One stuck unit door, or a row that is due

Why does a storage unit roll-up door get hard to lift?

Almost always one of three things. The counterbalance spring inside the barrel above the opening has lost tension, the guides on either side have packed up with grit, or the bottom bar has been bent and is dragging. A properly tensioned unit door lifts with one hand and stays where it is let go. This is routine commercial garage door repair, and the three causes feel different at the handle.

• Lost spring tension makes the door heavy from the first foot and stays heavy all the way up, then drifts back down when released at chest height. Both sides move evenly. Nothing grinds.
• Grit in the guides. The door starts easy, then drags or stutters at the same height every time, and usually worse on one side. After a dry August with gravel drive aisles, this is the common one.
• A bent bottom bar shows at the floor. The bar sits out of line with the slab, one end rides in its guide at an angle, and the door fights hardest in the first few inches.

A tenant will describe all three the same way (“it’s stuck”). The difference matters because only one of them is a spring job.

Can the spring tension on a roll-up door be adjusted instead of replaced?

Usually, yes. Unit door springs relax over years of cycles, and winding tension back into the barrel is a normal service item on these doors. A spring that has broken is a replacement, not an adjustment. Neither one is a job for a manager or a tenant, because the barrel holds the load that keeps the curtain from dropping.

The tell that separates the two cases is how the door fails. A tired spring gives a door that gets gradually heavier over a season. A broken one gives a door that was fine on Tuesday and is dead weight on Wednesday, sometimes with a sharp crack from inside the hood that somebody on the property heard.

What looks like a small adjustment is the risky part. The tension fitting sits at one end of the barrel with the whole spring wound up behind it. Turning or loosening anything at that end releases that tension into whatever is holding it, and on a unit door that is often a hand. Leave the hood covers on. Tape a note to the handle, and keep the unit locked or closed off until someone with the right bars and fittings sets it.

What happens when a vehicle clips a unit door?

Drive aisles on a storage row are tight, and the doors at the end of a building take the most hits. A trailer swinging wide around the corner, or a pickup backing into an end unit, catches the bottom bar first because it sits at bumper height. What is left depends on how far the impact went.

What got hit	What it usually looks like	What usually happens to it
Bottom bar only	Bar bowed in, door still closes but gaps at one end	Straightened or replaced as a part, curtain left alone
Bottom bar and guide	Guide leaning out of plumb, door binds near the floor	Guide reset or replaced, bar replaced
Curtain	A crease running across the corrugations, door stops at the crease	Damaged section replaced or the curtain replaced, depending on the door

The most expensive version of this is often self-inflicted. A door with a bent bar that somebody forces up by hand, or leans on to get it closed, drags the curtain through a guide it no longer fits. Every pass creases the sheet a little more. A bar can be swapped. A curtain that has been walked up past a bad guide a dozen times is often a whole new curtain.

If a door got clipped, leave it where it stopped and let the tenant know it is out of service. The photos you take for your own records and for the driver’s insurer are worth more before anyone moves it.

Why does a unit door drag or catch on one side?

A unit door jams when something in the guide channel stops the curtain edge from sliding. The usual list is grit and debris packed into the channel, a guide bolt that has worked loose and let the guide shift, or a curtain that has racked to one side so one edge rides deeper than the other. Where it jams, and on which side, tells most of it.

Look, but do not pry. A manager’s check takes about two minutes per door:

1. Stand back and look at the door closed. Is the bottom bar level with the slab, or lower at one end?
2. Look down each guide from outside. Gravel kicked up from the drive aisle and packing tape or cardboard scraps from move-outs are the common finds.
3. Check the guide bolts at the wall with your eyes, not a wrench. A gap behind a guide, or a bolt head standing proud, means that guide has moved.
4. Lift the door a foot by hand and watch the bottom bar. If it comes up tilted instead of level, the curtain has racked.

Clearing loose debris you can reach from outside the guide is fine. A screwdriver or a pry bar in the channel is how guides get sprung and curtain edges get torn, and it turns a service visit into a parts order.

Winter adds one more. Slush that runs into the foot of a guide can freeze there overnight and lock the ends of the bottom bar in the channel. It shows up on the north-facing side of a building, where the sun never reaches the doors in January, and it thaws on its own in a day or two of milder weather. Keeping the guide feet cleared of packed snow prevents most of it. Forcing the door against it bends the bar.

What about a latch or lock hasp that will not throw?

Small parts, and they cost the facility more than their size suggests, because a unit whose latch will not engage cannot be left occupied or rented out. The two usual causes are a latch bent by a cut lock or a pry, and a latch that no longer meets its keeper because the curtain has sagged or racked.

The first shows up after a lock cut, whether that was an overlock removal, a lost key or a break-in. The slide bar or hasp gets levered or struck, bends out of line, and the new lock will not go through. It is a straightforward part replacement.

The second case is the one worth noticing. If a latch that used to throw cleanly now needs the door pushed down hard, or lifted slightly, before it lines up, the latch itself is probably fine. The door has moved. Lost spring tension lets the curtain settle lower, and a racked curtain brings one side down before the other. Replacing the latch on that door fixes nothing for long. Setting the tension or squaring the curtain fixes the latch as a side effect.

Should the whole row get serviced at once or one door at a time?

One door at a time works for true one-offs, like a clipped end unit or a cut latch. When the calls start coming for the same kinds of trouble on the same building, a scheduled row visit is the better buy. The tech works down the row checking every door’s spring tension, guides, bottom bar and latch, and sets the ones that are drifting before a tenant finds them.

The pattern that says it is time for the row is easy to spot from the office. Three or four calls in a season, all on one building, all variations on hard to lift or will not lock, means the doors on that building are aging together. They went in at the same time and have weathered from the same side since, so the doors that have not been called in yet are usually a season or two behind the ones that have.

A row visit also changes when the work happens. Per-door calls come in whenever a tenant complains, often on a weekend. A scheduled visit can run on a weekday morning with the rented units that need access sorted out ahead of time, and the commercial overhead door service page covers the off-hours scheduling and the twice-a-year preventive service that keeps a building’s doors inside their wear limits. Work is priced before the visit either way, so per-door calls and a row visit can be compared on paper first.

Keep a short log either way, with the unit number, the date and what the door did (heavy, dragging, would not latch). A unit that shows up twice in a year, or a building with three entries in one season, is the one to put on the row visit first.