FIRST
What this page is, and is not
The authoritative instructions for any product are the manufacturer's, supplied with the unit and published on its product page under Installation. Follow those. They are what the warranty is written against.
This page is the layer around them: what to have ready, what to check before you start, and the handful of things that go wrong often enough to be worth naming. It is general guidance for competent installers, not a method statement, and it does not replace your roofing specification.
We supply products. Installation is carried out by your roofing contractor.
BEFORE YOU START
The checks that save a second visit
On the ground, not on the roof
- 1 Check the article numbers on what arrived against the order. Descriptions can match when products do not.
- 2 Open and inspect before you go up. A defect found on the ground is a phone call; the same defect found on the roof is a wasted lift.
- 3 Read the installation document for this unit, not the one you remember from last time. Build-ups and fixing details differ between lines.
- 4 Confirm the upstand and the unit are a matched pair — right nominal size, right type, right height for the finished build-up.
- 5 Check the opening is square, or know by how much it is not. The smaller dimension governs.
- 6 Have the flashing or membrane detail agreed with whoever is responsible for the waterproofing, before the opening is exposed.
THE SHAPE OF THE JOB
What the sequence normally looks like
Detail varies by product and by roof. This is the order the decisions come in, not a substitute for the instructions.
| Stage | What matters |
|---|---|
| Opening prepared | Square, correct clear dimensions, structurally sound edges |
| Upstand set out and fixed | Fixed to the deck per the instructions, sitting level, correct height above the finished surface |
| Insulation and waterproofing | Dressed up the upstand and terminated per the roofing specification — this is the roofer's detail, not ours |
| Unit seated | Onto the upstand flange, bedded and fixed per the instructions. No trimming, no drilling |
| Opening gear | Where the unit ventilates, fitted and tested before you leave the roof |
| Final check | Operation, seating, flashing dressed, and a photograph of the finished installation |
The waterproofing termination is where most rooflight leaks originate, and it is the one stage that is not a rooflight question.
COMMON PROBLEMS
What goes wrong on site
The unit does not seat on the upstand
Almost always a size or type mismatch rather than something to adjust. Stop, measure the internal opening at the top of the kerb in both directions, and send it with a photograph. Do not trim the flange — modifying the unit ends the warranty on it, and if it is the wrong item we will replace it.
The upstand is too short once the build-up is on
This is a different upstand, not an adjustment. The height needed is measured from the finished roof surface, and if it was worked out from the deck it will be short by the depth of the insulation and waterproofing. Packing it up is not a fix.
The opening is out of square
Common on site-cut openings. The smaller dimension governs what will fit. If the difference is significant, send both figures before ordering rather than discovering it with the unit on the roof.
Water is coming in after installation
Check the flashing and the membrane termination before suspecting the unit. Water tracking in at the edge is a roofing detail in most cases, and replacing the rooflight will not fix it. Photograph the junction from above and the ingress from below.
Condensation appears after fitting
Condensation between the shells means a failed seal, and that is the unit. Condensation on the inside face is usually the room — humidity and ventilation — or a cold bridge around the opening, which points at the upstand or the insulation detail rather than the glazing.
The opener will not hold position
Usually the actuator, which can often be replaced on its own rather than replacing the whole unit. Send the article number of the unit and we will identify the part.
PROTECT THE COVER
Three things that end the warranty
Modifying the unit. Cutting, drilling, trimming a flange to make something fit. If it does not fit, it is the wrong item.
Fitting to an unsuitable upstand. A unit on a kerb it was not designed for is not a warrantable product failure, whatever happens next.
Departing from the instructions. Where the roof genuinely requires a different approach, agree it in writing beforehand rather than explaining it afterwards.
Two minutes of paperwork protects all three: keep the invoice and the article number, and photograph the completed installation before you leave. Full terms are on the warranty page.
WHERE THE DOCUMENTS ARE
Finding the right instructions
- Installation documents by productOn each product page, under the Installation tab
- Downloads libraryEverything in one place, filterable by range
- Choosing an upstandTypes, the height grid, and fitting to an existing kerb
- Roofers & installersOrdering from site and checking a delivery
Stuck mid-installation?
Photograph it and send it with the article number. Site queries get answered faster from a picture than from a description.
General guidance for competent installers. It does not replace the manufacturer's installation instructions or your roofing specification, and decisions about access and working at height are for the contractor carrying out the work.