Note: This post contains affiliate links
Our day was going something like this:
“Okay, here we go.”
“Wait, did you double check the measurement?”
“Yeah, I did, but maybe I should do it again.”
“It’s probably fine, but you should check one more time.”
“Okay, then you should recheck my marks.”
“Great, then you can check mine.”
This went on for at least a half an hour until we were confident enough to start firing up the power tools. Thankfully, the in-laws were in town and handled the post-nap time beautifully; leaving us time to finish the job.
Cutting a big hole in the roof of your new van to install a vent fan can be intimidating. After all, you are forever changing the integrity of your vehicle’s envelope. Do it wrong and you will be plagued by drips, slippery floors, grumpy family members, wood rot and rust. Do it right, however, and you can enjoy a fresh breeze blowing through the interior on a hot day, or eject the smell of the burnt pasta dinner you made on that rainy night in Squamish.
You will need:
Vent Fan (We love the line of Fan-tastic Fans and have used them on both the $1500 RV and the new Home On The Loose)
3/8” metal drill bit (or whatever width your jigsaw blade is)
Metal jigsaw blade with the most TPI you can find (24 TPI is okay, 36 is better!)
Pliers (we like linesman pliers for this job)
A large towel
A large plastic bag
Design: First, you will need to decide where on your roof you will place your fan. Things to consider are:
Where you will be drawing air in. (e.g. vented windows in the front or back or rolled down front windows) You want to have a nice long way for the air to travel if you want to create a breeze inside your van.
Where you might be creating smells that you want to exhaust quickly. Think burnt pasta dinners, or the location of your porta-potti if you decide to have one of those in your van.
The location of other roof elements. Before cutting, we recommend test fitting other items. Our roof only has two 100 watt solar panels and the fan, but you may have other gear (racks, antennae, SUP/kayak, bikes, epic sunset watching platform, etc.) that you would like to have up there which would affect the placement of your fan.
In our original design, we had the kitchen pushed up front behind the kids’ seats. We planned to have the vent fan right above where we might cook and a set of vented windows on the back doors that drew air across the whole sleeping platform. Alas, the design changed with the new bench conversion bed and we have not prioritized putting in the back windows. As it stands now we have a crummy short airflow. This is still very helpful when the kids are sleeping in the van during driving days but it gets rather hot in the back unless we crack the rear doors.
Once you have your roof design down, you will want to mark out the location of your vent fan hole. We went with the standard center of the roof install, you may want to shift to one side or another but beware that the Sprinter has very few straight lines and the closer you get to the edge of the roof, the more you will have to take this into account.
We found the center of the roof by measuring in from each side. As it turns out, there is a handy reference point as the center of the roof has a rib running down it! We used the specs from our Fantastic Fan installation guide to let us know how big of a square we would need. (ours was 14”x14” but read your manual before marking and cutting!)
Marking with a pencil we then measured out from our center point to get the mid points of each line. From the midpoints we extended to the corners to get our square. We obsessed for ages about why our diagonals were not coming out correct and through our original midpoint. Eventually, we came to grips with the fact that the uneven plane of the van roof was not going to allow for a perfect geometric plan and we put our perfectionism aside. We used our square to ensure that each corner was 90 degrees and that each side was 14”. We measured many times and eventually marked in our final cut lines in Sharpie.
Chuck a nice large metal drill bit into your drill. You will need a hole that is big enough to fit your jigsaw blade through when you cut your lines. Take a deep breath. Maybe check your lines one more time. This is a good time for a little extra fuss and worry.
Pop on your safety glasses and hearing protection. Center
your drill bit so that your hole will be just inside the corner of your marking lines. One more deep breath, then commit. Drill holes in each corner of your marked square.
Head on up your ladder to the roof. I like to throw an old bath towel up on the roof whenever I am working to help prevent scratches from anything that’s sticking to my shoes. Using my square and straightedge, I marked out my cut lines on the roof by connecting the dots.
Using the duct tape, affix a large plastic bag on the underside of where you will be cutting. The jigsaw will create a ton of small metal shards while you cut. Since we had already installed the finished floor and kids’ seats we didn’t want to be vacuuming up for days. The idea was to catch most of these in the bag for easier disposal. It worked!
Before cutting, pad the roof with painter’s tape. Also, cover the jigsaw’s foot with painter’s tape as well. This will help prevent scratching up the van roof while you cut. I had to stop a few times to reapply tape as needed. With your high TPI (teeth per inch) metal jigsaw blade, cut along your marked lines. Try to make your cut as straight as possible, but don’t beat yourself up over a little freehand wiggle.
Cut along all four lines and pretty soon you will have a nice big hole in the roof of your van. Well done!! Call the family over and make sure to take lots of pictures of everyone sticking their head through the hole. Be careful though, it’s sharp!!
This is a good time to dry-fit the fan. Pop your fan into your newly made hole and ensure that it will seat itself and that you don’t need to trim up any of your cuts. Unless you have installed your fan right in the one flat spot on a Sprinter’s roof you will notice that the center rib is impeding your fan from sitting flush to the roof. Don’t Panic! There are a few ways to deal with the roof rib. You can pound the rib flat where it impedes your fan trim, cut it away or cut and bend the remaining metal.
For our build, I used a hybrid of methods to deal with the rib. On one side there is a notch cut that the fan slides under, on the other side we cut into the roof rib and then bent back the remaining tab to form a shelf. To do this, I used the jigsaw to cut the sides of the roof rib. I then bent back the side tabs this created leaving the top tab intact.
The Fantastic Fan slides nicely under this tab on one side, but we had use our linesman pliers to bend the tab on the opposite side to create a small shelf for the fan to sit on.
Once you have dry-fitted your fan placement and ensured you have a large enough hole and that the fan will lay flat, it’s time to make it permanent. I started by outlining the top side of our hole with a single layer of putty tape. The fan was then placed flat to the roof. It is very important to install the fan so that the vent opens towards the back of your van.
This will prevent the vent fan from ripping off at high speeds when you forget to close it! Last, screw your fan down, through the putty tape and the roof of the van. Don’t worry about the screw heads protruding into the van interior, layers of insulation and ceiling will cover these later.
As an additional precipitory defense we then applied a bead of polyurethane sealant to the edge of the fan’s exterior and a dab of PU sealant to each screw head. Be warned: the sealant is black, gloppy and seems to be permanent. Wear gloves when applying and a pair of shorts you don’t care being permanently stained. The finished look of the PU sealant can be a bit messy which was not a concern for us as we will rarely be up on the roof. If you would like a more finished look, you can spend more time smoothing over your sealant job.
You have done it. Step back and admire your newly-installed vent fan. I left the interior trim piece off while the interior of the van was built out and added it later when we built our ceiling. Once your electrical system is hooked up you can wire up your fan and enjoy the cool breeze wafting through your awesome Home On The Loose. Nice job!
See you out there,