Sizing a Door Closer: Power Sizes 1 to 6 and the 5 lb ADA Limit
, by United Doors and Locks, 4 min reading time
Closer power size comes from door width. Then the ADA opening-force and closing-speed limits have to be met at the same time. How to do both.
A door closer has to do two things that pull against each other. It must generate enough force to pull the door shut and latch it, and it must be light enough for a person with limited strength to open. Sizing is the process of satisfying both, and it is where most closer complaints originate — a door that slams, a door that does not latch, or a door nobody can open.
Power size comes from door width
ANSI/BHMA A156.4 defines six power sizes. The governing dimension is the door's width, because width sets the leverage the closer has to overcome:
| Power size | Maximum door width | Typical application |
|---|---|---|
| 1 | 24 in | Light interior, cupboard doors |
| 2 | 30 in | Small interior doors |
| 3 | 36 in | Standard interior commercial door |
| 4 | 42 in | Standard exterior, wide interior |
| 5 | 48 in | Wide or heavy exterior doors |
| 6 | 54 in | Very wide or very heavy doors |
A 36-inch interior door is a size 3. Move that same door outside and you should generally size up one, because an exterior closer is fighting wind pressure and stack effect in a way an interior closer never is.
Why adjustable closers are worth the money
A fixed-size closer commits you to a decision made before the door was hung. An adjustable spring closer covers a range of sizes and can be tuned on site once the real conditions — the frame, the weatherstripping, the building's air pressure — are known.
The 600 Series is supplied in 1–4 and 3–6 spring ranges, which between them cover almost any commercial door. For maximum-duty openings, the cast steel 900 Series is a Grade 1 closer with backcheck and a parallel arm bracket. The 800 Series sits between them.
The ADA limits
Two requirements apply, and they are separate.
Opening force. Interior doors that are not fire doors must open with no more than 5 pounds of force. The Americans with Disabilities Act and ICC A117.1 both set this figure, and it is measured at the latch edge with a door pressure gauge. There is no ADA opening-force limit for exterior doors, because they have to resist weather, but many local authorities set one anyway — check before assuming you are unconstrained.
Closing speed. From an open position of 90 degrees, the door must take at least 5 seconds to reach 12 degrees from the latch. From 12 degrees to fully closed, at least 1.5 seconds. The first figure gives a slower-moving person time to pass through; the second stops the door from catching a hand or a heel in the final few inches.
Resolving the conflict
The pressure between the two requirements is real: a size 5 spring on a heavy exterior door may exceed 5 pounds on the interior side of a vestibule. The fixes, in the order to try them:
- Reduce the spring power to the lowest setting that still latches the door reliably. Test it, do not assume it.
- Check the door before blaming the closer. Binding hinges, a dragging bottom seal, tight weatherstripping, and a misaligned strike all add opening force. An overtight seal can account for several pounds on its own.
- Adjust the latch speed up while keeping the main sweep speed slow, so the door has the momentum to latch without moving fast through the doorway.
- Move to a power operator where the door genuinely cannot meet both requirements — a heavy exterior entrance on an accessible route, for example. This is a legitimate outcome, not a failure of sizing.
Fire doors are not exempt
A fire door must close from any open position and latch positively, every time. That requirement outranks the 5 pound opening force target, which is why fire doors are excluded from it. Never reduce a closer on a fire door to the point where it no longer latches, and never fit a hold-open device that is not tied to the fire alarm.
Backcheck and delayed action
Backcheck resists the door in the last part of its opening arc, so a gust of wind or a shove does not throw it against the wall and tear out the closer. Specify it on every exterior door and any interior door that opens against a wall. The 900 Series includes it.
Delayed action holds the door open for several seconds before starting to close. It is worth specifying at accessible entrances, on doors used with trolleys and beds, and anywhere a slow-moving person needs more than the minimum. It is a separate valve, not the same as slowing the sweep.
Before you order
You need door width, door weight, interior or exterior, whether the assembly is fire rated, which side the closer can be mounted on, and whether the opening is on an accessible route. With those six facts a closer can be specified correctly the first time.
Send us the door schedule with widths and locations and we will size the closers against it, including arm type and mounting.