Updated: 23 September 2026 · EuroVan Shop
In short: For campervan windows, use Sikaflex 265 with Sika Aktivator 205 and Primer 507 to prepare the surface: one tube per window. For roof windows and skylights, use Sikaflex 552 AT, plus SikaLastomer 831E butyl tape to fill the ridges of a corrugated roof. Use Sikaflex 522 for sealing joints, vents and cable glands.
See campervan windowsWhich Sikaflex should you use for campervan windows?
Use Sikaflex 265 for campervan windows, with Sika Aktivator 205 and SikaPrimer 507 to prepare the bodywork. It is the adhesive sealant specified for every EuroVan window in our campervan windows range. Roof windows are a different job: our roof windows are fitted with Sikaflex 552 AT.
| Job on a van, motorhome or caravan | Product | Why |
|---|---|---|
| Fitting a side or rear-door window | Sikaflex 265 + Aktivator 205 + Primer 507 (Window Kit) | Bonds and seals glazing; the 205 and 507 prepare metal and paint |
| Fitting a roof window or skylight | Sikaflex 552 AT, alone or in the Skylights Pack | The adhesive sealant specified for our roof windows |
| Skylight on a corrugated roof | SikaLastomer 831E + Sikaflex 552 AT | The butyl tape fills the ridges of the roof |
| Sealing joints, vents, cable glands | Sikaflex 522 | Flexible, weather- and UV-resistant sealant |
| Bonding exterior parts exposed to vibration | Sikaflex 552 AT | Adhesive sealant for demanding exterior mounts |
| Preparing the surface before bonding | Sika Aktivator 205, SikaPrimer 507 | Improves adhesion on smooth or difficult surfaces |
The logic in one line: a sealant does not replace a glazing adhesive, and a strong adhesive is not the right choice for a part you may want to remove later.
Why is Sikaflex 265 the right choice for van windows?
Sikaflex 265 is a polyurethane adhesive sealant made for bonding and sealing windows in motorhomes and campervans. It bonds directly to glass without primer, resists UV, weather and ageing, and is solvent-free, PVC-free and low odour, so it is also pleasant to use indoors.
On a EuroVan window, the aluminium counter-frame clamps the window mechanically; the 265 bonds the frame to the bodywork and keeps water out. On the curved wall of a panel van it also fills the small gap between the flat window and the curve.
Around the window, the bodywork is painted metal, not glass. That is why the Sikaflex Window Kit adds Sika Aktivator 205 and SikaPrimer 507: they prepare metal, plastic and painted surfaces for a durable bond. The kit contains one 300 ml cartridge of 265, 30 ml of Aktivator 205 and 30 ml of Primer 507. Add a cartridge gun, a lint-free cloth for the 205 and a brush for the 507. See our step-by-step fitting guide for the full method.
Sikaflex Window Kit
Sikaflex 265 + Aktivator 205 + Primer 507: everything to bond one window.
Sikaflex 265 black, 300 ml
Window adhesive sealant, by the unit or by the dozen.
Sika Aktivator 205, 250 ml
Large bottle of surface pretreatment for several windows.
Which Sikaflex for roof windows and skylights?
Use Sikaflex 552 AT for roof windows and skylights. It is the adhesive sealant we specify for our STYLE 40 × 40, SKYDOME 40 × 40 and PANORAMA roof windows, either on its own or in our Skylights Pack.
On a corrugated roof, the ridges leave gaps under a flat skylight frame. SikaLastomer 831E, a grey butyl sealing tape (3 mm × 12 mm, 12 m roll), fills those ridges so the skylight sits on an even, sealed base. The Skylights Pack brings together the 552 AT adhesive, the 831E butyl tape and the cleaner and primer, so nothing is forgotten.
Choose the pack if you are fitting a skylight and want a complete, consistent kit. Choose the 552 AT alone if you already have your preparation products.
Sikaflex Skylights Pack
Sikaflex 552 AT + SikaLastomer 831E butyl tape, with cleaner and primer.
SikaLastomer 831E
Grey butyl sealing tape, 3 × 12 mm, 12 m. Fills corrugated roof ridges.
When do you need SikaLastomer 831E butyl tape?
You need SikaLastomer 831E when a skylight goes on a corrugated roof, or when you want a compressed seal that can be removed later. As the frame is tightened, the butyl tape compresses and fills the irregularities between skylight and roof.
Butyl is there to seal, not to hold a loaded part. For a structural bond, use Sikaflex 552 AT on a roof window and Sikaflex 265 on a side window.
What is Sikaflex 522 used for?
