Sizing and engineering · Rolling Shutter Guide
Why do my slat options shrink as the rolling shutter gets bigger?
Each slat has its own maximum width, height and area, and the area usually runs out first. On Roll-A-Shield shutters the 38 mm insulated slat stops at 112 sq ft, the 55 mm insulated at 156.5 sq ft and the 63 mm single-wall at 200 sq ft, so a larger opening leaves fewer slats. Manual operators drop out sooner still.
Key facts
- 38 mm insulated: up to 159 in wide and 112 sq ft of clear opening. Roll-A-Shield data
- 55 mm insulated: up to 224 in wide and 156.5 sq ft, motorized only. Roll-A-Shield data
- 63 mm single-wall: up to 222 in wide and 200 sq ft, the largest area of any slat. Roll-A-Shield data
- Every slat goes to 216 in tall, but the area limit binds first: a 38 mm shutter 159 in wide caps at about 101 in tall. Roll-A-Shield data
- Strap, crank and wand shutters are capped at a curtain of about 50 lb, which works out to roughly 55 sq ft of 38 mm curtain. Roll-A-Shield data
Applies to: Roll-A-Shield 38 mm and 55 mm insulated and 63 mm single-wall (solid and perforated) rolling shutters with strap, crank, wand, spring or motor operation.
On a small window almost any slat and any operator will do. As the opening grows, the list shortens: first the manual operators drop out, then the lightest slat, then the next. This page shows where each cut-off falls on Roll-A-Shield shutters and why.
What are the size limits for each slat?
Each slat profile has a maximum width, height and area, all measured on the clear opening.
| Slat | Max width | Max height | Max area | Operators |
|---|---|---|---|---|
| 38 mm insulated | 159 in | 216 in | 112 sq ft | Strap, crank, spring or motor |
| 55 mm insulated | 224 in | 216 in | 156.5 sq ft | Motor only |
| 63 mm single-wall | 222 in | 216 in | 200 sq ft | Spring or motor in most cases |
| 63 mm perforated | 222 in | 216 in | 200 sq ft | As 63 mm single-wall |
These are the largest sizes Roll-A-Shield builds; shutters near the top of each range are reviewed by the factory before they are accepted. Full profile dimensions are on rolling shutter slat specifications.
Why does area run out before width or height?
Because the maximum width and the maximum height can't both be used on one shutter. Multiply the two and the result is well over every slat's area limit, so the area caps the height of a wide shutter and the width of a tall one.
| Slat | At full width, tallest it can be | At full height, widest it can be |
|---|---|---|
| 38 mm insulated | about 101 in at 159 in wide | about 75 in at 216 in tall |
| 55 mm insulated | about 100 in at 224 in wide | about 104 in at 216 in tall |
| 63 mm single-wall | about 130 in at 222 in wide | about 133 in at 216 in tall |
To check an opening, multiply the clear width by the clear height in inches and divide by 144 to get square feet, then compare it with the table.
Which slats are left as the opening gets bigger?
Working up from a small opening:
- Up to 112 sq ft and 159 in wide: all three slats are possible.
- Above that, up to 156.5 sq ft: the 38 mm slat drops out, leaving the 55 mm insulated and the 63 mm single-wall.
- Above 156.5 sq ft, up to 200 sq ft: only the 63 mm single-wall slat, solid or perforated.
- Above 200 sq ft: no single shutter; the opening is split into two or more. See covering a 16-20 ft opening.
One edge case runs the other way: between 222 and 224 in wide, only the 55 mm slat is long enough, provided the area stays within its limit.
How does the operator narrow the choice?
Manual operators run out well before the slats do. On Roll-A-Shield shutters:
| Operator | Limit |
|---|---|
| Pull strap | up to 24 sq ft and 120 in wide |
| Crank strap | up to 64 sq ft |
| Strap, crank or wand | a curtain of about 50 lb at most |
| Spring-loaded | up to 192 in wide, 120 in tall, 144 sq ft, in a box of 10 in or smaller |
| Motor | up to the slat's own limits, with a motor sized to the curtain weight |
The weight cap is the one that usually bites. At the 38 mm slat's sizing weight of 0.92 lb per sq ft, the cap works out to roughly 55 sq ft of curtain, and the curtain is the clear opening plus about 2 in of height.
The slat and the operator also limit each other. The 55 mm slat is motorized only, so a buyer who wants a strap or crank is choosing the 38 mm slat; a buyer who wants a spring-loaded shutter is choosing the 38 mm or the 63 mm single-wall. How big a manual shutter can be and spring-loaded shutters go into those limits in detail.
Why do bigger shutters need a different slat at all?
Weight, span and the size of the roll. A larger curtain weighs more, so it needs a stronger axle and motor; a wider one bends its axle more, which is covered in why wide shutters sag; and a taller one makes a bigger roll that needs a bigger box. Each slat family also has its own range of boxes: the 38 mm slat runs from a 6.5 in box to 10 in at most, the 55 mm slat starts at 8 in and goes to 12 in, and the 63 mm single-wall slat uses 6.5 to 12 in.
Near the top of its range the lightest slat is also the least forgiving. Roll-A-Shield's field guidance is that a 38 mm curtain around 144 in wide and 96 in tall is not recommended where the shutter will stay closed for long periods; the 55 mm slat is preferred there.
Do other choices change with the slat?
Yes, a few. The 55 mm insulated slat comes vented only, the 63 mm single-wall slat cannot be vented, and the 63 mm single-wall slat always runs in an end-retention rail. If a feature you want only comes on one slat, that slat's size limits are the ones that apply.
For a specific opening, request a quote or call (480) 921-0200 with the clear width and height; the factory checks the slat, operator, box and axle together.
Frequently asked questions
Which slat covers the biggest opening?
The 63 mm single-wall slat, at up to 200 sq ft of clear opening and 222 in wide. The 55 mm insulated slat goes slightly wider, to 224 in, but only up to 156.5 sq ft.
Can the factory build past these limits?
No. These are the largest sizes Roll-A-Shield will build, and sizes near them are reviewed by the factory before they are accepted. A larger opening is covered with two or more shutters.
Why can't I have a pull strap on my big window?
A pull strap is limited to 24 sq ft and 120 in wide, a crank strap to 64 sq ft, and every strap, crank or wand shutter to a curtain of about 50 lb. Past that, the choices are a spring-loaded shutter or a motor.
Is the limit measured on the opening or the whole shutter?
On the clear opening. Roll-A-Shield checks the width, height and area of the opening itself, before the guide rails and box are added.
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.