Key facts

• Roll-A-Shield shutter boxes come in six sizes, from 6.5 in (165 mm) to 12 in (300 mm); the box size is chosen by the height of the curtain it has to hold. Roll-A-Shield data
• Each guide rail takes up 2.0875 in (mini), 2.625 in (mini wide), 2.944 in (end retention) or 3.375 in (standard) per side of the opening. Roll-A-Shield data
• A 63 mm single-wall extruded curtain always runs in an end-retention rail, which holds the slat ends inside the rail. Roll-A-Shield data
• Strap, crank-strap and crank-wand operators are limited to a curtain of about 50 lb; heavier curtains need a spring or a motor. Roll-A-Shield data
• A shipped manual shutter arrives as the assembled box (slat roll on the axle), two guide rails, a U-channel if ordered, the strap box or crank box, and a parts kit with diamond roller, anti-lift brackets and rail plugs. Roll-A-Shield data

Applies to: Roll-down (rolling) shutters of any make with a box above the opening; Roll-A-Shield 38 mm and 55 mm insulated and 63 mm single-wall extruded shutters with strap, crank, spring or tubular-motor operation.

Owners, installers and catalogs often use different words for the same piece. This page names each part of a typical rolling shutter, gives its other names, and links to the guides that work on it. The names are the common trade terms; the sizes are Roll-A-Shield's.

What are the main parts of a rolling shutter?

Every rolling shutter has a box at the top, a slat curtain that rolls into it, two guide rails, and something that turns the axle.

The housing: what is inside the shutter box?

The box holds the axle, the operator and the curtain when it is rolled up.

• Box (housing, hood). An aluminum enclosure, usually made as a front-bottom half and a top-back half, with a removable front cover held by screws. It can sit on the wall face or be recessed. See inside mount vs outside mount.
• End caps (ears). Shaped like the box profile, one left and one right. The ears slide down into the tops of the guide rails. They are cast aluminum and can crack if forced or used as a lifting point.
• Safety plates. Metal plates inside each end of the box that stop the turning slat roll from catching on the end caps.
• Axle (tube). A tube, aluminum (an extruded octagon) or steel, that the curtain winds onto. Roll-A-Shield uses 40, 60 and 70 mm axles: 40 mm on most strap and crank shutters, and 60 or 70 mm on motorized, spring and single-wall shutters, depending on the slat, the curtain's weight and width, and the box size.
• Hanging straps (T-straps). T-shaped straps riveted or screwed to the axle that slide onto the top slat and carry the curtain.
• Axle insert and bearing (idler end). The plug and bearing at the non-motor end that let the axle turn in the end cap.

The box size is set by how tall the curtain is, because a taller curtain makes a fatter roll.

The curtain: what are slats and the bottom bar?

The curtain is the row of interlocking aluminum slats that does the work: privacy, insulation and security.

• Slats. Roll-formed aluminum filled with insulating foam, or thicker extruded aluminum with no foam. Vented slats have small light slits that let light through when the shutter is partly open and close up when it is fully down.
• Slat end plugs. Small plastic plugs fitted to the ends of the slats.
• Bottom bar (end slat). A single extruded slat at the bottom of the curtain with a weather seal along its underside. On some shutters it carries a weight bar inside, and on manual shutters it can carry the lock.
• Stops. On strap and crank shutters, stop plugs on the bottom bar keep the curtain from being pulled up into the box. Motorized shutters do not need them because the motor's limits stop the curtain.

Which slat suits which job is covered on the insulated slats and extruded shutters pages.

The guides: what do guide rails and U-channels do?

Guide rails hold the curtain edges, and the slat you choose decides the rail.

• Guide rails (tracks). Aluminum channels screwed to the wall on each side, with a felt or rubber weather strip in the slat channel. The screw holes are hidden with color-matched rail plugs (hole covers).
• Entry rollers, guides and flares. The top of each rail guides the curtain in. Boxes of 10 in and larger can take an entry roller; a roller does not fit in a box of 9 in or smaller, so those use a flared rail top or a plastic entry guide.
• End-retention rail. A rail with an extra channel that catches retention heads on the slat ends, so wind or a pry bar cannot push the curtain out of the track. It has a snap-in cover over the screws.
• U-channel. An extruded channel across the bottom that the curtain closes into. It is needed only where there is no flat surface to land on, or for extra light sealing, and is screwed to the bottom of both rails.

The drive: what makes a rolling shutter go up and down?

The operator turns the axle. Strap and crank operators are for lighter curtains, up to about 50 lb; anything heavier takes a spring or a motor.

