Maxxair Fan Install Question

[jayhawksw]

I've noticed some people use Butyl tape plus silicone sealant and others use sealant only. Any advantages or disadvantages in the two? Also what silicone sealant do you recommend? Thanks in advance

 

[Canine]

I hate silicone. I used what the manufacturer recommended: Butyl tape then Dicor lap sealant. Get the non-sag formula if the fan is being mounted on a vertical surface.

 

[John61CT]

Butyl yes.

Outer sealant, 3M 4200, Sikaflex 291, Rectorseal 81880.

Anything but sillycone, avoid like the plague.

 

[jayhawksw]

Okay, no silicone, but why? What is the problem with it?

 

[Canine]

All sealants fail at some point due to age or mechanical damage; nothing lasts forever. When that happens and it comes time for maintenance or repair, silicone is an absolute bear to clean off. The surface has to be free of silicone before anything will stick to it. It doesn't even like to stick to itself!

 

[QinReno]

This is not my area, but this guy jamie who favors himself a guru on van builds, has a new video on this exact thing. Uses both butyl tape and dicor sealant. He runs the van build in AZ in november. (FYI only).

Bob Wells also has videos on fan installation.

Dicor is apparently EPDM, which is a synthetic rubber.
https://www.google.com/search?q=epdm

 

[deadwood]

I used 3m VHB tape to secure my maxair fan to the roof. I then also used some 3m 4200 to seal it from the inside as well as the outside. And then a nice layer of Dicor on top to keep any water out. 45k miles later and it isn't going anywhere. I was happy to not have to drill any holes into the roof. At least anymore holes then I already made.

 

[MrNoodly]

When I was installing my fan five years ago. someone here recommended 3M Window Weld -- the stuff they use to glue windows to vehicles. Everyone else recommended butyl tape and Dicor. So I went with all three. I layered the tape to compensate for the ridges in the roof. Then I applied a bead of Window Weld about as thick as my thumb to the bottom of the fan flange. It oozed out all over, but I wiped it up and made sure there were no obvious gaps. Then I coated the outside of the flange and the screws with Dicor, which I recoat every couple of years. I've had no leaks.

 

[jayhawksw]

I'm hoping someone can help me out here- I'm on my way now to Fiberine for my appt. on Wed. and I'm not finding any of the exact products recommended at Lowes or Home Depot. Lowes had Camper Seal foam tape but not Butyl. Is it the same stuff? They didn't have any of the sealants you all recommended either. I'm looking at Home Depot's website and they show 3M 5200 but not 4200. Amazon doesn't have anything called Sikaflex 291 either. All the Sikaflex stuff Home Depot does have says it's for concrete. Is that right?
Help, I'm not sure what to get and need it by Wed.

 

[Almost There]

Butyl tape will be available from either an RV supply store or a marine supply store.

I recommend trying to get it from the marine supply store if at all possible.

The beige butyl tape is marine grade and has a life expectancy twice as long as the gray butyl tape that most rv places use.

I'm surprised that Fiberine doesn't have it on  hand, they'd use it for installing windows in the side of the fiberglass tops!

 

[John61CT]

This is the best, see if MaineSail can FedEx

https://shop.marinehowto.com/products/bed-it-tape

Or try https://shop.hamiltonmarine.com/products/butyl-tape-bed-it-1-2--x-50--roll-4482.html

 

[Reducto]

Butyl tape by itself is enough in the short term. That's all I used on my first van install and it was fine for years. I think people see the dicor as extra insurance.

You should be able to find it locally at an rv shop and possibly walmart.

 

[jayhawksw]

Any suggestions on which sealant to go with that Lowes or Home Depot carries or another place to get the stuff you all recommended?

Fiberine said they would use silicone sealant to do the fans, which is why I originally asked the question here. I had asked Fiberine if they used Butyl tape and sealant. They said they do not but that I was welcome to bring anything I wanted them to use instead.

 

[John61CT]

I'd rather do it right (good quality butyl tape)

even if it means delay. Get them to cut & drill but not seal the fan?

Do not allow any silicone-based sealant, means nothing else will ever stick there.

Check out marine places? Sika 291 or 3M 4200 are fine, but 5200 is a very permanent adhesive.

Not sure about UV protection, that can be an issue.

Check out this thread http://www.cruisersforum.com/forums/f55/3m-5200-imho-22652-2.html#post242468

 

[jayhawksw]

Okay, I found a Home Depot in LA that has the 3M 5200. With it being "very permanent" it is a little concerning though should the fan ever stop working and I need to replace it. Still looking for the Butyl tape. The marine stores I've called so far haven't carried it. I'll keep looking.

 

[jayhawksw]

Hurray! Props to Mike Thompson's RV Super Center in Colton, CA for carrying both the beige butyl tape and the Dicor lap sealant. You all have no idea how many phone calls I had to make to find this stuff. Crazy. Thanks for the help.

 

[John61CT]

Okay, I found a Home Depot in LA that has the 3M 5200. With it being "very permanent" it is a little concerning though should the fan ever stop working and I need to replace it. Still looking for the Butyl tape. The marine stores I've called so far haven't carried it. I'll keep looking.

Yes 5200 will need serious chiseling to remove, likely damage the surrounding roof, do not use that.

Just butyl by itself will do for quite a while, even forever if you don't mind how it looks.

Ever get a leak, super easy to re-bed.

 

[becida]

I hate silicone. I used what the manufacturer recommended: Butyl tape then Dicor lap sealant. Get the non-sag formula if the fan is being mounted on a vertical surface.

What Canine said.... Butyl tape under the flange, clean the excess then Dicor around the edge & on every screw head.