stabilize roof for fan?

[MAJORJDB]

I am installing a fantastic vent fan Model 7350, replacing the OE vent/light combo in my 1989 Excella... It was fairly straightforward, squared up the rounded entry hole into the coach. I am looking for guidance because it seems like the roof panel flexes a lot and the roof curvature causes a gap between the fan base and roof. I can push it down to eliminate the gap, but I am afraid it might cause a water pooling issue. Should I make a curved support and fill the gap with sealer or screw the fan to the roof allowing the flex to close the gaps... Any advice would be appreciated...

[Lumatic]

Originally Posted by MAJORJDB

Should I make a curved support and fill the gap with sealer or screw the fan to the roof allowing the flex to close the gaps... Any advice would be appreciated...

I have installed 2 Maxx Fans and one Fantastic fan and did not install a support. No Problems,

[uncle_bob]

Hi

One consideration: What happens when you forget to lower the fan and run on down the road? With the "normal" factory install ... not much. Yes indeed, I have data on this

Bob

[MAJORJDB]

Bob,
I definitely hear what you are saying, any recommendations for added stability would be helpful...
Jim

[A W Warn]

There was no reinforcing on three sides between skins at the either of the Fantastic fans in my Safari when I purchased it. The roof skin at the front fan had a stress crack at one corner, I assumed was from movement. I added wood reinforcing to both of those fans.

I used aluminum to reinforce the roof when I installed the Fantastic fan in my Excella this past winter, and also when I installed a new AC unit a couple years ago.

Wood is easier IMO to make it fit the curve. If you do use wood, do not use treated wood since it can corrode the aluminum.

[HiJoeSilver]

Apply extra layer of butyl tape/putty around the outer(away from centerline) edges to tighten the fan down into then seal around that with some self leveling dicor lap sealant.

[CRH]

I used high density foam between the inner skin and roof. I cut a piece, compressed it and put it in. It was enough to push the low spot in front of my fan upward.

[MAJORJDB]

All,
Thanks for the input, will add wood support and foam to fill any small gaps. Last year I upgraded the A/C with a low profile, larger output (15k vs. 13.5) w/a heatpump and weighing half as much (it seemed) with no problem, fit like a glove and no added support. It appears that the OE fan has its own support in its metal framework....

[A W Warn]

Originally Posted by CRH

I used high density foam between the inner skin and roof. I cut a piece, compressed it and put it in. It was enough to push the low spot in front of my fan upward.

That's a good idea! Foam could be shaped to the curve as needed with a rasp.

[CRH]

The foam I used wasn't hard styrofoam, although your idea would work great. What I used was high density foam like in a cushion. I compressed it and pushed it in the gap. It sprung back and lifted that area of the roof just enough to direct water away from the front of the fan.

[Al and Missy]

I framed the opening with 1/8"x 1" Al angle from Lowes. The gaskets that come with the fan ultimately take a set and leak. Using sealant is better, but the flex of the roof can crack the joint and cause leaks (don't ask how I know). Adding the angle gives a nice strong flat backing plate for the skin to ensure a lasting sealant joint.

My front fan was very close to my TV antenna. The whole roof in that area oil-canned. I squirted spray foam in there all around the fan and antenna. Turned that area of the roof into a foam-core sandwich panel. Strong enough to walk on now (although I don't).

Al

[flyerboy]

In our 2008 Classic, I took a straight edge across the top of the crown and measured the gap from the straight edge to the roof on each side about 3" wider than the opening on each side and replicated the arc of the roof onto the side of a 2X4 and cut it out with a jigsaw basically as thick as the gap between the inner ceiling panel and the outer roof panel. I then placed two of these, one in front and one to the rear of the opening and screwed my MaxxAir fan flange with stainless steel screws through the roof and into each one of these arches. I also ran two other "sticks" longitudally front to back between the two arches to screw the sides of the fan into as well. Basically made a frame of wood in between the inner and outer panels.
Took some time and patience, but...
NO BEERCANNING!
EVER!