Van Build Diary 5.3: Roof Rails, Oh Roof Rails, What for Art Though Roof Rails?

Updated: Feb 16, 2021

This post goes into the difference between roof rails and a roof rack, why you absolutely should have them, and how to install them (and try to not have to). It is part of a roof-top series that includes:


5.0 – Figuring out what needs to go where on the roof and timing

5.1 – Ventilation – why 2 vents, why Maxxair, how they were installed

5.2 – 12v Air-Conditioning – a confusing and stressful topic, what we went with, why and how

5.3 – Roof Rails – why you should ALWAYS install them and how to install them (the one you’re reading now!)

5.4 – Bed Liner - why, where, and how


Without further ado, here's the post and a quick disclaimer that there are some affiliate links- I may receive a small commission (at no cost to you) if you purchase through the links provided. (Learn more here) Thanks for supporting On An Imperfect Journey!


Roof Rails vs. Roof Rack


Albeit a quick one, this post is an important one for all the beginner DIYers out there. First of all, some beginners might not actually know the difference between roof rails and roof rack.


Well, that’s a simple one: the roof rack is the thing we all might appreciate and use up on the roof to store additional items. We can attach those Thule boxes on top, or strap things down to it with bungie cords (suitcases, duffle bags, surfboards).

a vintage car with a wooden rustic roof rack installed on top in a snowy area
Rack only - I think it's fantastic!

A blue vintage minivan with a roof rack and a canoe and storage box attached. Parked in from of some snowy hills
A Rack with all sorts of stuff attached to it!

Roof rails, on the other hand, are the very thing that roof racks attach to, other items for that matter (roof-top bike-rack, roof-top deck, solar panels, etc.) Roof rails are things that MUST BE ON YOUR ROOF before you can attach additional “stuff” up there because everything else you want to attach up there can only hold if those things are attached to the roof rails.

the roof of the van with the two roof rails installed. You can also see the two vents and air conditioning installed too.
There they are! Now anything we want we can attach!

For those of you who might have bought your car with a bike rack or a Thule storage box or a roof rack already installed, then you can take a quick look at your car and see the rails running down both sides of the roof, from front to back that those other things attach to. Yes, that is a totally separate thing – roof rails!


Why You Should ABSOLUTELY Install Roof Rails


Even if you are not planning on having anything attached to your roof right now – I get it, there’s a lot to already consider and a lot already to figure out, AND . . .


GET THOSE ROOF RAILS ATTACHED NO MATTER WHAT!


Why, you might ask, am I screaming this through the page?


Because you don’t want to have to realize later on that you wanted more storage on top, OR that it might be the coolest thing ever to have a roof-top deck to sleep under the stars or star-gaze or enjoy better horizon views of the sunset, OR that solar is a really helpful way to recharge your batteries in a clean way, or that you want to have a roof-top bike rack to keep an unobstructed view from your back windows or whatever other reason you might find down the road.


Why is it a headache later on? Because you have to take apart your ceiling! The screws that attach it to the roof have accompanying nuts that have to mount in on the underside of the roof and your ceiling will be in the way!

The inside of the Sprinter roof with the screw from the roof rails sticking through.
That is going to get covered by your ceiling!
a zoomed out view of the inside of the van roof, with arrows pointing to the place where the screws are screwed in on the inside
A better idea of where they are

It is an easy, relatively inexpensive installation (and, as I explain below, you can get them factory-installed if purchasing from the factory is an option). It will save you the headache later.


So, just do it now!!!


Pre-installed or DIY-installation?


Here’s the thing. . . most of you will likely go for a shorter van – a 144” wheelbase or a 170” wheelbase that isn’t extended. In your case, you can go the cheaper route of getting after-market roof rails that are cheaper and VERY easy to install.


If, like us, you have a 170” wheelbase extended, and you’re buying it new, just get it added on to your factory-install. In the alternative, you can order it from Mercedes Benz but read on to make sure the right # of nuts are ordered. OR, you can order from an aftermarket supplier but do not give your payment until you’ve been put on hold and someone has gone down to the warehouse floor and made sure that the accompanying hardware is IN the BOX!


