Regular Arm, Parallel Arm, Top Jamb: Mounting a Door Closer Three Ways
, by United Doors and Locks, 6 min reading time
Regular arm is the most efficient, parallel arm is the most protected, top jamb is for doors that cannot carry a closer. How to pick, and when to size up.
A door closer can be mounted three ways, and the choice is not cosmetic. It changes how much of the closer's power reaches the door, how exposed the arm is to abuse, and in some cases whether the closer will fit at all.
First, know your two sides
Every closer instruction sheet uses these terms, so it is worth fixing them before anything else.
The pull side is the side the door opens toward you — you pull to open. The push side is the side the door opens away from you. Standing in a corridor at an office door that swings into the office, you are on the push side.
Regular arm
Closer body on the door, pull side. Arm projects out to the frame.
This is the mechanically efficient mounting. The arm meets the door at close to a right angle through most of the swing, so the closer's spring force translates into closing force with the least loss. For a given power size you get the most useful work out of a regular arm mounting.
The cost is exposure. The arm stands off the frame and is the first thing a trolley, a wheelchair footplate, or a shoulder makes contact with. On a school corridor it is the part that gets bent. Regular arm mountings also put the closer body on the corridor side of an office door, which architects tend to object to.
Use it on interior doors in low-abuse areas where the pull side is the protected side.
Parallel arm
Closer body on the door, push side. Arm folds back parallel to the door face.
This is the commercial default, and for good reason. The arm tucks against the door instead of projecting, which puts it out of the way of traffic and out of reach of casual abuse. It allows the door to swing to 180 degrees where the wall permits, and it keeps the closer on the room side of an office door rather than in the corridor.
It needs a bracket — a shoe fixed to the underside of the frame head — which is why closers such as the 900 Series are supplied with a parallel arm bracket as standard.
The trade-off is efficiency. Because the arm works at a less favourable angle, a parallel arm mounting delivers roughly 10 to 15 percent less closing force than the same closer on a regular arm. Size up one power size when mounting parallel arm on a door that is marginal, or use an adjustable closer such as the 600 Series and set the spring accordingly.
Parallel arm is also what you use on an outswing exterior door, because it puts the closer inside where the weather cannot reach it.
Top jamb
Closer body on the frame face, push side. Arm reaches down to the door.
Top jamb exists for doors that cannot carry a closer. The obvious cases are aluminium storefront doors with narrow top rails, all-glass doors, and doors where the top rail is too shallow to take the mounting screws. It is also useful on a door face that has to stay clear for a push plate or signage.
Efficiency sits between regular and parallel arm. The practical constraints are on the frame side: you need enough flat frame face above the door to mount the body, and the frame reveal has to fall within the closer's range. A deep reveal may require a drop plate or a different arm entirely. Measure the reveal before ordering.
Choosing quickly
| Situation | Mounting |
|---|---|
| Interior door, low abuse, pull side protected | Regular arm |
| Corridor, school, hospital, retail | Parallel arm |
| Outswing exterior door | Parallel arm, closer inside |
| Aluminium storefront or narrow top rail | Top jamb |
| Glass door with no rail to fix to | Top jamb, or a floor closer |
| Door must open past 100 degrees | Parallel arm |
Two accessories that solve real problems
Drop plate. Fills the gap when the door's top rail is too narrow for the closer body but not narrow enough to force a top jamb mounting. Cheap, and it saves a return.
Stop arm or cush arm. A parallel arm variant with a built-in stop, so the arm limits how far the door opens instead of relying on a separate wall or floor stop. Useful where the door would otherwise swing into a wall and there is nowhere to fit a stop. It transfers the impact load into the closer and the frame, so specify a heavy duty closer such as the 900 Series when you use one.
Sex nuts on hollow metal doors
Screws into a hollow metal door face pull out under a closer's repeated load. Through-bolts — sex nuts — clamp the closer through the door instead of relying on the skin. The 900 Series ships with them. On any hollow metal door with a closer, use them; a closer that tears out of a door face takes the door skin with it.
Before you order
Confirm which side the closer can be mounted on, the top rail height, the frame reveal, the door width, and whether the door needs to open past 100 degrees. Send us the openings and we will specify the closer, arm, and any bracket together, so the parts arrive as one set.