Mortised into door and frame
ANSI/BHMA A156.1 · UL 10C · NFPA 80
Maryland, DC & Northern Virginia
Concealed door hinges, also called invisible or hidden hinges, sit inside pockets cut into the door edge and the frame. When the door closes, no barrel, pin, or leaf shows on either side. Most models use steel links that fold and pivot as the door swings, and many open a full 180 degrees. Some newer designs add 3D adjustment, so a technician can fine-tune height, side, and depth without taking the door down. You will find them on flush doors, wall panels, and hidden rooms.
No knuckles or pins show when the door closes, keeping flush doors and wall panels seamless.
The hinge hides inside the door and frame, so nobody can pull pins or pry knuckles.
UL-listed models carry ratings from 20 minutes up to 3 hours when sized and installed correctly.
King Locksmith and Doors Inc. installs, repairs, and services commercial door hardware across Maryland, Washington DC, and Northern Virginia. We work with small businesses, government agencies, hospitals, hotels, schools, and large property management teams. Our trained technicians size each concealed hinge to the door, cut clean mortises, and adjust every door until it swings and latches just right. We also check fire-rated openings against the label, so your doors look sharp and pass every inspection.
Concealed hinges are less forgiving than standard butt hinges. The right model depends on door weight, thickness, fire rating, and frame type. Use these five quick checks before you order, cut, or install a hinge.
Door weight and height decide how many concealed hinges you need. A common maker rule calls for one hinge per 20 inches of door height or one per 60 pounds, whichever gives more.
That means a standard 7-foot door often needs four or five concealed hinges, not three. Too few hinges is one of the most common causes of early sag. Weigh the door or check the door schedule before you pick a hinge model.
Every concealed hinge model has a minimum door thickness. Some popular full-size models need a 2-inch door, while many commercial doors are only 1-3/4 inches thick. Always check the cut sheet.
If the hinge body is too deep for the door, the mortise weakens the edge and can split wood or crush a metal skin. Measure the door edge and the frame face first. Then match the hinge model to both before you cut anything.
A concealed hinge on a fire door must carry its own UL listing for that door type and rating. Listed models range from 20 minutes up to 3 hours, depending on the maker and model.
The hinge count, screws, and door construction must also match the listing. NFPA 80 calls for yearly fire door inspections, so a wrong hinge can fail you later. Keep the hinge cut sheet with your fire door records for inspectors.
Wood doors need a solid core or solid blocking where each hinge goes. Never mount into hollow core. Hollow metal doors and frames need reinforcement or a factory prep sized for the hinge body.
Aluminum and stile-and-rail doors often leave too little room for a concealed hinge pocket. In those cases, a pivot or continuous hinge may work better. A site survey confirms what your doors and frames can safely hold before any work starts.
Busy doors in hospitals, schools, and hotels need heavy-duty concealed hinges with strong steel links. Models with 3D adjustment let a technician correct small shifts later without removing the door.
You can also add invisible closer hinges, which pull the door shut quietly with no closer arm in sight. Many makers call for one closer hinge per 55 pounds of door weight. Set the closing force so the door still meets ADA opening force limits.
Butt hinges are the most common hinge on commercial doors. Here is how concealed door hinges compare when appearance, security, and safety matter most in your building and daily operations.
Consideration
Concealed Door Hinges
Butt Hinges
Fully hidden when the door is closed
Knuckles and pins stay visible at all times
No exposed pins to pull or cut
Outswing doors expose pins that need NRP studs
Pivot stays inside the hinge during travel
Open knuckle gap can pinch small fingers
Nothing exposed to kick, pry, or deface
Exposed barrels can be pried or damaged
Smooth door edge with no knuckle crevices
Knuckle seams trap dust, grime, and germs
Concealed hinges hide their problems until the door starts to drag or drop. These are the failures we see most often on commercial doors across Maryland, DC, and Northern Virginia.
We carefully size, mortise, and mount concealed hinges on new or existing wood and hollow metal doors.
We swap worn, noisy, or undersized hinges for stronger models that match your door weight and thickness.
We correct sagging, rubbing, and binding doors by adjusting, shimming, or adding hinges where the load demands.
We match concealed hinges to the fire door label so your openings pass NFPA 80 yearly inspections.
We install invisible closer hinges that shut doors smoothly without a visible closer arm on either side.
We install power transfer concealed hinges that route low-voltage wiring to electrified locks and access control systems.
Talk with our team today about concealed door hinges for your building. We serve Maryland, Washington DC, and Northern Virginia.