• Pull strap. A flat strap wound on a strap disc on the axle, passed through the wall, over a diamond roller (the wall guide where the strap comes in) and into a pull-strap box, a spring drum that takes up the slack. Limited to 24 sq ft and 120 in wide. See replacing a strap.
• Crank box (crank strap). The same strap, wound by a geared box turned with a removable handle; for curtains up to 64 sq ft. Do not open it.
• Crank wand (gear). A gear at the end of the axle, turned with a removable wand or crank handle.
• Spring. A spring, set by a black barrel-shaped tensioner at one side of the shutter and locked with a pin, balances the curtain so it is pushed up and pulled down by hand. Spring shutters ship with no tension; it is set on site with two tensioning rods.
• Tubular motor. A motor inside the axle, fitted with a crown at the motor head and a drive that turns the tube. It runs on 120 V AC, or on its own battery for solar and battery motors. Brands include Gaposa, Somfy, SIMU and OZRoll. See rolling shutter motors and replacing a motor.
• Manual override (CMO). A motor with a gear that a wand can turn through the end cap when the power is out. See manual override.
• Controls. Wall switch, outdoor key switch, handheld or in-wall remote, key fob, keypad, or a smartphone app (for example through a Bond Bridge). Setup is on the Gaposa programming and Somfy limits pages.

Accessories: locks, anti-lift brackets, storm bars and furring

Not every shutter has these.

• Locks. Manual shutters can take a key lock, slide lock or thumb-turn lock on the bottom bar, fitted on the box side or the back side. Motorized shutters do not use these; the motor holds the curtain down.
• Anti-lift brackets. C-shaped brackets inside the box that stop a manual shutter being forced up from outside.
• Storm bar. A removable vertical bar that stands behind the middle of the curtain, for patio and carport shutters with nothing solid behind them. A single-wall shutter with end retention never needs one.
• Furring (build-out). Rectangular aluminum tube, powder-coated to match the shutter, that moves the shutter out past a door handle, hinge or trim.
• Pull-down hook. A pole and hook, supplied with larger shutters, for pulling the bottom bar down when it is out of reach.

What comes in the box when a shutter ships?

A manual shutter ships as the assembled box with the slat roll already on the axle, two guide rails, a U-channel if ordered, the pull-strap box or crank box and handle, and a parts kit with a diamond roller, anti-lift brackets and rail plugs. Spring shutters add two tensioning rods. The parts kit includes a bag of standard fasteners; the manual also recommends screw types for brick and concrete, metal, wood and stucco. The strap and crank install guide walks through fitting each part, and how to measure explains where the rail and box dimensions come from.

What next

Straps, diamond rollers, crank handles, remotes and hanging straps are in the Roll-A-Shield parts store. For a box, end cap, slat or rail, call (480) 921-0200 with a photo and the box size. In metro Phoenix, Roll-A-Shield's service team services rolling shutters of any make.

Watch it done

The Anatomy of a Roll-A-Shield Shutter

The written steps on this page are the reference; the video shows the same job.

Frequently asked questions

What is the box on top of a rolling shutter called?

Box, housing, hood, headbox and cassette all mean the same part: the aluminum enclosure above the opening that holds the axle, the operator and the rolled-up curtain. It has a removable cover held by screws.

What are the T-straps on a rolling shutter?

T-straps, also called hanging straps or hangers, are the T-shaped pieces riveted or screwed to the axle that slide onto the top slat. They are what connects the curtain to the axle.

Do I need a U-channel?

Only if the bottom of the opening has no flat surface for the shutter to rest on, or you want a better light seal. Where it is used, the U-channel is screwed to the bottom of both guide rails.

How wide are rolling shutter guide rails?

On Roll-A-Shield shutters a rail takes 2.0875 in per side (mini), 2.638 in (mini wide), 2.944 in (end retention) or 3.346 in (standard). The rail is set by the slat you choose.

Can I buy a single part, or only a whole shutter?

Single parts are sold: straps, diamond rollers, crank handles, remotes and hanging straps are in the online parts store, and shutter boxes, slats and other parts are ordered by phone at (480) 921-0200. Slats, axles and rails are cut to your measurements when ordered.

Related questions

• How do I measure for a rolling shutter?
• Inside mount or outside mount: which is right for a rolling shutter?
• What is a manual override, and do I need one?
• How do I replace a broken rolling shutter strap?
• How do I replace a rolling shutter motor?
• How do I install a strap or crank rolling shutter?
• Rolling shutter accessories
• Somfy vs Gaposa: rolling shutter motors