Installing roof rails is a crucial step in our VW Crafter camper conversion.
Not only do they form the base for our future solar panels, but they also need to be strong, watertight, and lightweight, especially when doing a DIY build like this one.
If you’re wondering how to install roof rails to your campervan, we’re going to show you how we installed aluminium roof rails on our 2019 VW Crafter using 40x40mm aluminium extrusion profiles, without drilling into the roof.
Products Used in This Install
Why We Chose Aluminium Over Steel Unistrut
Weight matters in a van build. I wanted to avoid putting unnecessary load on the roof, so I opted for aluminium extrusion instead of the commonly used steel Unistrut.
The 40x40mm aluminium profile is much lighter and still incredibly strong.
I split the rails into four 1-meter sections: two on each side with a gap in between.
This not only reduced weight but better accounted for the natural slope of the Crafter roof, avoiding stress points that could cause leaks later.
Quick Summary: How to Install Roof Rails on a VW Crafter
- Locate factory roof bolt holes under plastic caps
- Clean and paint exposed holes
- Apply butyl tape and Sikaflex to seal bolt holes
- Insert stainless bolts through aluminium rails into roof
- Tighten with washers and Nylocks from inside the van
- Use Loctite for anti-vibration and long-term hold
- Install early to use as a support deck for future roof work
Finding the Mounting Points on the VW Crafter Roof
If you’re working on a VW Crafter (ours is a 2019 model), you’ll notice small plastic caps in the roof gutters.
These are pre-drilled holes from the factory for roof rack installation: perfect for a camper conversion.
I used a heat gun to soften the adhesive, then gently pried the caps off with a screwdriver. If you’re worried about scratches, use a plastic scraper.
I wasn’t too concerned here since I planned to paint the exposed holes anyway.
After cleaning the area with a degreaser, I hit each exposed hole with a quick coat of paint to prevent rust and neaten them up.
Waterproofing the Roof Bolt Holes (Butyl Tape + Sikaflex)
Once everything was cleaned and painted, it was time to seal things up.
I used mastic sealing strips (butyl tape) and marked the bolt positions with scissors.
To seal the connection from the top side, I placed a strip of butyl over each bolt hole before pushing the bolts through.
Then I applied Sikaflex 522 around each bolt. It’s a belt and braces approach, this combo ensures the bolts are properly sealed and won’t let water in over time.
Tip: This waterproofing step is essential if you’re doing a DIY campervan roof rack install. Leaks in the roof are a nightmare down the road.
Choosing the Right Bolts for Aluminium + Van Roof Connection
I used A4-grade stainless steel bolts – the same kind used in marine environments – because they don’t corrode and are compatible with aluminium.
For each 1-meter rail section, I used four bolts:
- Two slide-in T-bolts (must go in from the end of the profile)
- Two hammer bolts (can be inserted anywhere)
This combo gave each section maximum grip inside the aluminium channel.
From inside the van, I added a washer, a square of mastic tape, and a blob of Sikaflex, then tightened it down with a nylock nut and a grover anti-vibration washer.
I also added a tiny drop of Loctite 271 (red) to keep everything locked tight. I learned that trick from my tractor mechanic days, this way the bolts won’t back out, even after thousands of miles.
Want to know the best bolts for aluminium and van roof connections? Use M8 A4 stainless bolts with nylocks + threadlocker for long-term durability and leak protection.
Solo Roof Rail Installation: Yes, You Can Do It Alone
Even without a second person, this was completely doable.
I slid the aluminium rails onto the bolts from the outside and pressed them down onto the butyl tape. Inside the van, I added washers and nuts and tightened them up.
The profile held the bolts in place, making it easy to secure everything without needing an extra set of hands.
Looking for tips for installing roof rails solo? Use bolts that lock into place (like T-bolts and hammer bolts) so you can tighten them without needing someone to hold them from above, it makes solo installs way easier.
Why Install Roof Rails Early in a Camper Build?
We’re not adding solar panels just yet, but I wanted these rails installed now. Why?
I’ll be using them to temporarily support a plywood plank while I fit the Maxx Air Fans. The plank spreads my weight across the rails instead of denting the van’s thin metal roof.
Extra Tips for Better Roof Rail Setup
- Order rails with only 2 grooves instead of 4 to reduce wind noise.
- Add plastic end caps for a cleaner finish.
- Never overtighten, aluminium threads can strip. Stick to the bolt torque specs.
- Always use fasteners designed for vehicles. It’s tempting to cut corners here, but trust me, you’ll regret it on the motorway.
Final Thoughts on Our Crafter Van Roof Rail Installation
If you’re working on your Crafter van conversion and thinking about roof racks or solar panels, installing roof rails now is a smart move. Doing it with aluminium rails keeps things lightweight, corrosion-free, and safe, even for solo builders.
Whether you’re installing roof rails for solar panel prep or just need a strong foundation for roof mods, this method is beginner-friendly and field-tested.
Let me know if you’re planning your own DIY campervan roof rack setup, or if you’ve got questions about anything from sealing techniques to bolt choices.
Next up: installing the Maxx Air Fans (and yes, we’re cutting into the roof — stay tuned).
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