Sizing and engineering · Rolling Shutter Guide
Can one rolling shutter span a very wide opening, or do I split it with a post?
One motorized shutter can span up to 224 in (18 ft 8 in) of clear opening on the 55 mm insulated slat, or 222 in on 63 mm single-wall, if the height stays inside the slat's area limit. Beyond that, two shutters, each with its own rails, box and motor, meet on a solid post or mullion.
Key facts
- The widest single Roll-A-Shield shutter is 224 in clear on the 55 mm insulated slat and 222 in on the 63 mm single-wall slat; the 38 mm slat stops at 159 in. Roll-A-Shield data
- At 16 ft (192 in) wide, the area limit allows about 117 in of height on 55 mm insulated and 150 in on 63 mm single-wall. Roll-A-Shield data
- Two shutters never share a guide rail, a box or a motor; each is built as its own unit. Roll-A-Shield data
- Side-by-side motorized shutters can be wired to share one power point, and one remote can run both. Roll-A-Shield data
- A rolled curtain heavier than 80 lb ships separately from its box. Roll-A-Shield data
Applies to: Wide openings such as patios, lanais, carports, storefronts, garages and long window walls; Roll-A-Shield 55 mm insulated and 63 mm single-wall shutters. The 38 mm slat does not reach this width.
A 16 ft opening can usually take one shutter; a 20 ft opening cannot. The deciding numbers are the slat's maximum width and its maximum area, both measured on the clear opening. In between, the answer depends on how tall the opening is and which slat you want.
How tall can one shutter be at each width?
Work it out from the area limit: the wider the shutter, the shorter it has to be.
| Clear opening width | One 55 mm insulated shutter, tallest | One 63 mm single-wall shutter, tallest |
|---|---|---|
| 16 ft (192 in) | about 117 in | about 150 in |
| 17 ft (204 in) | about 110 in | about 141 in |
| 18 ft (216 in) | about 104 in | about 133 in |
| 18 ft 6 in (222 in) | about 101 in | about 129 in |
| 18 ft 8 in (224 in) | about 100 in | too wide; split |
| 19 ft and wider | too wide; split | too wide; split |
The heights come from 156.5 sq ft for the 55 mm slat and 200 sq ft for the 63 mm slat, divided by the width. The 38 mm insulated slat is not in the table because it stops at 159 in. Shutters this size are reviewed by the factory before they are built.
The whole shutter is wider than the opening by one guide rail on each side: on standard rails that is 3.346 in per side, so a 224 in opening becomes about 230-3/4 in overall.
What does one big shutter involve?
A heavy curtain, a big axle and a bigger box. A 16 ft by 9 ft (192 by 108 in) 55 mm curtain weighs about 160 lb at the sizing weight of 1.11 lb per sq ft. At that weight and width a 55 mm shutter moves up from the 60 mm axle to the 70 mm axle, which is chosen once the curtain passes 140 lb or the shutter is wider than 144 in. Over a long span the axle also bends slightly under the curtain; when the calculated sag reaches half an inch, the factory steps the box up one size so the curtain does not rub.
Handling grows with it. A rolled curtain over 80 lb ships separately from its box and is loaded onto the axle on site. On Roll-A-Shield's own jobs, shutters over 9 ft wide are scheduled with two technicians, and units approaching roughly 200-250 lb are scheduled with a crew of three or four. Do not plan to lift a curtain this size with too few people; see Lifting a heavy curtain.
How does splitting with a post or mullion work?
Two shutters sit side by side, each in its own pair of guide rails, with its own box and its own motor. Where they meet, their two inner rails sit next to each other on a post or mullion, so that support has to be solid and flat enough to screw both rails into.
- Where to split. At an existing mullion or post where possible; the split does not have to be in the middle, and it is agreed with your sales rep for function and looks.
- How to measure. On a surface mount, each shutter is measured from its outer edge to the center line of the shared mullion.
- What you lose. The rails at the split block some opening: two rail widths, from 2.0875 in each on mini rails to 3.346 in each on standard rails.
- Power and control. The two shutters can be wired so power is brought to one point, with one motor's lead run into the next box, and one multi-channel remote or switch can run both. The mains wiring itself is work for a licensed electrician, following the motor maker's junction-box rule.
Tip: Plan the post before the wall is finished. Its exact minimum size depends on the rail type, so ask for it with your quote rather than guessing.
When is splitting the better choice even if one shutter fits?
When there is already a post, a mullion or a column in the opening, the shutters can follow it, which keeps each one lighter. Whichever way you go, a long shutter needs support along the bottom: where the pad or sill under it falls short, an L-angle or a U-channel gives the bottom bar something to close on, and it should be noted on the measure form. Patio and carport layouts are covered in Enclosing a patio, lanai or carport.
What next
Send the clear-opening width and height, where any posts or mullions are, and where power is on a quote request, or call (480) 921-0200. The motor that suits each half is explained in What size motor does my rolling shutter need?.
Watch it done
Commercial measuring tips: splitting a wide opening at a mullion
The written steps on this page are the reference; the video shows the same job.
Frequently asked questions
Can two shutters share one box or one motor to look like a single unit?
No. Each shutter is built as a single unit with its own box and motor. Two motorized shutters can be wired to one power point, and one remote can control both.
Does the split have to be in the middle?
No. Where the split falls is agreed between you and the sales rep, usually at an existing post or mullion and for looks; the two shutters do not have to be the same width.
How wide does the post between two shutters need to be?
Wide enough to carry two guide rails side by side and solid enough to screw both into. Rail widths depend on the slat and rail type, so ask for the post size for your shutter before framing it.
Can I make it two manual shutters instead of one motorized one?
Only if each half stays inside the manual limits: a curtain of about 50 lb for strap and crank shutters, or the spring-loaded limits of 192 in wide, 120 in of curtain height and 144 sq ft. The 55 mm insulated slat is motorized only.
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.