START HERE
What is on the roof already?
Three situations, three different answers. Find yours first — it decides everything else on this page.
Nothing there yet
DOME + UPSTAND
A new opening needs both parts. Order them together so the sizes match and they arrive on the same delivery.
- Pick the rooflight first
- The upstand selector on that page only offers heights that exist
- Both lines ship as one order
Use it when you are cutting a new opening, or replacing a unit and its kerb together.
A Kingspan upstand
DOME ONLY
If the existing upstand is sound and Kingspan, you can usually keep it and replace only the dome.
- Find the article number on the upstand label
- Check the internal opening still matches the nominal size
- Check the flange and fixing holes are undamaged
Use it when the kerb is in good condition and you know the article number.
Someone else's upstand
SEND MEASUREMENTS
It may still fit. Kerbs from other manufacturers vary in internal opening and flange width, so this one we check rather than guess.
- Measure the internal opening at the top of the upstand, both directions
- Measure the flange width and the upstand height
- Photograph it with a tape measure in shot
Use it when you are replacing a dome on a kerb we did not supply.
Send it to us and we will confirmBACKGROUND
What the upstand is doing
An upstand is the kerb the rooflight sits on. It is not a spacer — it is doing four jobs at once, and each one is a way the detail can fail.
It lifts the glazing above standing water. A dome bedded straight onto the deck sits in whatever the roof does not drain.
It gives the membrane something to turn up. The roofing contractor needs a vertical face to dress the waterproofing against and terminate it.
It carries the insulation line past the opening. An uninsulated kerb is a cold bridge around all four sides of the hole, and that is where condensation shows up first.
It gives the dome something to fix to. The flange, the fixing centres and the clamping are designed as a pair with the rooflight above them.
Which is why the upstand is chosen before the dome, not after it.
THE RANGE
Three types
Pick the type first. The heights available change with the type, so choosing the other way round leads to combinations that do not exist.
AK PVC
15 · 30 · 50 CM
Insulated PVC kerb. Light enough to handle on a roof without a lift, and the widest choice of heights.
- Three heights, so it suits most flat-roof build-ups
- Lightest of the three to get up and set out
- The default unless the specification says otherwise
Use it when standard flat-roof refurbishment and new openings with no special loading requirement.
AK ST
30 · 40 · 50 CM
Steel kerb. Specified where the detail calls for a steel upstand rather than PVC.
- The only type with a 40 cm height
- Used where the roof specification names a steel kerb
- Heavier — plan how it gets onto the roof
Use it when the specification names a steel upstand, or the deck detail requires one.
AK ST-TG
50 CM ONLY
Steel with a thermal break, for details where the kerb must not bridge the insulation line.
- One height only — 50 cm
- Use where the thermal detail is being calculated
- Lead time can differ from the other two
Use it when the thermal performance of the whole opening is being assessed, not just the glazing.
AVAILABILITY
Which heights exist
Not every type is made in every height. This is the whole grid.
| Type | 15 cm | 30 cm | 40 cm | 50 cm |
|---|---|---|---|---|
| AK PVC | Yes | Yes | — | Yes |
| AK ST (steel) | — | Yes | Yes | Yes |
| AK ST-TG (thermal break) | — | — | — | Yes |
The upstand selector on each rooflight page is built from this grid, so it will not offer you a height that does not exist. If you need a height that is not listed, ask — it becomes a quote rather than an online order.
Height is measured as the upstand itself, not the finished detail. What matters on site is how much of it stands proud of the finished roof surface once the insulation and the waterproofing are on — flat-roofing practice generally wants a meaningful upstand above that finished level, and your roofing specification will state the figure it expects.
So the sum is: deck to finished surface, plus the height your roofing detail requires above it. Then round up to a height the type actually comes in.
ON SITE
How to measure
Six minutes with a tape
- 1 Measure the clear opening in the roof deck, inside edge to inside edge, in both directions.
- 2 Measure it again at the other end — openings cut on site are rarely square, and the smaller figure is the one that counts.
- 3 Match that to a nominal size. You order by nominal size, not by the outside dimension of the dome.
- 4 Measure from the structural deck up to the finished roof surface, including the insulation and the waterproofing.
- 5 Add the upstand height your roofing specification wants above the finished surface. That total tells you which height to buy.
- 6 Photograph the opening with the tape in shot before you order. If anything is ambiguous later, that photo settles it in one message.
IMPORTANT
SR is not fall-through protection
ORDERING
How it appears on the order
Choose the upstand on the rooflight page and it is added as its own line, under its own Kingspan article number. You will see two lines in the basket: the rooflight and the upstand. That is correct — they are two products, they are picked and packed as two products, and the article numbers are what the factory works from.
Occasionally a type and height combination cannot be ordered online. When that happens the page says so and offers to put it on a quote instead of failing quietly. Send it through and it comes back priced.
QUESTIONS
Common questions
Can I fit a Kingspan rooflight to another manufacturer's upstand?
Sometimes. It depends on the internal opening at the top of the kerb, the flange width and the fixing arrangement. Send us those three measurements and a photograph and we will tell you either way. We would rather check than have you find out on the roof.
Can the rooflight sit straight on the deck without an upstand?
No. The units in this range are designed to be mounted on an upstand — it is what carries the waterproofing detail and the fixing. If your opening already has a builder's kerb formed in timber or concrete, send the details and we will look at it as a specific case.
I am only replacing the dome. Do I need a new upstand?
Not if the existing one is Kingspan, sound, and the right nominal size. Check the article number on the label, check the flange and fixing points are undamaged, and check nothing has moved. If the label has gone, measure the internal opening and send it over.
Which height should I pick?
Work from the finished roof surface, not the deck. Measure the build-up — deck, insulation, waterproofing — then add the upstand height your roofing specification requires above that finished level. Round up to a height the type is made in.
Why does the height list change when I change the type?
Because the ranges are genuinely different. PVC comes in 15, 30 and 50 cm; steel in 30, 40 and 50; the thermally broken steel in 50 only. The selector hides combinations that do not exist rather than letting you order one that cannot be supplied.
Do you supply upstands on their own?
Yes. If you are phasing the work, or the kerb goes in ahead of the glazing, order the upstand by itself. Send us the rooflight it will eventually take so we can check the pairing now rather than later.
Send us the opening.
A photograph with a tape measure in shot, plus the two internal measurements, is usually all we need to tell you what fits.
Availability and designations follow current Kingspan Light + Air documentation. Where your roofing specification differs from the general guidance on this page, follow the specification.