Again, I think you’ll find the factory install to be less of a hassle when you listen to our story:


I’m not used to buying new cars so it didn’t occur to me to reach out to the MB parts department. I guess it was a good thing, on one hand, because we probably saved a couple hundred dollars ordering the rails from an aftermarket shop.


Now, I won’t name the shop, because s#*t happens everywhere and I think this could honestly happen anywhere. But IMPORTANT INFO gathered: This shop, as is the case with many, only carries one set of roof rails for the 170 extended. It had been sitting in the warehouse for forever and, as can happen, in being shoved around a bit. . . the hardware fell out. . .


So, our lovely rails arrived with no hardware!!!


Two weeks and several phone calls later and the shop still hadn’t gotten ahold of MB to get the hardware. That’s when it occurred to me, oh, I should contact Mercedes Benz myself!


A 90 min. conversation later, they had more or less figured out what I needed but I needed to go to the location to put in the order, which is no easy task fitting into our schedules. An hour-long visit to the dealership and I find out the rails cost more. So, I order the hardware only.


Guess what? The parts department can’t figure out how many nuts I need. Now, the screws come fixed to the rails and any old stainless steel (rust-prevention) washers can work. The important piece is the nuts. . . So, they print out the installation document they have and we count up the # of nuts in the picture and that’s what we order!


Another week later, and the nuts have arrived. Ready and excited to install that upcoming weekend! Except. . . there aren’t enough nuts!!!!! The document that accompanied the part # at the dealership (mind you, they looked up our VIN # so they knew it was extended) showed the installation of the regular 170 rails, which is why there weren’t enough nuts!!!


Two phone calls later, a failed attempt to put an order in, and now Mercedes Benz is feeling embarrassed at how they dropped the ball on my order and they order the additional nuts at a discounted price (eventually they refunded me)!


And so, two months later, WE FINALLY INSTALLED THE 2ND RAIL!!!!


I’m not saying this will happen to everyone but it was a headache. At the same time, I also get that not everyone can afford to pay the higher MB prices. Just remember that, as of the time of writing this, there are no aftermarket rails only aftermarket shops that probably get the rails at discount and so, can offer it cheaper.


So, if getting pre-installed isn’t an option, try the aftermarket route but (as I mentioned before), MAKE SURE the shop hasn’t lost the hardware (which, if it’s been sitting around a while, is a good chance).


Installation


Roof rails are probably the easiest thing to install. If you get the MB rails, the rubber gasket (what keeps the rail from rubbing up directly against your roof) is already installed. The screws also come screwed into the threaded holes.


The only thing you need to do is:


1) With a heat gun, heat the glue that’s holding the current plugs in place. When the glue is hot enough, you can peel it off with a rubber or silicone scraper (so you don’t scratch the metal). Repeat until all are removed.


Ok, embarrassing moment. . . A hair dryer will not suffice. Maybe you can now fully comprehend how foreign this all is to me. In all the youtube videos I watched, I actually thought they were hair dryers!

a heat gun
NOT a hair dryer

So, you actually need a heat gun, which gives A LOT more heat than a hair dryer is capable of, haha. And you need one anyway if you plan on crimping your own electrical wires.

the hole where the plastic plug has just been removed with a heat gun
All off!

2) Add little squares of butyl tape over the holes. This adds a waterproof seal (Some aftermarket rails don’t come with the gasket already on the rails. You can just line the whole rail with butyl tape and it will act as both a gasket and a seal).

3) Set in the rails with the screws in the now opened holes, puncturing the butyl tape where the screw enters.

4) From the inside of the van, place the washer and then screw the nuts in tightly. YOU NEED 24 (GRAB A COUPLE EXTRA JUST IN CASE FOR A TOTAL OF 26)


And voilá! You have your rails installed.



All that waiting, calling, ordering, and more waiting, and the install was done in a few hours!


If you want to see a really helpful install of some aftermarket rails on a 170, Kevin from Mathers on the Map takes you through the whole process. . . I highly recommend it!


So, now we’re ready for roof liner! Which you’ll learn about in the last post of the series!


And hopefully, the next series can be about our electrical system, or the attic box (which has to go one before our solar so. . . until next time! And subscribe above if you want to be alerted as to new posts coming out!