing their spa like bathroom grooming. Contractor was personable, professional, friendly, patient and knowledgeable.

Shirley KendallOctober 2024
Reviewed on Google

Read all 87 reviews from Google and Housecall Pro →

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