The Build · The Van

Van Build – Vent Fan

The Executive Summary

Before insulating the roof, there were still a few things that needed to be taken care of. Installation of the vent fan was one of them. I purchased a Maxxair 4500k vent fan; a step up from Maxxair’s base model because I liked the idea of having a rain sensor that would close the lid if it began raining. I called a friend over for emotional support and proceded to cut a huge hole in the roof of my beautiful new van. The installation ended up being a breeze and now I had a fancy new fan to help create a nice breeze inside Boyd.

The Details

The walls were done, the floor was done, but the ceiling was still bare and the doors had been left untouched. It was summer and so getting the doors insulated wasn’t yet a priority and so I shifted my focus to the roof.

I knew I’d need some ventilation and so, after some internet research, I ended up purchasing the Maxxair 4500K vent fan. This is a common brand of vent fan for RVs and I’d seen many other van conversions using Maxxair fans as well. I went with the 4500 over the lower end model because of the included rain sensor. This meant that I could leave the vent open even when I wasn’t near Boyd without having to worry about changing weather. While the 4500 came with a slightly higher price tag, the piece of mind seemed worth the additional cost.

Before installing the fan, I first had to locate a flat surface on the roof that was large enough to accommodate the fan. There are ribs that create an arch over the walls and provide support for the roof of the van. There are also various grooves in the roof itself that I had to work around. I believe these grooves provide additional structure to the roof of the van and keep it from rattling in the wind.

I wanted to avoid having the edge of the van land on an uneven surface as this might be difficult to seal and could lead to leaks. I finally settled on a spot near the rear of the vehicle, just above where I thought my bed was going to be. I had originally wanted to move the fan closer to the front near where I had planned to build the kitchen, but over the bed didn’t seem like a bad idea either. It might be nice to have it act as a ceiling fan on a warm summer night.


Out of the box, the fan comes with a plastic trim piece. I traced the trim piece onto a piece of cardboard that I could then use as a template. I then traced the template on the inside of the van ceiling. I could have also done this from the outside, but it’s difficult to tell where the support ribs are located. However, it was going to be much more difficult to cut out the ceiling from the inside of the van. So with the template drawn on the ceiling, I drilled a single hole at each corner. I then took my cardboard template to the roof and lined it up with the holes. This allowed me to trace the template onto the top of the roof while being certain that I wasn’t accidentally tracing over a support rib on the inside. I then used a borrowed jig-saw to cut out the square that would fit my new fan. This wasn’t a two-man job but I called a friend over anyways. I was about to put a huge hole in the roof of my beautiful van and future home to be and I needed someone around for moral support. My cuts weren’t perfect and so I had to do a little extra trimming with the jig-saw before I was finally able to slide the fan into place.

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Once the fan was fit into place, the installation becomes a breeze. Oh, and be sure to position your fan with the door opening to the rear of the van. In case you ever take off without remembering to the close your fan door, you don’t want the wind to rip off the cover. Anyways, with the fan in place, the installation is simple. The trim around the outside of the fan contains dimples where the screws are to go. So I drill pilot holes through each of the dimples. Next, remove the fan to reveal all the holes. This might be a good time to remind you that not everything you need for installation is included with your fan so be sure to gather all your materials prior to starting. One such unincluded material is putty tape. With the fan removed and the holes revealed, use your putty tape to outline the square cut in your roof, making sure that your putty tape covers all of the pilot holes you just drilled. This will create a seal to keep water out.

Position you fan back in place over the putty tape and insert your screws into the holes; you should be screwing directly through the putty tape. With all the screws in, I used some Dicor Lap sealant around the edge frame of the fan and over top screw head to prevent it from rusting. This may have been a bit overkill, but hey, I was nervous as hell about water leaks in the roof of my new home.

It still had to be wired in, but Boyd now had a fancy new vent fan to keep things cool. It was also nice to let in a little additional sunlight as well.

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