Parts, boxes, rails and mounting · Rolling Shutter Guide
Inside mount or outside mount: which is right for a rolling shutter?
An outside (surface) mount fixes the box and guide rails to the wall around the opening, so the whole opening stays clear; it suits most windows and doors. An inside (recessed) mount fits the entire shutter within the opening. It looks flush, but needs a solid, square reveal deep enough for the box and gives up some opening.
Key facts
- For an outside (surface) mount you give the inside size of the opening and the rails are added outside it; for an inside (recessed) mount you give the overall size of the space the whole shutter must fit. Roll-A-Shield data
- Guide rails take 3.375 in per side on standard rails, 2.0875 in on mini rails, 2.625 in on mini-wide rails and 2.944 in on end-retention rails. Roll-A-Shield data
- Roll-A-Shield boxes come in 6.5, 7, 8, 9, 10 and 12 in (165 to 300 mm), chosen by curtain height and slat type. Roll-A-Shield data
- Overall shutter height is the clear opening height plus the box height plus about 2 in for the bottom slat, which stays in the rails when the shutter is open. Roll-A-Shield data
- On a recessed mount the rails are screwed sideways into the walls of the opening and carry the whole weight of the shutter, and the shutter is built with different axle end parts, so the mount must be chosen on the order. Roll-A-Shield data
- Roll-A-Shield furring is 1 x 2 in aluminum tube: laid flat it stands the shutter 1 in off the wall, on edge 2 in. Roll-A-Shield data
Applies to: Rolling shutters (roll-down security and storm shutters) of any make with a head box and side guide rails; Roll-A-Shield 38 mm and 55 mm insulated and 63 mm single-wall shutters with any operator.
People use several names for the same two choices. An outside mount is also called a surface or "overall" mount. An inside mount is also called a recessed mount, and when the opening is boxed in on the sides or top it is called a trapped opening. Both put the shutter on the outside of the glass; neither means a shutter inside the room.
Inside mount vs outside mount at a glance
| Outside (surface) mount | Inside (recessed) mount | |
|---|---|---|
| Where it fastens | Box and rails screwed to the wall face around the opening | Box and rails inside the opening; rails screwed sideways into the reveal |
| What you measure | Inside width and height of the opening (A and B on the measure sheet) | Overall width and height of the space the shutter must fit (C and D) |
| Overall width | Opening width plus 2 rail widths | The width of the space, less a little fitting room |
| Wall needed above the opening | Box height plus about 2 in | None; the box sits in the top of the opening |
| Opening left clear when the shutter is up | All of it | Less 2 rail widths and the box plus about 2 in |
| Look | Box and rails stand proud of the wall | Flush with the wall face |
| What the wall must offer | A flat face around the opening; furring where anything sticks out | Solid, square sides deep enough for the box |
What is the difference between an inside and an outside mount?
The difference is what the shutter is fastened to. On a surface mount, the most common type, the rails are fixed face-on to the wall either side of the opening and the box to the wall above it. On a recessed mount the box and rails sit inside the opening, and the rails are drilled through their sides into the walls of the opening; those rails then carry all of the shutter's weight.
On Roll-A-Shield shutters the choice also changes the build: a recessed unit is made with self-bearing axle end parts in place of the standard bearing, so the mount has to be specified on the order rather than decided at install. Roll-A-Shield's order system also takes two mixed configurations, recessed-surface and surface-recessed, for openings that do not fit either pure case.
How do I measure for each mount?
Measure the width and height at several points, because few openings are square, and record the smallest and largest of each. Then give one of two sizes, never both:
- Outside (surface) mount: the inside width and height of the opening. The guide rails are added outside it.
- Inside (recessed) mount: the overall width and height of the space, so the whole shutter, box and rails included, fits within it.
On a surface mount, installers usually leave about 1/4 to 1/2 in of wall showing between the window frame and the inner edge of each rail (the reveal), so the rail lands fully on the wall rather than half on the frame, with some forgiveness on uneven brick or stucco. On a trapped opening, send the tightest reading and say the opening is trapped; the shutter needs a little fitting room so it slides in without scraping, so agree with Roll-A-Shield who allows for it before you order, and it is neither missed nor taken twice. Every Roll-A-Shield dimension is then rounded up to the next 1/8 in. The full method is in How to measure for a rolling shutter.
How much room does the box need above the window?
On a surface mount, plan for the box's height plus about 2 in of wall above the opening; the extra 2 in is the bottom slat, which stays in the rails below the box when the shutter is fully up. On a recessed mount the same box and 2 in come out of the top of the opening instead. The box is chosen automatically from the curtain height and slat type, where the curtain height is the clear opening height plus about 2 in; use this as a sizing guide, not a promise for your order.
| Box (nominal) | Actual height | 38 mm insulated, curtain up to | 55 mm insulated, curtain up to | 63 mm single-wall, curtain up to |
|---|---|---|---|---|
| 6.5 in (165 mm) | 6.575 in | 60 in | not used | 48.5-57.5 in |
| 7 in (180 mm) | 7.204 in | 70 in | not used | 77-82 in |
| 8 in (205 mm) | 8.150 in | 110 in | 78-82 in | 97-105 in |
| 9 in (230 mm) | 9.055 in | 134 in | 99-114 in | 122-132.5 in |
| 10 in (254 mm) | 10.039 in | taller curtains | 124-150 in | 150-162 in |
| 12 in (300 mm) | 12.008 in | not used | taller curtains | 215-252 in |
In the 55 mm column the lower figure is for the 70 mm axle that a motorized 55 mm shutter normally uses and the higher one for a 60 mm axle; in the 63 mm column it depends on whether every slat or every other slat is retained. "Taller curtains" means curtains above the last figure in that column. Very wide units can step up one box size to limit axle sag. A recessed mount also needs the opening to be deep enough, front to back, to take the whole box; ask for the exact box dimensions for your size before you commit to it.
