How to measure a window for an Ozroll roller shutter
The tool above does the arithmetic. This is the same method written out, so you can read it through before you pick up the tape, or check it afterwards.
What you need
A steel tape measure and something to write on. A cloth or fibreglass tape stretches, and over a two-metre window that stretch is enough to matter. Measure to the nearest millimetre and write every measurement down as you take it — not afterwards.
Step 1 — decide how the shutter will be fitted
This decision comes first, because the two fitting methods work in opposite directions.
Face fit, also called wall mounted, sits on the face of the wall and covers the opening. The shutter is wider than the window, because the guide rails run down the wall either side of it. It is the easier of the two to install and it forgives a window that is out of square.
Reveal fit, also called in reveal or recess fit, sits inside the opening. The shutter is narrower than the window. It looks neater, but it needs a double-brick cavity wall to fix into, there is no margin for error in the measurements, and the guide rails will stop any window that opens outward from opening.
Step 2 — measure the height
Measure both sides of the window, from the sill up to the top of the opening. If the window runs up to the eave, measure from the underside of the eave instead.
Always use the larger of the two. Houses settle and windows are rarely square. Build to the shorter side and the shutter leaves a gap at the bottom of the taller side; build to the taller side and the installer simply trims the guide rail on site.
For a reveal fit, take 3mm off that larger figure so the shutter drops into the opening. If the other side is more than 3mm shorter again, expect to trim the guide on that side during installation.
Step 3 — measure the width
For a face fit, measure across the top and across the bottom, and use the larger. The shutter goes over the opening, so the smaller figure would leave it uncovered.
For a reveal fit, measure across the top, the middle and the bottom, use the smallest, and take 4mm off it. The shutter goes into the opening, so anything larger simply will not go in. The deduction applies every time, wherever the narrowest point happens to be — but measure the top carefully regardless, because the pelmet sits there and has no room to be wrong.
Those three reveal measurements also have to agree with each other. If the widest and the narrowest differ by more than a few millimetres, the guide rails cannot stay parallel and the curtain binds as it raises and lowers. At that point the opening will not take a reveal fit as it stands — either pack the guides out with aluminium angle or tube, or use face fit, which sits on the wall and does not care about the shape of the opening.
Step 4 — the head box
The head box is the housing the curtain rolls up into, and it comes in a fixed set of sizes. Each size has a maximum overall height that includes the box itself, which is why the box size and the total height decide each other: you work up from the smallest box until you find the first one whose limit your window fits inside.
Where the box sits is what makes the two fitting methods order different heights. On a face fit the box sits on the wall above the opening, so the height you order is the opening plus the box. On a reveal fit the box sits inside the opening, so the height you order is the opening less the small deduction — the box is already inside that figure.
Maximum overall height for each head box, including the box, on square boxing (SQ45):
| Head box | OZ-400, OZ-400 HDF and HDF Windlock | OZ-401 Extruded and Extruded Windlock |
|---|---|---|
| 150mm | 1300mm | 1100mm |
| 165mm | 1700mm | 1600mm |
| 180mm | 2135mm | 2000mm |
| 205mm | 3000mm | 2800mm |
| 230mm | 3800mm | 3400mm |
Step 5 — face fit only: the guides run past the sill
On a face fit the size you order is the whole shutter, so anything you need has to be in the figure you give. The guide rails have to finish below the opening, because the sill seal fixes to the bottom of them. How far below depends on what is under the window:
- Rendered or cement: 50mm below the opening.
- Face brick: down to the bottom of the first brick.
- Recessed sill brick: 25mm below the top of the first flush brick.
- Door opening: to the floor — which is already the bottom of the opening, so there is nothing to add.
One more thing that surprises people: when the curtain is fully rolled up, the bottom bar still hangs about 45mm below the head box. That much of the top of the window stays covered even with the shutter open.
And if the window sits tight under the eave there is no room above it for a head box at all, which usually rules out a face fit on that window.
Step 6 — check the whole shutter
Each profile has a maximum curtain width and a maximum curtain area. The area limit catches windows that pass every other check: a three-metre by three-metre window is inside the width limit and inside the height limit, and still too big overall on a domestic profile. Wide openings are usually solved with two shutters side by side.
The mistakes that cost money
- Measuring once. Both sides for height, two or three points for width, every time. A window that looks square usually is not.
- Using the wrong extreme. Largest for face fit, smallest for reveal. Get this backwards and the shutter either will not cover the opening or will not go into it.
- Forgetting the head box on a face fit. The ordered height is taller than the window by the height of the box — and taller again by the guide drop below the sill.
- Leaving the guide drop out. On a face fit nothing is added for you. If the guides need to finish 50mm below the opening, those 50mm have to be in the height you give.
- Ignoring what is around the window. Downpipes, meter boxes, taps, air conditioning units and security screens all get in the way of a shutter that measures up perfectly on paper.
Common questions
Is this an official Ozroll guide?
No. This guide is an independent reference published by Shutter Masters for Ozroll roller shutters. The figures and rules are built up from what experienced installers have learned on the job, and Ozroll has not published or endorsed this page.
What does this guide not cover?
This guide does not cover manual winder shutters, bay windows or corner windows, because those use different rules. This guide also stops at the size to order and does not cover installation.
What is the difference between face fit and reveal fit?
Face fit mounts the shutter on the wall over the opening, so it is wider than the window and the guide rails are added to your measurement. Reveal fit mounts it inside the opening, so it is narrower than the window and a small allowance is deducted. Face fit is easier to install and tolerates an out-of-square window; reveal fit looks neater but has no margin for error.
Do I measure the window or the opening?
The opening — the hole in the wall, not the glass and not the frame. If the frame or architrave protrudes past the wall, a face fit is measured from the outer edge of the architrave instead, and packers are used at installation.
My window is out of square. Which measurement do I use?
For a face fit, the largest. For a reveal fit, the smallest, less 4mm. If the three reveal widths differ from each other by more than a few millimetres, the opening will not take a reveal fit as it stands — the rails will not stay parallel and the curtain will jam. Packing the guides out with aluminium angle or tube, or moving to a face fit, are the ways around it.
What size head box do I need?
It depends on the height of the window and on the curtain profile. Each box size carries a maximum overall height including the box, so you take the smallest box whose limit your window still fits inside. A taller window needs a bigger box, and a bigger box makes the overall height taller again.
Can a roller shutter be fitted to a window that opens outward?
Yes, but face fit only. Casement, awning and hopper windows swing out into the opening, and a reveal-fitted guide rail sits exactly where the sash needs to travel.
How wide can a single roller shutter be?
It depends on the profile — a domestic profile spans less than an extruded one — and it is capped by area as well as by width. Anything beyond the limit is made as two shutters side by side rather than one.
How far below the window do the guide rails go?
On a face fit they finish below the opening so the sill seal can be fitted: about 50mm on a rendered or cement wall, down to the bottom of the first brick on face brick, or 25mm below the top of the first flush brick where the sill brick is recessed. A door opening needs nothing, because the guides run to the floor and the floor is already the bottom of the opening. That length is part of the height you order — it is not added for you.
Do I need an electrician?
For a hardwired electric motor, yes. A battery motor does not need one. Both can be operated by remote — a remote is a control method, not a type of motor.