Buying Guides
How to Measure for a Zip Screen Without Ordering the Wrong Width
The three numbers that decide the order, why the opening is not the fabric width, and what to send to the mill so the roll is cut once.
By the technical team at Shandong Orenda New Materials Co., Ltd. Specification questions: jane@orendascreen.com. Published 11 November 2026.
The number you order is not the window
Almost every width problem in a zip screen order begins in the same place: someone measures the opening and orders fabric to that dimension. The fabric does not span the opening. It spans the channel-to-channel distance, plus the allowance the zip profile needs on each edge.
That allowance is a property of the system, not of the fabric. Two channel profiles from two suppliers can need different amounts, and a fabric cut to the wrong figure either will not tension or will not fit the track. So the first rule is simple: get the allowance from whoever supplies the channels, and keep it in writing.
Measure in this order
Work from the fixed side outwards. Measuring in this order means a mistake shows up before the fabric is cut.
- Identify the two mounting planes: the wall, reveal or frame the channels will fix to, and whether either side is out of plumb.
- Measure the channel-to-channel distance at the top, the middle and the bottom. On a rendered or masonry reveal these three will differ.
- Take the narrowest of the three. The fabric has to clear the tightest point, not the average.
- Add the zip allowance from the system supplier to get the fabric width.
- Measure the finished drop from the headrail underside to where the bottom bar sits when the screen is closed, not to the floor.
Write down all six figures even when you only need the minimum, because a difference between top and bottom tells you the reveal is not square, and that is a conversation to have before the order rather than after.
Where the fabric width limits land
Our fabric is woven in five widths: 1600, 1900, 2500, 2850 and 3200 mm. Every colour in the range is available in all five, so colour never forces a seam.
What changes with width is roll length. The 1600, 1900 and 2500 mm widths come on 50 m rolls, 2850 mm on 40 m and 3200 mm on 33 m. For a single domestic screen that matters little. For a facade with many drops it changes how you plan the cut list, because a 3200 mm roll carries a third less linear metres than a 1600 mm roll of the same weight.
A practical consequence: if the channel-to-channel distance plus allowance comes to 2900 mm, you order the 3200 mm width. You do not try to squeeze it from 2850 mm, and you do not accept a 40 mm join to save money, because a horizontal join in a vertical drop is visible in raking light.
What to send with the enquiry
The mill cannot verify your measurement, but it can cut to the figure you give. What it can do is tell you whether that figure is producible, and whether the drop and the roll length line up.
Send these five items:
- Channel-to-channel distance, and the narrowest of your three readings
- Zip allowance, or the name of the channel profile so the allowance can be looked up
- Finished drop
- Colour code, not the colour name, because names repeat across the range
- Fire standard the project has to meet, if any
That is enough to confirm availability and cut the roll once.
Three mistakes worth naming
**Ordering the opening.** The opening is the size of the hole in the building. The fabric is the size of the closed screen. They differ by the channel depth and the zip allowance on both sides, which is often 40 to 70 mm in total.
**Averaging an out-of-square reveal.** If the top measures 2410 mm and the bottom 2440 mm, the fabric is cut to 2410 mm plus allowance. Cutting to the average leaves the screen slack at the top and tight at the bottom, and the screen will track to one side.
**Quoting a colour name instead of a code.** Two colours in the range share the name charcoal-caramel and carry different codes. The code is what goes on the production sheet; the name is a description.
Measure the channel, add the allowance, take the narrowest reading, and write all of it down. The cutting room can only be as accurate as the number it is given.
If the screen is already made
If a screen tracks to one side or will not tension, the cause is usually the edge rather than the weave. A cut edge that has shed filaments will jam the zip, and a fabric cut wider at one end than the other will pull unevenly no matter how the channels are set.
Our fabric is dip coated, so the PVC is carried through each yarn rather than applied to the surface. A crush or ultrasonic cut leaves an edge that does not fray, which is why we recommend those two methods over a knife. If your workshop cuts in house, tell us which method it uses when you order.
What the fabric itself can take
A zip screen holds the fabric in tension across its full width, so a specifier usually asks how much load the cloth takes. SGS tested the fabric to ISO 1421:2016 Method 1, the strip method, on a black sample: 2520 N in the warp direction and 3263 N in the weft, report SL42604345745501TX. Weft is the stronger direction because of the weave density.
Read that as a material property, not a design load. The load on a finished screen depends on the tension the system applies, the drop, the wind zone and the fixings, and the system supplier rates the assembly. What the figure tells you is the relative margin: the weft carries roughly 29% more than the warp, which is why a zip running along the weft edge behaves differently from one running along the warp.
The tensile test was carried out on the 3% construction. No tensile test has been run on the 5% range, so no figure is published for it — the two are different weaves and the result should not be read across.
Questions that come up before the order
What if my channel-to-channel distance falls between two fabric widths?
Go up to the next width. Our fabric is woven at 1600, 1900, 2500, 2850 and 3200 mm, and there is no intermediate size. A distance of 2600 mm plus allowance is ordered at 2850 mm, not 2500 mm. Going up also means the roll length changes at the two widest options, so check the cut list if the project has several drops.
Do you supply the zip and the side channels?
We supply the fabric only. Zips and channel systems come from the system suppliers, and the allowance you add to your measurement has to come from whoever supplies those channels, because it varies by profile. Ask them for the figure in writing and pass it on with the order.
Can the fabric be cut on site if the measurement turns out wrong?
It can be cut, but the edge quality decides whether the screen will run. A crush or ultrasonic cut seals the edge; a knife or a worn blade leaves protruding filaments that jam the zip. If the site cut is unavoidable, use a sharp blade and finish the edge, and expect the screen to need re-tensioning.
Does the fabric shrink or stretch after installation?
We do not publish a shrinkage or elongation figure for this fabric, so we cannot give you a percentage. Fibreglass is a low-stretch yarn and the dip coating adds dimensional stability, which is why the construction is used on long drops, but if a project has a specified dimensional tolerance, tell us the figure and we will say whether we can support it.
What information should go on the purchase order?
Five items: the colour code rather than the colour name, the fabric width you need (not the opening), the finished drop, the quantity in rolls or linear metres, and the fire standard the project has to meet. The colour code is what the production sheet is written against.
Sources
[S1] SGS, test report SL42604345745501TX, dated 2 September 2026. Tensile strength to ISO 1421:2016 Method 1 (strip method), 2520 N warp / 3263 N weft. Sample: black. Report available on request.
[S2] Orenda product specification, 3% and 5% openness PVC-coated fiberglass sunscreen fabric. Weights, thickness, widths and roll lengths as published on the product pages of this site.
No third-party data is used in this article. The five widths, the roll lengths and the fire reports are our own supply-chain facts and are stated as such.
