A ceiling zip screen is a shading system that runs on a horizontal rather than a vertical axis. The fabric moves back and forth along aluminium rails on either side and stays locked inside the rail thanks to the zip strip on its edges. Its most common application is beneath glass roofs, where it meets the solar radiation passing through the glass close to the source and cools the space below. In this article we look at how the system works, which problem it solves and what matters for a correct installation.
The problem it solves is clear: the greenhouse effect. Glass lets solar radiation through; the surfaces beneath warm up and the long-wave heat they radiate cannot escape back through the glass. The result is a temperature that climbs quickly under a glass roof in summer. Left unaddressed, this effect makes a winter garden or a glass-roofed terrace unusable in summer. A ceiling zip screen breaks that chain by intercepting the radiation just below the glass surface.
Whether the shading sits on the inside or outside of the glass matters. External shading is thermally more effective because it stops the radiation before it reaches the glass. But in an external application the system is directly exposed to wind, rain, snow and dirt, so the cassette and fabric must be exterior grade and work together with a wind sensor. Internal shading is sheltered, lasts longer and is easier to maintain; although its thermal effect is slightly lower, it makes a clear difference in glare control and comfort.
The mechanics follow the same logic as a vertical zip screen. The zip strip welded to both fabric edges enters the channel inside the side rails and stays locked there. The difference is that gravity works against the system rather than for it: in a vertical blind the bottom bar keeps the fabric taut by its own weight, while in a horizontal screen a separate tensioning solution is needed to stop the fabric sagging. That is usually provided by a spring tensioning mechanism or by intermediate support profiles.
Sagging is the most visible indicator of quality in a ceiling zip screen. As the span grows, so does the fabric's tendency to droop in the middle; in an inadequately tensioned system that sag is both visually unsatisfying and leads to permanent deformation of the fabric over time. For wide spans, therefore, several modules are used rather than a single screen, with an intermediate profile between them. In a properly modularised system the fabric stays even for years.
Fabric choice determines how much work the system does. Micro-perforated screen fabrics filter light, lower the temperature and shade the space without darkening it completely; a natural brightness is preserved beneath the glass. The lower the openness factor, the stronger the shading. Fabrics with a silver or light-coloured backing reflect solar radiation and noticeably improve thermal performance, which is particularly valuable in ceiling applications.
Blackout fabric, by contrast, blocks light entirely. It is chosen in spaces where a projector is used, under glass roofs facing sleeping areas, or wherever full darkness is needed. It is the option with the highest thermal effect; but if the purpose of the glass roof is daylight, blackout fabric removes that purpose. In most projects it is therefore used only on the section where it is needed, not across the whole surface.
Glare control is as important as temperature but discussed less. Direct sun through a glass roof makes screens hard to read, causes eye fatigue and leads to fading on furniture and textile surfaces. Screen fabric diffuses the light without blocking it, softening that harsh contrast. In restaurants, offices and showrooms, this is usually where a ceiling zip screen makes the greatest difference.
Automation becomes almost a necessity rather than a comfort in ceiling zip screens. The temperature beneath a glass roof changes quickly through the day with the sun's angle. A sun sensor closes the screen automatically once light intensity passes a set threshold, intervening before the heat builds. A time schedule can be set for automatic closing around midday. In external applications a wind sensor is a safety component; the system retracts automatically once the set speed is exceeded.
A ceiling zip screen is not the only complement to a glass roof. Ventilation from the sides must also be planned, because the screen intercepts radiation but does not remove warm air that is already inside. With guillotine glass or sliding glass, the upper section can be opened to let accumulated warm air out. When shading and ventilation work together, the space under a glass roof stays comfortable through summer too.
The applications are not limited to glass roofs. Beneath a bioclimatic pergola it can be used to soften the light coming between the louvres and produce a more even shade. In rooms with high ceilings it acts as a second ceiling, reducing the volume that needs heating. On wide glass façades it can also be installed to run on a sloped rather than a horizontal axis; the system then moves parallel to the slope of the glass surface.
Size limits and modularisation should be decided at the start of the project. As width grows, so do the load on the fabric and the tendency to sag; here it is the span, not the height, that decides. Cassette diameter is chosen according to the length of fabric to be wound. If the supporting beams of the glass roof are planned from the outset to accommodate the fixing points of the screen rails, the result is both stronger and cleaner; that is why we recommend engineering the glass roof and ceiling zip screen together.
On maintenance the system asks little attention, but not none. When dirty, the fabric is cleaned with warm water and a pH-neutral soap using a soft brush; pressure washing and bleach must not be used. Dust collecting in the channel inside the side rails makes the zip strip harder to move, so cleaning that part regularly extends system life. In external applications the fabric should not be left retracted while wet for long periods.
The technical items to check when deciding are these: the fabric's openness factor and backing reflectivity, the type of tensioning mechanism, how many modules the span will be divided into, the rail profile section and the depth of the zip channel, cassette diameter, motor brand and whether sensors are included. We particularly suggest asking for the sag tolerance to be stated in writing in the quotation.
In summary, a ceiling zip screen meets the greenhouse effect of a glass roof at its source, softens glare, and scales from shading to full blackout depending on fabric choice. For the right result the tensioning solution and modularisation must be planned from the start, the fabric chosen for the façade orientation, and the whole set up together with ventilation. You can review our ceiling zip screen systems, and read about our glass roof solutions in this article.
To settle on the right ceiling zip screen setup for your glass roof, request a free site survey.
Frequently Asked Questions
It intercepts the solar radiation passing through a glass roof just below the glass; it reduces the greenhouse effect, softens glare and noticeably cools the space beneath.
Yes, but as the span grows so does the fabric's tendency to sag. Wide surfaces are solved with several modules rather than a single screen, with an intermediate profile between them.
Screen fabric if you want to keep natural light; blackout if full darkness is required. If the purpose of the glass roof is daylight, blackout removes that purpose.
