Why Does My Commercial Door Slam Shut? 7 Causes & Fixes

A commercial door that slams is more than an annoyance. It breaks glass, loosens frames, shakes hardware apart and catches fingers and heels. It is also one of the easiest door problems to diagnose, because nine times in ten the cause is the closer: the arm-and-body unit at the top of the door that is supposed to bring it shut under control.

We adjust and replace closers every week in Saskatoon and Regina. These are the seven causes we find, in the order we check them.

How a door closer controls the door

A closer is a spring and a piston in a sealed body of hydraulic fluid. Opening the door winds the spring. When you let go the spring pushes the door shut, and the fluid has to squeeze through small adjustable valves to let it move. The valves are what turn a spring-loaded slam into a controlled close.

Most commercial closers have three or four adjustments:

• Sweep speed: from fully open to the last few inches
• Latch speed: the last few inches, where the door meets the frame
• Back-check: resistance as the door opens past about 70 degrees
• Spring power: how hard the spring pushes, on adjustable-size closers

A slam means one of those is set wrong, or the fluid that makes them work is no longer there.

1. The sweep or latch speed is set too fast

This is the first thing to check and the cheapest fix. Someone turned a valve out to get a door to latch, or the closer was never set up after installation.

Open the door to 90 degrees, let go and watch. If it rushes the whole way, slow the sweep. If it travels calmly and then snaps shut at the end, slow the latch speed. Turn the valve clockwise an eighth of a turn, test, and repeat. Small turns matter: a quarter turn can double the closing time.

A good target is a door that takes five seconds or more to close from 90 degrees and lands with a firm click, not a bang. Never back a valve all the way out. On many closers that lets the fluid out, and the closer is finished. Our door closers page covers the adjustments in more detail.

2. The closer is leaking

Look at the closer body, the arm and the top of the door below it. Oil, a dark stain or a drip line means the seals have failed. With the fluid gone there is nothing to meter the spring, so the door closes at full force no matter where the valves are set.

A leaking closer cannot be topped up or resealed on the door. It is replaced. If turning the valves changes nothing, assume the fluid is gone even if you cannot see the leak.

3. The season changed and the closer did not

Closer fluid thickens in the cold and thins in the heat. A closer adjusted in January to get a stiff door to latch will close much harder in July. The reverse happens in the fall, which is why the same door slams in summer and will not latch in winter.

Saskatchewan swings from plus thirty to minus thirty, and exterior doors feel all of it. Plan on adjusting exterior closers in spring and fall. Closers with all-weather fluid hold their settings better and are worth specifying on any exterior door. Our guide to winter-proofing commercial doors covers the cold half of the problem.

4. The spring power is too high

Spring power is the size of the closer. It needs to be strong enough to close and latch the door against wind, seals and air pressure, and no stronger. A closer that is oversized or cranked up to its highest setting takes more effort to open and hits harder when it closes. The valves can slow it down, but they are fighting the spring the whole way.

This usually shows up as a door that is both hard to open and hard on the frame. Reducing the spring power, or fitting a closer sized for the door, fixes both. It also matters for accessibility: a door that takes too much force to open is a barrier, and an automatic door operator is often the better answer on a main entrance.

5. Wind or building pressure is driving the door

If the door only slams on windy days, or only when the HVAC is running, the closer may be fine. Wind catches an outswinging door like a sail. Negative building pressure pulls a door shut; positive pressure pushes it. Stairwell and vestibule doors are the usual victims.

The closer can be set for these conditions, within limits. Back-check stops wind from ripping the door open and bending the arm. A heavier-duty closer holds its speed against gusts better. Where wind is constant, a closer with a stop arm or an overhead stop protects the door and the wall.

6. The arm is loose, bent or installed wrong

The arm connects the closer to the frame. If the screws at the shoe have pulled out, the arm joint is loose, or the arm was bent by a door that was forced open, the closer loses its geometry and its control. A closer mounted in the wrong position for its arm type does the same thing from day one.

Look for an arm that moves before the door does, screws backing out of the frame, or an arm that is not straight. Fasteners can be replaced with through-bolts. Bent arms are replaced, and most manufacturers sell them separately from the body. This is routine door hardware repair.

7. The closer is worn out or wrong for the door

Closers are rated by cycles. A light-duty closer on a busy entrance will wear out in a couple of years: it gets harder to adjust, stops holding its settings and eventually leaks. A heavy door, a wide door or an exterior door with a residential-grade closer on it will slam because the closer was never able to control it.

If the closer has been adjusted more than once in a year and keeps drifting, it is at the end of its life. Replacing it with a commercial grade closer sized for the door, the traffic and the exposure is cheaper than the glass, hinges and frame repairs that a slamming door causes.

What slamming does to the rest of the door

A door that slams a few hundred times a day is hammering everything attached to it. We see the same damage repeatedly:

• Hinge screws loosen and the door sags
• Latches and strikes wear until the door will not stay shut
• Exit devices shake out of adjustment
• Glass kits and storefront glazing crack
• Frame anchors loosen in the wall
• Electric strikes and access control hardware fail early

Most of those repairs cost more than a closer.

Fix it yourself or call?

Adjusting sweep and latch speed in small steps is safe to do yourself with the right size of hex key or screwdriver. Stop and call if you see oil, if the valves make no difference, if the arm is bent, or if the door is a fire door. Fire doors must close and latch on their own every time, and the closer on a fire door has to be a listed one. Guessing at it is not worth the risk.

Need a door closer adjusted or replaced in Saskatoon or Regina?

Prestige Lock & Door provides fast, professional locksmith and door hardware service across Saskatchewan. Most slamming doors are fixed in one visit.

• Closer adjustment and seasonal service: set for the door and the weather
• Closer replacement: commercial grade, sized for the door and the traffic
• Hinge, frame and latch repair: the damage a slamming door leaves behind
• Two branches: Saskatoon (306) 880-0307 and Regina (306) 552-8646
• Sales, service and installation under one roof: see the brands we carry

Contact us or book a service call and we will get the door closing quietly.

Related articles

• Why is my commercial door so hard to open?: closer power, air pressure and binding latches
• Why won’t my commercial door close or latch?: the opposite problem, and its nine causes
• Winter-proofing commercial doors: why doors set in October fail in January
• Access control for small business: the hardware a slamming door wears out first