Adding a vent to roof

I did it. The 14" hole snugged in perfectly between the 16" OC roof trusses. As others mentioned, I also added 2x4 bracing around the new hole. It worked out great. Just take your time to find the right place. I pulled down light fixtures so I could peak around up there, then tapped into one of the fixtures to power the new fan. Seriously excellent mod!

I did this on my cargo trailer/camper.

The roof top should be enough to hold a vent up there with no additional framing or support, but go ahead and insert some wood frame in the cavity between the roof and the ceiling, as mentioned, to screw to. This will allow the vent top and bottom to sandwich and pull the ceiling and roof together tightly. Just pieces of wood are good enough, it doesnt have to even connect at the 4 corners like a picture frame would, they will just be taking up space and making the distance between roof and ceiling rigid. For making it waterproof you will want some rigid structure so the roof cannot flex and cause a leak.

My cargo trailer came from the builder with one vent, and they attached wood framing so the interior assembly would fit right, but it was just hanging from the roof sheeting, not attached to any real structure. Chincy, yes, but it has held up fine. I have since put an interior ceiling and insulated it better, so it like a camper.

I added an AC to the roof and did it correctly with welding and new steel tubing to frame in the opening and also connect to the other roof frame members, but this is overkill for just a vent, unless you might put an AC there one day...

have fun

I'd skip the one in the bedroom and concentrate on the Living area vent. We open windows in the bedroom and the Living Room exhaust pulls in the fresh air.
I would add an exhaust fan in the living room vent which, of course, makes the project even more difficult.

I just did this to a 2016 Coachmen Apex 239RBS. I had the same issue of not enough ventilation in the front (bed area) of the camper. I do have a fan (small, one speed) at the rear of the camper in the bathroom and thought about just replacing that with the Fantastik fan, but I just knew it would not work as well as having the fan up front.

My roof is nothing more than a sandwich of rubber over 1/4" luan plywood, 4" to 5" of styrofoam and the ceiling which is 1/4" luan. I used a magnet to locate supports (mine are steel) and they are 4' on center.

I have ceiling lights that run in the center and length of the camper that I was able to get power from. The wiring actually lays on the ceiling in a hollowed out "raceway" in the styrofoam.

They sell a vent install kit which will have butyl tape to use under the vent lip, mounting screws and dicor caulk to seal the top.

So far so good. No leaks and nice air movement up front.

The X cut on the rubber is an excellent idea! Also I would also put blocking around opening. The way these things shift and twist going down the road I think you would have problems eventually.

I would put down a solid bead of Dicor under the flange before tightening it down and then use Eternabond around the edges. Finish with small bead of Dicor self leveling around edges of Eternabond. Just do a periodic check on Dicor and reapply when needed.

Good Luck and happy camping!

Dave

If you were to cut the hole and find a sandwich of luan, I would put some blocking around the edges of the hole so that you had something to screw the vent into.

The only other concern would be ducting. When you cut the roof membrane, cut it corner to corner (X), leaving as mush roof sagging over the edge as possible.