Sizing and engineering · Rolling Shutter Guide
What size box does a rolling shutter need, how far does it stick out, and how much headroom?
Roll-A-Shield boxes run from 6.5 to 12 in and are chosen by slat type and curtain height (the clear opening height plus 2 in). Each box is roughly square, so it sticks out from the wall about as far as it is tall. On a surface mount, allow the box height plus about 2 in of wall above the opening.
Key facts
- Box sizes: 6.5, 7, 8, 9, 10 and 12 in nominal (165 to 300 mm); actual heights 6.575 to 12.008 in. Roll-A-Shield data
- The box is read from the curtain height, which is the clear opening height plus 2 in, not from the opening height alone. Roll-A-Shield data
- Boxes are about as deep as they are tall: about 6-5/8 in for a 6.5 in box up to about 12 in for a 12 in box.
- Surface mount: the wall above the opening must take the box's actual height plus about 2 in. Roll-A-Shield data
- When the axle would sag half an inch or more under the curtain, the box is stepped up one size. Roll-A-Shield data
Applies to: Roll-A-Shield rolling shutters on 38 mm and 55 mm insulated and 63 mm single-wall slats, surface (outside) or recessed (inside) mount; other makes use similar but not identical box charts.
The box (also called the housing, hood or cassette) holds the rolled-up curtain, so its size follows the length of curtain it has to hold and how thick that curtain is when rolled. Width is not what sets the size: the box runs the full width of the shutter, and width only matters on a wide, heavy shutter whose axle would sag (see below). Why taller curtains need bigger boxes is explained in Why taller shutters need bigger boxes.
Which box size does my shutter need?
Find your curtain height, then read across for your slat. The curtain height is the clear opening height plus 2 in, because the bottom slat stays in the rails below the box when the shutter is fully up. The chart picks the smallest box that holds the curtain.
| Box (nominal) | Actual height | 38 mm insulated | 55 mm insulated, 60 mm axle | 55 mm insulated, 70 mm axle | 63 mm single-wall, retention every slat | 63 mm single-wall, every other slat or none |
|---|---|---|---|---|---|---|
| 6.5 in (165 mm) | 6.575 in | up to 60 in | — | — | up to 48.5 in | up to 57.5 in |
| 7 in (180 mm) | 7.204 in | up to 70 in | — | — | up to 77 in | up to 82 in |
| 8 in (205 mm) | 8.150 in | up to 110 in | up to 82 in | up to 78 in | up to 97 in | up to 105 in |
| 9 in (230 mm) | 9.055 in | up to 134 in | up to 114 in | up to 99 in | up to 122 in | up to 132.5 in |
| 10 in (254 mm) | 10.039 in | over 134 in | up to 150 in | up to 124 in | up to 150 in | up to 162 in |
| 12 in (300 mm) | 12.008 in | — | over 150 in | over 124 in | over 150 in | over 162 in |
Read the 55 mm columns by axle. A motorized 55 mm shutter uses the 60 mm axle when the curtain weighs 140 lb or less and the shutter is 144 in wide or less, and the 70 mm axle above either limit; an OZRoll battery motor always uses a 60 mm axle. The 63 mm columns depend on how often the slats carry end-retention pieces in the rails.
Example: a 38 mm shutter over a 58 in tall opening has a 60 in curtain and still fits the 6.5 in box; a 59 in opening (61 in curtain) needs the 7 in box.
Two things can move the box up from the chart. On a wide, heavy shutter the axle bends slightly under the curtain, and when that sag would reach half an inch the box is stepped up one size so the curtain does not rub. You can also ask for a bigger box, but not a smaller one than the chart gives. Spring-loaded shutters are limited to a box of 10 in or smaller.
How far does the box stick out from the wall?
About as far as it is tall. The boxes are close to square in section, with the front bottom corner bevelled, and the end caps are as wide as they are tall.
| Box (nominal) | Sticks out from the wall, about |
|---|---|
| 6.5 in | 6-5/8 in |
| 7 in | 7-1/4 in |
| 8 in | 8-1/8 in |
| 9 in | 9 in |
| 10 in | 10 in |
| 12 in | 12 in |
Anything that pushes the shutter off the wall adds to this. Where a door handle, hinge or trim sticks out, the shutter is stood off the wall on furring, which adds its own thickness; see Do I need furring?. The guide rails stand out much less than the box.
How much headroom do I need above the opening?
On a surface mount, the box's actual height plus about 2 in of flat wall above the opening. The extra 2 in is where the bottom slat parks below the box, so the whole opening is clear when the shutter is up. Nothing extra is needed below the sill, because the guide rails stand on it.
On a recessed (inside) mount, the same box and 2 in come out of the top of the opening instead, so you lose that much of the view when the shutter is up. The two mounts are compared in Inside or outside mount.
Worked example, from Roll-A-Shield's standard 48 x 48 in unit: with mini rails and a 6.5 in box it is 52-1/8 x 56-5/8 in overall; with standard rails and an 8 in box, 54-3/4 x 58-1/8 in.
Can I hide the box?
Yes. In new construction the box can sit in a soffit or a framed pocket, which has to be a little larger than the box. Staff have quoted about 7 to 7-1/2 in of depth for a 6.5 in box on past jobs, but that figure came from specific jobs, not a fixed spec, so get the allowance for your opening from your quote or shop drawing before framing. Have the motor and control wiring run before the soffit is closed; mains wiring is work for a licensed electrician. A box sealed in is hard to reach for repairs, so an access panel to the box is available as a special order, and a reverse mount is one way to hide the box behind a flush face. Planning a pocket is covered in Planning a hidden shutter box.
What next
Your quote or shop drawing gives the exact box for each shutter. Send your clear opening sizes on a quote request, or call (480) 921-0200 if you are framing a pocket and need the box size first.
Watch it done
Roll-A-Shield Measure Guide
The written steps on this page are the reference; the video shows the same job.
Frequently asked questions
How big is the box for a ten-foot-tall shutter?
For a 120 in opening the curtain is about 122 in: a 9 in box on 38 mm insulated slat or 63 mm single-wall, and a 10 in box on 55 mm insulated (on either axle), before any step-up for axle sag.
Can I choose a smaller box than the chart gives?
No. You can ask for a larger box, but never one smaller than the chart minimum, because the rolled curtain would not fit.
Can the box be hidden in a soffit or a pocket?
Yes, in a pocket a little larger than the box. Staff have quoted about 7 to 7-1/2 in of depth for a 6.5 in box on past jobs, but that is a starting reference, not a fixed spec, so get the figure for your opening before framing. An access panel to reach the box for repairs is available as a special order.
Do the guide rails stick out as far as the box?
No, the rails stand out much less than the box. Each rail adds 2.0875 to 3.346 in to the width on its side of the opening, depending on the rail type; that is its width across the face, not how far it stands out.
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.