Troubleshooting by symptom · Rolling Shutter Guide
Why does light show at the top of my rolling shutter when it’s closed?
Insulated slats have small vent slots in their hinges that pass light until the curtain is fully down and the slats press together. Light at the top of a closed shutter points to a curtain that is not settling: the down limit stops it short, or the curtain is slightly too tall, so the top slats hang at an angle.
Key facts
- Venting is standard on Roll-A-Shield's foam-filled slats: light and air pass through the hinges while the shutter is part-way down, and the slats close together for blackout once it is fully down. Roll-A-Shield data
- If a curtain is too tall for the opening, the top one or two slats do not settle when it closes, leaving visible light slits and a settling noise; it is worse on wide units where the axle sags. Roll-A-Shield data
- On 38 mm mini insulated shutters, the configurator builds the top 3 slats without vent slots by default, so a curtain that is not pressed all the way down does not leak light at the very top. Roll-A-Shield data
- The 38 mm mini insulated slat can be ordered non-vented for blackout at every position; the 55 mm standard insulated slat is always vented. Roll-A-Shield data
- Spring-operated shutters are built non-vented by default, because the spring can pull up on a closed curtain and open small gaps between the slats. Roll-A-Shield data
Applies to: Rolling shutters (roll-down security shutters) with insulated (foam-filled) or single-wall aluminum slats, manual or motorized; Roll-A-Shield 38 mm mini and 55 mm standard insulated shutters, and 63 mm single-wall and perforated shutters.
The shutter is down, but a line of light shows across the top slats. On an insulated shutter the slats are designed to pass light until they press together, so the question is why the curtain is not settling fully. The cause decides the fix.
Symptom, likely cause, what to do
| What you see | Likely cause | What to do |
|---|---|---|
| Light through the slats, and the curtain did not reach the sill | Down limit stops short, so the vents stay open | Reset the down limit |
| Light slits across the top one or two slats, often with a bang as it closes | Curtain slightly too tall; top slats hang at an angle | Call; it is a curtain fit problem |
| Same, mainly on a very wide shutter | Axle sag adds to the angle at the top | Call; box and axle sizing |
| Light between slats on a spring shutter | Spring pulling up on the closed curtain | See spring shutter problems |
| Light under the bottom slat | Curtain short of the sill, or seal too small | Check the down limit; ask about a larger seal |
| Pinpoints of light through every slat, even fully closed | Perforated slats | Normal; perforated slats are see-through by design |
Why do insulated slats let light through at all?
Because they are vented. Venting is a dashed line of small punched holes in the hinge area of each slat. With the shutter part-way down the hinges are open, so light and a breeze come through; once the shutter is fully closed, gravity pulls the slats together and the curtain blocks light, most rain and the elements. Venting is standard on both of Roll-A-Shield's foam-filled slats, the 38 mm mini and the 55 mm standard.
So light through the slats of a "closed" shutter means the slats are not pressed together, and the first suspect is a curtain that is not getting all the way down.
Is my shutter going all the way down?
Check it with the box cover off if you can. The bottom limit is right when the entire roll of slats is off the axle and the hanging straps have pushed the top slat toward the box. If the curtain stops short of that, the vents near the top stay open. Resetting the down limit is an owner job on a remote-operated shutter; see Shutter stops too high, too low, or leaves a gap.
Limits that were right and then changed can come from slack in the slat roll winding up egg-shaped; run the curtain fully down so it picks up evenly, then reset.
What if it is fully down and still shows light at the top?
One documented cause is a curtain that is a little too tall for the opening. At full extension the top one or two slats do not settle correctly, because of the angle they come down at, and that leaves visible light slits and a settling or banging noise. It is worse on large shutters, where a wide axle sags and adds to the angle. A curtain built too tall also leaves the hanging straps nearly fully extended.
This is a fit issue in the curtain or the axle, not an adjustment, so call (480) 921-0200. Roll-A-Shield sizes the box to the curtain height, and steps the box up one size when the axle is sag-critical.
Roll-A-Shield builds mini insulated curtains with the top 3 slats non-vented by default, so that a curtain which is not pressed all the way down still does not leak light at the very top.
Which slats give full blackout?
| Slat | Vented? | Light when fully closed |
|---|---|---|
| 38 mm mini insulated | Vented by default, or non-vented to order | Blackout; non-vented also blacks out part-way down |
| 55 mm standard insulated | Always vented | Blackout once fully closed |
| 63 mm single-wall | Not vented | Solid slat |
| 63 mm single-wall perforated | Perforated holes | See-through by design; no blackout |
Spring-operated shutters are built non-vented by default, because the spring can pull up on a closed curtain and open small gaps between the slats.
Roll-A-Shield's installation guides call for a U-channel along the bottom of the opening when there is no flat surface for the shutter to rest on, or when extra room darkening is wanted; after installation the perimeter of the shutter is sealed with caulk. See What is a U-channel?.
What next
If you are choosing slats for a bedroom or a home theater, ask for non-vented mini slats on a quote. For a curtain that is too tall or a sagging axle, call (480) 921-0200; in metro Phoenix, Roll-A-Shield repairs rolling shutters of any brand.
Frequently asked questions
Do rolling shutters give full blackout?
Vented insulated slats give blackout once the shutter is fully closed and the slats press together. For darkness at every position, the 38 mm mini slat can be ordered non-vented. Perforated single-wall slats are see-through by design and never black out.
Can a shutter with extra slats be pushed up from outside?
In Roll-A-Shield's experience with standard shutters resting in a U-channel, the curtain is too heavy to push up from outside, so it is better to have enough slats than a too-tall gap.
Why is there a gap under the bottom slat?
First check the down limit: the curtain should run all the way down. On mini spring-assist shutters, Roll-A-Shield has closed a light gap under the bottom slat by fitting a larger seal.
Do perforated slats let light through when closed?
Yes. Perforation, offered only on the 63 mm single-wall slat, lets you see through even when the shutter is fully closed, so it gives constant visibility and no blackout.
Parts and next step
Need a part or a hand?
Replacement motors, remotes, straps, slats and hardware ship from our Tempe, Arizona factory. Phoenix-area owners can book a service visit; everywhere else, our technicians help by phone. Call (480) 921-0200; the factory answers technical questions for any rolling shutter, not only ours.