How Do You Measure an Opening for a Zip Screen?

The Short Answer

Decide the mounting position first, because it determines what you measure. Then measure the width at the top, middle and bottom and the height at the left, centre and right, in millimetres, and record every reading along with both diagonals. Send those readings to the manufacturer with photos and a note of the fixing surfaces, and let them convert the readings into production sizes for their system.

Do not subtract anything yourself. Deductions and overlaps differ from system to system, and an adjustment made on site and again in the factory produces a screen of the wrong size.

What to Decide Before You Measure

A tape measure answers only part of the question. Two decisions come first.

Choose the mounting position

The same pergola bay can be measured in two different ways, depending on where the screen will sit. The table shows how the common situations differ.

Our zip screen systems page explains how the cassette, side channels and bottom bar fit together, which makes these choices easier to picture.

Check that a zip screen suits the opening

A zip screen depends on its side channels, so it needs straight, solid surfaces on both sides. If one side of the opening has no such surface, or the opening is unusually wide or high, raise this before measuring in detail. If you are still deciding on the system, our zip screen vs outdoor roller blind comparison sets out the differences.

How to Take the Measurements

Use a rigid steel tape, work in millimetres, and measure the actual structure rather than a drawing.

Measure width at three points

Measure at the top, middle and bottom of the opening, and write down all three. On an inside fit, the smallest reading usually matters most because it can limit what fits. Posts and beams can bow on long spans.

Measure height at three points

Measure at the left, centre and right, from the top fixing line down to the finished floor. Measure to the surface the bottom bar will actually meet. If tiles, decking or a threshold are still to be laid, say so and give the final level, because a measurement taken on an unfinished floor will be wrong.

Measure both diagonals

Measure from top left to bottom right and from top right to bottom left. If the two figures match closely, the opening is close to square. If they differ, one or more corners are out, and the width and height readings will show you where.

Here is how one opening might be recorded. The figures are only an example of the format, not target values or tolerances.

In this example, the height rises to the right and the diagonals differ, so the floor or the beam is probably sloping. That is what the manufacturer needs to see, and a single width and height would have hidden it.

How to Handle Openings That Are Not Square

Few outdoor openings are perfectly square or level. The problem usually has a solution, but only if it is known before production.

Sloping or stepped floors

A terrace is often laid with a fall for drainage, so the bottom bar may not meet the floor evenly along its width. Measure the height at more points if the floor changes level, and note any steps, drainage channels or tiles at different heights. A gap under the bottom bar affects how well the screen closes, so it is better to discuss it now than to find it at handover.

Leaning posts and uneven walls

Side channels run in a straight line, and they should not be forced to follow a post or a wall that is not straight. Hold a long straight edge or a level against each fixing surface and note how far it is out, and in which direction. Installers may be able to absorb small differences with packing or an extra profile, but the method should be agreed before production.

Obstacles inside the opening

Look for anything that interrupts the screen's path: gutters, lights, heaters, handrails, door handles, downpipes and cable runs. Note the position of each one and measure it from a fixed point. Any of these can change the mounting position.

How to Check Fixing Surfaces and Space

Size alone is not enough for a quotation.

Describe what the screen is fixed to

State the material of each fixing surface, such as aluminium, steel, timber, concrete or masonry, and give the profile size for posts and beams. Note any cladding or insulation over the structure. This affects the fixing method.

Check the space for the cassette

The cassette needs room at the top of the opening, and its size varies with the system and the screen size. Measure the depth and height that are actually free, including under a beam or ceiling, and mention any existing roof, gutter or roller system in the way. Ask for the cassette dimensions for your specific size instead of assuming them from another product.

Plan power and control for motorised screens

For motorised systems, mark where the power will come from at each screen and which side you prefer for the cable. Say too whether screens should be grouped, so a whole terrace can be operated together. Control options are confirmed per project.

What Should You Send to the Manufacturer?

Build an opening schedule

Give each opening a code, such as T1 or T2, and use it everywhere. The same code then follows the screen through the quotation, production, packing labels and installation. A simple schedule is enough:

To choose the fabric column, see our guide to zip screen fabric openness.

Add photos and a sketch

Take one photo of the whole opening and close-ups of each corner, with the opening's code visible. Add a simple sketch showing which side is left and right as seen from a stated position, inside or outside. Otherwise, "left" can mean opposite things to the person measuring and the person reading.

Know what depends on accurate sizes

Screen prices depend on size, fabric, operation and quantity, so rough sizes can give only a rough budget. Each screen is also cut for its own opening, so a wrong measurement can mean remaking a screen, plus a second shipment if it was exported. Use early estimates for budgeting, then re-measure the finished structure before confirming production.

How We Work From Your Measurements

LuxiVeil is the export brand of Gökcan Home, a curtain and blind manufacturer producing in Antalya, Türkiye, since 1994. We make zip screen blinds to measure in our own workshop, with no standard stock sizes. We do not publish general maximum sizes or wind classes, because these depend on the opening, the mounting and the exposure of the site. We review each opening in your enquiry and confirm in the quotation what can be produced.

Pergola and awning companies usually measure and install for their own customers while we handle production. Our supplier guide for pergola and awning companies explains that way of working, and our wholesale blinds page covers trade terms. There is no fixed minimum order.

Frequently Asked Questions

Should I deduct anything from my zip screen measurements?

No, not unless the manufacturer asks you to. Send the actual readings and state the mounting position. The manufacturer can then apply the right allowances for its own system and avoid a double deduction.

Do I use the smallest width or the largest?

Record all three. For an inside fit, the smallest reading usually limits what fits, but the right production size depends on the system and how the channels are fixed. Leave that decision to the manufacturer.

Can I measure before the floor or cladding is finished?

You can for a budget quotation, but confirm the sizes against the finished surfaces before production. Tiles, decking and cladding all change the opening.

What if my opening is out of square?

Record the readings and the diagonals, then send photos of the corners. The manufacturer and installer can then decide on packing, an extra profile, a different mounting position or another solution before anything is cut.

Can one zip screen cover a very wide opening?

It depends on the system, the mounting and the exposure of the site. A very wide or high opening may be better divided into two screens. Send the sizes and we will check the opening and confirm the options in the quotation.

Does a pergola company need a site survey for every screen?

Each opening needs its own measurements, even when bays look identical, because small differences are common. Who takes them can vary, but the responsibility for them should be agreed before production.

Request a Quote or Samples

Send us your opening schedule or simply the readings for each opening, with the mounting situation, photos, your fabric and colour preference, the operation you want and the delivery address. We will review each opening, send fabric samples for approval and return a quotation per screen. Use the quote form on our contact page, or message us on WhatsApp for a quick first answer.