Can you replace a slat on a roll up door?

Why one slat can be replaced

A rolling steel door has no panels or hinges. Its curtain is a stack of narrow steel slats, each one hooked into the slat above and below it along a curled edge, and the whole curtain coils around a barrel above the opening. Because the slats are joined only by those interlocks, a slat can slide sideways out of the curtain once its ends are free. That is what makes a repair possible: the damaged part comes out and a new piece goes in, while the barrel, springs, guides and the rest of the curtain stay where they are.

DASMA, the door and operator makers' association, puts it this way in its sheet on component substitution: unlike sectional doors with sections hinged together, rolling doors rely on the interlocking connections of the slats to hold together. So the slat joint is both what lets the repair happen and the thing the repair must get right.

Replace the slat or the curtain?

What you see	What it usually means	Usual fix
A shallow dent; the door still runs smoothly	Cosmetic damage	Often nothing yet; watch that it does not catch
A kinked or creased slat that catches in the coil or the guides	The slat can no longer flex as the curtain rolls	Replace that slat and any bent with it
Slats pulled apart at a joint, or a torn slat	The interlock has failed	Replace the damaged slats
Slat ends bent, endlocks or windlocks missing	The curtain can shift sideways or leave its guides	Replace the endlocks or windlocks, and the slat if its end is bent
A bent bottom bar	The bottom bar is its own part, not a slat	Straighten or replace the bottom bar
Damage across much of the curtain, heavy rust, or slats no longer made	Too many slats, or no matching parts	A new curtain, or a new door

How a slat replacement is done

1. Make the door safe. The curtain is closed and the motor is switched off. The springs in the barrel stay under tension the whole time, so they are not touched for a slat repair.
2. Free the slat ends. The endlocks or windlocks on the damaged slats are taken off. These fittings sit on the slat ends, stop the slats from sliding sideways and keep the curtain in its guides.
3. Slide the slats out. With the ends free, the damaged slat slides out of its neighbors along the interlock, together with any slat whose joint bent with it.
4. Slide the new slats in. The new slats, cut to the same length, slide into the open joints.
5. Refit the ends and test. The endlocks or windlocks go back on so the curtain runs straight, then the door is run up and down to check that it coils cleanly and does not rub the guides, the hood or the header.

On a closed door the damaged slats are often low on the curtain, where forklifts, carts and bumpers hit. Slats higher up may mean partly opening the door or taking the hood off to reach them, which is part of why this is a job for a technician.

Why the slat has to match

DASMA's warning is that slats with the same general shape and size may or may not be interchangeable, because each rolling door maker may use its own slat design for the interlock, and slats that fit badly can stop the door from working properly. A slat from another door can look right on the bench and then bind in the coil, pull apart at the joint or sit proud in the guides.

Before parts are ordered, the slat is identified by:

• Profile. Flat and curved slats are different parts, and insulated slats with a foam core and a back skin are different again. See curtain slat for the common profiles.
• Height. How tall each slat is from joint to joint, often between 2 and 3 inches.
• Gauge. How thick the steel is. A thinner slat in a heavier curtain will dent and pull apart first.
• Length. The slat is cut to the curtain's width, measured without the endlocks.
• The maker. The door's maker and model are often on a label on the guide or the bracket at the top of the door.

Doors with extra rules

Fire-rated rolling doors. DASMA notes that under NFPA 80, a fire-rated rolling door must be repaired with parts from the manufacturer of that door. A generic slat is not allowed on a fire door, even if it fits. Fire doors also have their own inspection and drop test rules, which DASMA covers in its TDS 271, so tell the technician up front that the door is fire rated.

Wind-rated doors. On a door built to a wind rating, DASMA says the slats, windlocks, rivets, bottom bar and guides all count toward that rating, and replacements should be worked out with the door's maker so the door still holds.

Can I replace a roll up door slat myself?

Sliding a slat out sounds simple, and on a small, light storage unit door with an open spring it sometimes is. On a commercial rolling steel door it is not a good DIY job. The curtain is heavy, the springs in the barrel are under tension at all times, and DASMA's guidance for building staff is that only a trained door technician should make repairs and adjustments, because a mistake can cause severe injury. A slat that is the wrong profile also tends to show up only once the door is coiling, when the curtain binds.

What building staff can safely do is look. DASMA's checklist for facility managers asks that the curtain and bottom bar not be bent or damaged, not bind in the guides and not rub the wall above the opening, and that endlocks and windlocks not be loose or missing. If any of those fail, stop running the door and call for service. Running a door with a kinked slat can tear the curtain or pull it out of a guide.

Common questions

Can you fix a dented roll up door without replacing it?

Usually, yes. A dent that does not catch can often be left alone. A slat that is kinked enough to jam the coil or the guides is replaced, along with the slats bent beside it, and the rest of the curtain stays.

Can you replace the bottom slat on a roll up door?

Yes. The lowest slats take most of the hits. Note that the heavy piece at the very bottom is the bottom bar, a separate part that carries the seal and any safety edge, and it is repaired or replaced on its own.

How many slats need replacing?

Every slat that is kinked enough to catch in the coil or the guides, plus any whose joints bent with it. A hit from a forklift often bends two or three slats, not one.

Does a roll up door off its guides mean the slats are damaged?

Not always. A curtain often leaves a guide because an endlock or windlock broke or a guide was bent. See what to do when a commercial door is off track.

Is this the same as replacing a garage door panel?

The idea is the same, swapping the damaged part and keeping the rest of the door, but the parts are different. A home sectional door has hinged panels on rollers, not interlocking slats. See garage door panel replacement for that door.

How G Brothers helps

G Brothers repairs roll up and rolling steel doors across the Denver metro, on storefronts, warehouses, loading docks and self-storage buildings. That includes replacing bent, torn or separated slats, endlocks and windlocks, bottom bars and guides, and straightening curtains that bind in the coil, and we service and repair fire-rated rolling doors too. The slat is measured before parts are ordered so the new ones match the old. See roll up and rolling steel door repair and storage unit door repair, call (720) 421-6489 or request a free estimate.

If the door is also loud when it runs, see what the noise from a roll up door means.

Sources

• DASMA, TDS 287: Rolling Door Component Substitution
• DASMA, TDS 269: Rolling Door Performance Evaluation by a Facility Manager or a Building Superintendent
• DASMA, TDS 270: Recommended Rolling Door Maintenance Practices for Building Maintenance Supervisors