How wide are the guide rails, and how much opening do I lose?
Each guide rail takes a fixed width per side, set by the rail the slat needs.
| Rail | Width per side | Used with |
|---|---|---|
| Mini | 2.0875 in (about 53 mm) | 38 mm insulated slats |
| Mini-wide | 2.638 in (about 67 mm) | 38 mm insulated slats, the default above 120 in wide |
| Standard | 3.346 in (about 86 mm) | 55 mm insulated slats |
| End-retention | 2.944 in (about 75 mm) | 63 mm single-wall slats, which always run in it |
On a surface mount those widths are added outside the opening. A 38 mm shutter for a 48 × 48 in opening runs on mini rails with a 6.5 in box, so it comes out about 52 in wide and about 56-1/2 in tall: it needs just over 2 in of wall on each side and about 8-1/2 in above the opening.
On a recessed mount the same allowances come out of the opening. Fit the same 38 mm shutter into a 48 × 48 in recess and, with the shutter up, a little under 44 in of clear width and about 39-1/2 in of clear height remain.
When do you need a build-out (furring) or a mixed mount?
You need furring when anything stands proud of the wall in the shutter's path, such as a door handle, a casement window hinge or trim; without it the closing curtain hits the obstruction and will not close. Furring lifts the rails and box off the wall:
- Roll-A-Shield supplies 1 × 2 in rectangular aluminum tube, powder-coated to match and cut to the shutter's size; laid flat it stands the shutter 1 in off the wall, on edge 2 in.
- Order it for all sides, or only the top, bottom or sides that need it.
- It is installed level and plumb, aligned to the shutter's outer dimensions, before the rails go on.
Build-outs are also how Roll-A-Shield handles uneven faces such as tile, brick, stone and stucco, protruding bolts, and walls without enough depth. If you are unsure of the width, specify a slightly narrower shutter and add a build-out rather than ordering it too wide.
If the opening has no flat sill for the closed slats to rest on, add a U-channel at the bottom; it also improves the light seal.
Which mount suits my opening?
| Your opening | Usual choice |
|---|---|
| Window or door in a flat wall, little or no reveal | Outside (surface) mount |
| Door with a handle, or a window with hinges or trim that stick out | Surface mount on furring |
| Deep, square reveal in solid block or brick, and a flush look wanted | Inside (recessed) mount, if the loss of opening is acceptable |
| Niche or tiled face you would rather not drill | Recessed mount, specified on the order |
| Little wall above the opening (soffit, ceiling or roofline close above) | Recessed mount, if the opening is deep enough for the box |
| Patio or carport enclosure with no solid backstop | Either mount, plus a storm bar |
Before you settle on a mount, check the headroom for the box, the wall or stucco clearance for the rails, and anything in the way, such as retractable screens, swing-out doors or cabinets.
Can I install either mount myself?
Roll-A-Shield's self-install guides and videos walk through a surface mount; the steps are in Install a strap or crank shutter, and Can I install rolling shutters myself? covers tools, people and time. A recessed install is less forgiving because the rails carry the full load through the reveal, so call before you start one.
Safety: The box must be fastened to a strong, stable structure. Screw it at each corner, and add a third screw in the middle on shutters over 8 ft wide. Lift the box with a helper and handle it with care; the cast-aluminum end caps (the ears) can break under too much force or weight.
Stop: A wired motor needs a power source within 3 ft of the shutter, and mains wiring is a job for a licensed electrician, who follows the motor maker's rule: terminate the motor cable in a listed junction box, and do not run the motor cable through the wall.
What next
Measure using How to measure for a rolling shutter, note the mount on the measure sheet, and send photos of the opening with your sizes. To check which mount fits, call Roll-A-Shield at (480) 921-0200 or request a quote.
Watch it done
Surface mount vs recessed mount rolling shutters
The written steps on this page are the reference; the video shows the same job.
Frequently asked questions
Does an inside-mounted shutter block more light?
Yes. When it is open, a recessed shutter still occupies both rail widths at the sides and the box plus about 2 in at the top of the opening. A surface-mounted shutter sits outside the opening and leaves all of it clear.
What is a trapped opening?
One boxed in on the sides or top, by columns, block, a ceiling or a soffit, so the shutter must fit inside it. Measure at several points, send the tightest reading and say the opening is trapped. The shutter needs a little fitting room so it goes in without scraping; agree with Roll-A-Shield who allows for it before you order, so it is neither missed nor taken twice.
What does 'thru the throat' mean?
It is dealer shorthand for a recessed (inside) mount. If you hear it, confirm that is what is meant before the shutter is ordered.
Is an inside mount the same as mounting the shutter inside my house?
No. Inside mount means inside the window or door opening, still on the outside of the glass. A shutter mounted inside the room is a reverse-mount build with different dimensions; decide which you want before the order goes into production.
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.