Updated: 23 September 2026 · EuroVan Shop
In short: Caravan skylight replacement starts with one measurement: the opening in the roof, not the old outer frame. Most use a classic cut-out: 400 × 400, 700 × 500 or 960 × 655 mm. Pick a skylight made for that cut-out and your roof thickness, remove the old one, clean off the old sealant and bond the new one with the Sikaflex skylight pack. See our replacement skylights.
Find your replacement skylightWhen should you replace a caravan or motorhome skylight?
Replace the skylight when the roof light itself is failing: a cracked or crazed dome, acrylic that has turned yellow and brittle, broken hinges or gas struts, or a frame that no longer closes. Reseal it instead when the dome is sound and water only gets in along the edge of the frame.
This is a common job on a used caravan or motorhome. Roof lights sit in full sun all year, and the original sealant ages with them. The good news: you do not need to cut the roof. As long as you choose a skylight made for the same cut-out, the new one drops into the existing opening.
For the classic motorhome sizes, go straight to our replacement skylights in Heki-format cut-outs. For the small square roof light found on many caravans, see our 40 × 40 caravan skylights.
How do you measure a caravan skylight?
Measure the opening cut in the roof, not the outer frame of the old skylight. The outer frame is always larger than the hole and varies from brand to brand, so it tells you nothing about which replacement fits. Every size we list is the cut-out size.
- From inside, remove the inner frame (the blind and fly-screen cassette). It is usually held by screws around the edge.
- Measure the hole: width and length, in millimetres, edge to edge of the roof opening.
- Measure the roof thickness: from the outer roof skin to the inner ceiling panel, at the edge of the opening. The new skylight must be made for that thickness.
- Note the roof type: flat or corrugated. A corrugated roof needs butyl tape to fill the ridges.
- Take a photo of the opening with a tape measure in the shot. If in doubt, send it to our team.
Old openings are rarely cut to the millimetre: a reading of 398 or 402 mm probably means the standard 400 mm cut-out. Send us a photo and we will confirm.
Which replacement skylight fits your cut-out?
Match the cut-out first, then check the roof thickness. The three classic formats below cover most motorhome and caravan roof lights, and each has an EuroVan Shop model made for the same opening.
| Roof cut-out | Classic format | Our replacement | Roof thickness |
|---|---|---|---|
| 400 × 400 mm | Mini Heki format | STYLE 40x40 (with or without 100 cm² permanent ventilation) | 28 to 70 mm |
| 400 × 400 mm | Mini Heki format, with 12 V fan | VANVENT 3.0 or EuroVan 40x40 roof vent fan | 27 to 80 mm / 25 to 60 mm |
| 700 × 500 mm | Midi Heki format | PANORAMA SLIM 3 LED 700 × 500 | 25 to 70 mm |
| 700 × 500 mm | Midi Heki format | PANORAMA LED 500x700, clear or GREY | 25 to 75 mm, more with a spacer |
| 960 × 655 mm | Heki 2 and Heki 3 format | PANORAMA SLIM 3 LED 960 × 655 | 25 to 70 mm |
| 500 × 500 or 800 × 500 mm | Other skylights with these cut-outs | PANORAMA SLIM 3 LED in that size | 25 to 70 mm |
Check that the new outer frame covers the marks left by the old one. The PANORAMA SLIM exterior measures 780 × 580 mm on the 700 × 500 size and 1040 × 730 mm on the 960 × 655 size. On the STYLE 40x40, allow up to 130 mm more in width and 110 mm more in height for the interior frame.
Heki is a trademark of Dometic. EuroVan Shop does not sell Heki products: our roof windows carry their own names and fit the same roof cut-outs.
PANORAMA SLIM 3 LED 700 x 500
Midi Heki-format cut-out, 6 cm above the roof, 166 cm² permanent ventilation, LED, blind and fly-screen.
PANORAMA SLIM 3 LED 960 x 655
Heki 2-format cut-out, aluminium frame, about 226 cm² permanent ventilation. ECE R43.
STYLE 40x40
400 × 400 mm cut-out, double acrylic glazing, blackout blind and fly-screen, LED frame optional.
What do you need to replace a motorhome skylight?
You need the new skylight, the Sikaflex skylight pack, a cartridge gun and basic hand tools. No jigsaw is needed when you keep the same cut-out.
- Sikaflex skylight pack: Sikaflex 552 AT adhesive sealant (300 ml, white), Sika Aktivator 205, SikaPrimer 507 and SikaLastomer 831E butyl tape.
- A cartridge gun, a lint-free cloth for the Aktivator 205 and a brush for the Primer 507.
- Screwdrivers or a cordless driver, a plastic scraper and masking tape.
- A second person: plan for two people to lower a PANORAMA skylight into the opening.
- A 12 V feed and fuse if you switch to a fan or a model with LED lighting.
Pick a dry, mild day and work from a stable platform. Only stand on the roof if the manufacturer says it can take your weight.
Sikaflex Skylights Pack
Sikaflex 552 AT, Aktivator 205, Primer 507 and 831E butyl tape: everything to bond one skylight.
How do you remove the old skylight?
Remove the inside first, then free the outer frame from the roof by cutting through the old sealant. Take your time: the aim is to lift the roof light without tearing the roof skin.
- Inside: unscrew and remove the inner frame, blind and fly-screen cassette. Disconnect any wiring to a light or fan, with the 12 V supply switched off.
- Fixings: remove the screws that clamp the skylight to the roof. On many roof lights they are hidden under the inner trim.
- Break the seal: from outside, work a plastic wedge or scraper under the edge of the frame and cut through the sealant bead all the way round. Avoid metal blades near an aluminium or GRP roof skin.
- Lift it out straight up, with a helper holding it from above.
