Creating a Level Surface for Roof Vent Fan Between Ribs in Van Roof

[On Belay]

This may be an obvious question but what's the best way to create a level mounting surface for a vent fan (Maxxair in my case) when mounting to a ribbed factory roof (Chevrolet Express). It looks like their is a seller on ebay that makes adapter flanges for Sprinters, Promasters, Transits, and E-Series but none for the GM vans unfortunately. Has anybody come up with a solution?

Is putting an extra layer of butyl putty tape in the recesses enough? Should I try try to build the surface up with an epoxy?

 

[luthj]

Use some plastic to make a spacer. Get as tight of a fit as reasonable. Seal the remaining gaps with roof sealant. Sikaflex, dicor etc. No problem.

The seller on ebay is probably Hein. He may be willing to work with you to make a spacer for your van. He would need accurate measurements of your vans roof/rib profile. It may be worth contacting him. http://impact3d.com/

 

[pugslyyy]

I just cut a few pieces of aluminum for mine, and bedded everything in butyl rubber. So far it works fine (no leaks). I would use aluminum / plastic / etc over wood for a spacer just because it will last longer. Butyl doesn't do a great job of filling in cavities where it is not under compression - especially with the heat that it will see on a roof it will flow and puddle eventually, IMHO.

 

[On Belay]

I just cut a few pieces of aluminum for mine, and bedded everything in butyl rubber. So far it works fine (no leaks). I would use aluminum / plastic / etc over wood for a spacer just because it will last longer. Butyl doesn't do a great job of filling in cavities where it is not under compression - especially with the heat that it will see on a roof it will flow and puddle eventually, IMHO.

Just want to confirm I'm understanding correct that you used the aluminum bar as the spacer creating a sandwich of: factory roof - butyl tape, aluminum bar - butyl tape - Maxxfan flange. Is that correct?

 

[mezmochill]

Just cut and stack butyl tape as needed. Take your time, use fresh tape and it wont leak. Tighten your screws down evenly and moderately. screw it down firmly but not too tight.

 

[brianjwilson]

I have spacers from impact3d as well, for my sprinter. Pretty damn easy to order CNCd spacers that match the roof and ribs of the van. Much better than stacking gobs of butyl tape IMO.

 

[_hein_]

This may be an obvious question but what's the best way to create a level mounting surface for a vent fan (Maxxair in my case) when mounting to a ribbed factory roof (Chevrolet Express). It looks like their is a seller on ebay that makes adapter flanges for Sprinters, Promasters, Transits, and E-Series but none for the GM vans unfortunately. Has anybody come up with a solution?

Is putting an extra layer of butyl putty tape in the recesses enough? Should I try try to build the surface up with an epoxy?

Kim mentioned that you called. We make adapters for other vans and would be happy to add the Express to our list of supported vehicles. Can you post or send a photo of where you would like to place the vent? Then we can take it from there and let you know when we have an adapter ready for you to try. Thank you for the opportunity to help.

All the best,
Hein
DIYvan.com

 

[ripperj]

That’s an impressive vendor response... nice


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[dleeallen]

Seriously. I had been considering asking Hein but am not at that point in my build yet. Seems like a slick mounting solution. I will buy one just to have in stock for when I do get to that point. I'm still working on installing the insulation I got from Hein.


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[Petrolburner]

Plenty of fans installed with butyl tape stacked up. Will you be able to see it when you're done? Roof top lounge chairs?

 

[ripperj]

Lots are installed that way, it’s not a looks thing, the butyl keeps oozing out as you tighten the screws over a period of time( not supposed to be a one time tighten and walk away) and eventually the fan or vent or window is up tight against the ribs on some sides and not others, then things start to distort

Does it matter? Will it leak? Don’t know , but a proper seating surface will greatly increase the odds it won’t. ( that and properly applied eternalbond tape around the whole flange)


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[Petrolburner]

I didn't know I needed to tighten the screws for my fan overtime. I'll have to check on them.

 

[On Belay]

I was able to take some photos. I'll send them to Hein as well, I didn't realize that was his eBay store.

I think the GM vans have less pronounced ridges than some other models. It's really only about a quarter of an inch recess.

I've actually already cut the hole (I was painting the entire van) so turn around time is kind of a limiting factor. The aluminum/plastic space in the groove with Butyl Tape and Lap Sealent may be a passable solution.

 

[ripperj]

Petrolburner- seems like the best way is to snug up the screws during the initial install and then again a few days later and then maybe one more time a week or so later, I’m only talking part of a turn on each screw. I’m certainly not claiming to be an expert, but I did a lot of research and it worked for me so far( I have rolls and rolls of butyl on my Alaskan I rebuilt)


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[_hein_]

Petrolburner- seems like the best way is to snug up the screws during the initial install and then again a few days later and then maybe one more time a week or so later, I'm only talking part of a turn on each screw. I'm certainly not claiming to be an expert, but I did a lot of research and it worked for me so far( I have rolls and rolls of butyl on my Alaskan I rebuilt)

The gap and roof curvature isn't too large that butyl tape would not work. Just use two or three layers in those areas with more gap. Looks like there is a roof coating that you might want to prep first. We can make an adapter but wouldn't have that ready for you until sometime later next week. We will go ahead with adding the product for future customers. We've produced these for placing vents on curved fiberglass caps as well.

What year is your van?

All the best,
Hein