Sikaflex 522 is the versatile sealant for everyday joints on a converted vehicle: vent surrounds, cable and pipe glands through the bodywork, bolt-on accessories and exterior joints exposed to the weather. It stays flexible, tolerates movement between different materials and resists UV and weather.
That flexibility matters on a van, because the bodywork flexes, vibrates and goes through big temperature swings. It comes in white, grey or black, so you can match the bodywork. It is a sealant, not a window adhesive: do not use it to bond a window.
Sikaflex 522 Caravan
Flexible, UV-resistant sealant for joints. White, grey or black.
When should you use Sikaflex 552 AT for other exterior parts?
Use Sikaflex 552 AT for exterior parts that carry more load than a simple joint: brackets and body parts exposed to wind, vibration and temperature changes. It is geared towards durable adhesion on demanding mounts.
For any critical bond, check compatibility with the materials involved, work on a clean, dry, degreased and prepared surface, and respect the curing time stated by Sika.
Do you need a primer with Sikaflex?
Not on glass with Sikaflex 265, but usually yes on the surrounding bodywork. A van combines painted steel, aluminium, plastic and glass, and each substrate grips differently.
- Always clean and degrease the surface first.
- Apply Sika Aktivator 205 with a lint-free cloth where the system calls for it.
- Apply SikaPrimer 507 with a brush where the substrate requires it.
- Respect the flash-off and curing times in Sika's instructions.
For a window, a complete kit of Sikaflex 265, Aktivator 205 and Primer 507 is safer than improvising. SikaPrimer 507 is also sold separately in 10 ml and 30 ml bottles.
Which Sikaflex to reseal a caravan or motorhome window?
When you replace a caravan or motorhome window, use the same system as on a van: Sikaflex 265 with Aktivator 205 and Primer 507. First remove every trace of old sealant, then clean and degrease the bodywork before preparing it.
Changing the window at the same time? EuroVan windows, except the VanCurve, fit flat walls from 25 to 75 mm thick. Choose the same cut-out size as the old one: see our caravan and motorhome windows.
Which colour: black, white or grey?
Pick the colour for how visible the joint will be. Sikaflex 265 comes in black, which suits window frames and dark surrounds. Sikaflex 552 AT comes in white or black, to match a white roof or a dark skylight frame. Sikaflex 522 comes in white, grey or black for joints on the bodywork. SikaLastomer 831E is grey and sits hidden under the skylight frame.
Always choose the right product first, then the colour.
How many cartridges do you need?
Allow one tube of Sikaflex 265 per window. For skylights and other accessories, it depends on the size of the part and the width of the bead.
Fitting several windows? Sikaflex 265 and 552 AT are also sold by the dozen. It is better to keep a spare cartridge than to run out halfway round a continuous joint.
Which mistakes should you avoid?
- Using a sealant for a structural bond: Sikaflex 522 keeps water out, but a window needs Sikaflex 265.
- Skipping the preparation: dust, grease, old sealant, silicone or moisture cause most bonding failures.
- A bead that is too thin or broken: it leaves gaps; lay one continuous bead.
- Loading or washing too soon: avoid washing, heavy rain and strong stresses before the curing time stated by Sika.
- Confusing removable and permanent: butyl tape such as 831E can come off; a 265 or 552 AT bond is far more committing.
Not sure which product suits your job? Our technical team answers within 24 hours: contact us.
Not sure which size fits your panel?
Send us a photo of your van or caravan wall with its measurements. Our France-based technical team answers within 24 hours.
Ask our technical teamFrequently asked questions
Which Sikaflex is best for campervan windows?
Sikaflex 265, with Sika Aktivator 205 and Primer 507 to prepare the bodywork. Our Sikaflex Window Kit contains all three, enough for one window.
Can I use Sikaflex 522 to fit a window?
No. Sikaflex 522 is a sealant for joints, vents and cable glands. A window needs a glazing adhesive such as Sikaflex 265.
Which Sikaflex do I need for a skylight or roof window?
Sikaflex 552 AT. On a corrugated roof, add SikaLastomer 831E butyl tape to fill the ridges; both are in our Skylights Pack.
Does Sikaflex 265 need a primer?
Not on glass: it bonds directly to glass without primer. On metal, plastic and painted surfaces, prepare them with Sika Aktivator 205 and Primer 507.
How much Sikaflex do I need for one window?
One 300 ml tube of Sikaflex 265 per window. Keep a spare if you are fitting several windows.
Fitting a window? Get the complete Sika kit, then choose your window.
Shop the Sikaflex Window Kit