- Inspect the opening: if the wood or foam around the hole is soft, dark or damp, dry it out and repair it before you go further.
How do you clean off the old sealant?
Remove every trace of old sealant, down to a clean, sound roof surface. New Sikaflex will not bond properly over old sealant, silicone, dust or grease, and poor preparation is the most common reason a skylight leaks again.
- Scrape the bulk off with a plastic scraper, working along the old bead rather than across the roof.
- Take off the thin residue last, without scratching through paint or gelcoat.
- Wipe the area with a lint-free cloth and Sika Aktivator 205 to clean and prepare the surface.
- Let it dry, then mask off around the new frame outline for a tidy finish.
If the old roof light was bedded in silicone, be especially thorough: silicone residue stops most adhesives from gripping.
How do you fit the new skylight with the Sikaflex skylight pack?
Prepare the surface, fill the ridges if the roof is corrugated, lay a continuous bead of Sikaflex 552 AT, then lower the skylight in and fix it from inside. That is the order given with our Sikaflex skylight pack.
- Dry fit: set the new skylight in the opening without sealant to check the fit and the roof thickness. Mark the outline.
- Activate: wipe the bonding area with Aktivator 205 on a lint-free cloth.
- Prime: brush SikaPrimer 507 where the substrate requires it and respect the flash-off time in Sika's instructions.
- Corrugated roof only: fit SikaLastomer 831E butyl tape to fill the ridges under the frame.
- Bond: run one continuous bead of Sikaflex 552 AT around the frame, with no gaps at the corners.
- Lower and fix: lower the skylight in, press it down evenly, then fit the inner frame and screws from inside following the skylight's fitting guide.
- Finish and cure: smooth the squeeze-out, remove the masking tape and avoid washing or heavy stress before the curing time stated by Sika.
Our skylight installation guide covers new cut-outs, and our Sikaflex guide explains each product.
Get the Sikaflex skylight pack
How do you fix a leaking caravan skylight?
Find where the water gets in first. If the dome is intact and the water comes in around the frame, the skylight only needs resealing. If the dome is cracked or crazed, or the frame is warped, resealing will not last and the roof light should be replaced.
| What you see | Likely cause | What to do |
|---|---|---|
| Drips along the edge of the inner frame, dome intact | Aged or broken sealant bead | Remove, clean and re-bed the frame |
| Water only when the roof light is open | Worn rubber seal or a hinge that no longer pulls the dome shut | Check the seal and hinges; replace the roof light if parts are broken |
| Hairline cracks, crazing, yellow brittle acrylic | UV-aged dome | Replace the skylight |
| Soft or stained ceiling around the opening | Water getting into the roof structure | Remove the skylight, dry and repair the roof, then refit |
A proper reseal means lifting the frame, cleaning off the old sealant and bonding it again, which is the same work as fitting a new skylight. If your roof light is old and yellowed, that is usually the moment to replace it. Resealing a joint without removing the frame only covers the problem for a while.
Can you swap an old roof light for a fan or a larger skylight?
Yes. In the same 400 × 400 mm cut-out you can fit a 12 V roof vent fan instead of a plain roof light, and the only extra work is running a fused 12 V feed. The VANVENT 3.0 has a 450 × 593 mm outer flange that covers the marks left by an older vent of the same size.
Going from a small roof light to a larger one means enlarging the cut-out. Check first that no roof crossmember runs through the new outline. Our 12 V roof fan guide compares the fans, and our skylight buying guide compares every roof window.
VANVENT 3.0 GREY
400 × 400 mm, brushless 12 V fan, 10 speeds, thermostat, radio remote, LED, blind and fly-screen.
EuroVan 40x40
400 × 400 mm, reversible 12 V fan at 1200 RPM, fly-screen, usable in the rain with the lid closed.
PANORAMA LED 500x700
Midi Heki-format cut-out, 150 cm² permanent ventilation, LED, blind and fly-screen.
Not sure which roof window fits your roof?
Send us the cut-out size and roof thickness (or a photo). Our France-based technical team answers within 24 hours.
Ask our technical teamFrequently asked questions
How do you measure a caravan skylight?
Remove the inner frame and measure the hole in the roof, width and length in millimetres, not the outer frame of the old skylight. Also measure the roof thickness at the edge of the opening and note whether the roof is flat or corrugated.
Where can I find a replacement skylight for my caravan or motorhome?
EuroVan Shop sells roof windows made for the classic cut-outs: 400 × 400 mm (STYLE 40x40, VANVENT 3.0, EuroVan 40x40), 700 × 500 mm (PANORAMA SLIM, PANORAMA LED) and 960 × 655 mm (PANORAMA SLIM). Send us your measurements if you are unsure.
Can I replace a Mini Heki or Midi Heki with a different brand?
Yes, as long as the new skylight is made for the same cut-out and your roof thickness. Our STYLE 40x40 fits the 400 × 400 mm Mini Heki format, and the PANORAMA SLIM 700 × 500 and PANORAMA LED 500x700 fit the Midi Heki format. Heki is a trademark of Dometic.
Which sealant should I use to refit a skylight?
Sikaflex 552 AT, with Sika Aktivator 205 and Primer 507 to prepare the surface and SikaLastomer 831E butyl tape on a corrugated roof. All four are in our Sikaflex skylight pack.
Is resealing enough for a leaking skylight?
Only if the dome is intact and the water enters around the frame. Cracked, crazed or yellowed acrylic, broken hinges or a warped frame mean the skylight should be replaced.
Do I need approval to replace a skylight?
Rules differ by country, so check your national rules (DVLA, TÜV or RDW). Our STYLE 40x40, PANORAMA and VANVENT roof windows are ECE R43 approved.
Measured your cut-out? Pick the skylight made for the same opening.
Shop replacement skylights
