[split] How do I install a vent in a Fiberglass Roof

[NW Van Man]

Hello all..new subscriber here looking for some info. Want to install a fantastic fan vent in my 93 Ford E350 van that has a fiberglass top. Has anyone done it and are there any special considerations over a metal roof. Thanks

 

[highdesertranger]

if you have a double wall roof you need furring between the layers. also do not screw into the fiberglass as an anchor, put furring under the screws and screw into that or use small bolts however even with bolts it's best to use furring. highdesertranger

 

[accrete]

:   ) everything He said .

For our build we have a 24" fiberine roof and a ~3" drop ceiling.

Here is a picture of the original Fantastic fan (now thankfully!! replaced with a MaxxFan) with the insulation sandwich before installing the headliner (seen in the photo after this one) :

Here is the finished product. We installed LED lights in headliner too.

The swap out of the Fantastic to MaxxFan was of course a breeze as all the _work_ was already done! Just unscrew a few wood screws and reapply all the goop ; )

Thom

 

[SternWake]

Fiberglass can be tapped for a machine thread if at least 3/16 of an inch thick, and the proper size drill used before the tap is run through it. I'd use one size smaller a drill bit than is used in Metal tapping, and go slow and back off the tap often and blow out the bits.

However wood furring strips on the other side with wood or sheet metal screws is easier.

Bolts nuts and large washers is another option, but requires somebody inside to hold the nut while the screwhead is turned.

Use some Butyl rope under the flanges on the exterior, and some good UV proof sealant on the screw heads. Eternabond tape is pretty good stuff too when applied correctly, but it must be considered permanent when adhered. One needs to grind off.

There is more than one way to skin this cat. My way is not the only right way.

Definitely have a method to catch any fiberglass dust inside, when cutting the hole for the Vent, and a metal cutting bit on a jigsaw will make the cleanest hole in fiberglass. One might consider sealing the edge of the fiberglass where it is cut, and some fiberglass roofs have a layer of foam sandwiched in between, and this should be sealed in belt and Suspenders fashion.

 

[66788]

I have a 1/4 inch fiberglass high top and chose to just make a 2" X 2" wooden frame instead of using the inside trim provided by the manufacturer.    Cut out opening, drill holes through roof, screw to wooden frame.   Simple.

 

[NW Van Man]

:   ) everything He said .

For our build we have a 24" fiberine roof and a ~3" drop ceiling.

Here is a picture of the original Fantastic fan (now thankfully!! replaced with a MaxxFan) with the insulation sandwich before installing the headliner (seen in the photo after this one) :

Here is the finished product. We installed LED lights in headliner too.

The swap out of the Fantastic to MaxxFan was of course a breeze as all the _work_ was already done! Just unscrew a few wood screws and reapply all the goop ; )

Thom

 

[accrete]

Insulation on ceiling ?
Well, in hindsight, the first step is make sure your partner (in my case, my dearly beloved MacGirlver) is wearing a shower cap!

3M77 Adhesive spray on the bare fiberglass and on the bubble-wrap/foil let set 1 minute, then apply.

Thom

 

[One Awesome Inch]

I have a 1/4 inch fiberglass high top and chose to just make a 2" X 2" wooden frame instead of using the inside trim provided by the manufacturer.    Cut out opening, drill holes through roof, screw to wooden frame.   Simple.

That is awesome!

 

[GypsyDogs]

My van (87, single ply fg) is so old and the shell is thin.  I am too paranoid to put a vent on the roof.. for fear the bouncing down the road will stress it from the weight of the vent.. and cause catastrophic roof failure.  Instead, I plan to add 2 top-line vents in the rear plexiglass porthole window.  

combine two of these TrailerWallVent3
with a couple of these 80mm-120mmAdapter
and a set of 'quiet' 120mm computer fans that are rated around 100cfm and 25-30dB
12v speed regulator to adjust airflow..
combine that with an air inlet at the side barn door (in the vertical part of the step- I will install a screened forced air floor register)

That was my solution to my paranoia of destroying my antique fiberglass roof shell..   LOL

 

[accrete]

IMO, nice thinking outside the van-box GypsyDogs. When you get the mod done hopefully you can share some images. ? !

Thom

 

[NW Van Man]

Insulation on ceiling ?
Well, in hindsight, the first step is make sure your partner (in my case, my dearly beloved MacGirlver) is wearing a shower cap!

3M77 Adhesive spray on the bare fiberglass and on the bubble-wrap/foil let set 1 minute, then apply.

Thom

 

[highdesertranger]

actually for overhead gluing I would bump it up to 3M90. highdesertranger

 

[accrete]

actually for overhead gluing I would bump it up to 3M90.  highdesertranger

( ; I think I would still be paying for that one if I had. Her hair was soooooooo sticky and wasted even with the 77 ; )

 

[accrete]

"accrete I see screws attaching the headliner ?"

The screws you see are on 1/4" x ~1" wide trim strips that are actually hiding the seams between three sections of 1/4" headliner board. The boards are screwed (hidden under trim strips) onto blocks of wood that are epoxied onto inner skin of fiberglass roof. There is about a 3 1/2" air space. Some reflectix and other insulation is up there.

 

[highdesertranger]

well, I didn't mean to spray her hair with it. lol. highdesertranger

 

[MrBob]

I currently have a Heng powered fan in my roof and it's been one leak after another with no support from the vendor. I'm ready to replace it and have looked at the Fantastic units but I'd be interested in hearing your experiences with it. Sounds like it didn't go well.

 

[Almost There]

I currently have a Heng powered fan in my roof and it's been one leak after another with no support from the vendor. I'm ready to replace it and have looked at the Fantastic units but I'd be interested in hearing your experiences with it. Sounds like it didn't go well.

Are you sure that the leaks are from the vent itself or is the water coming in from around the vent unit. Most (I'd say 99.9 %) of leaks are because of poor sealing during installation or old age of the butyl tape.

The gray butyl used by most RV manufacturers is only good for about 10 years before it degrades and needs to be replaced.

Unless you're absolutely certain that all the leaks are coming in from the interior of the unit, it might be worthwhile to remove and reinsert the vent after cleaning ALL the existing butyl and any other patching materials from both the roof and the vent unit and reinstalling the vent properly.

 

[accrete]

well,  I didn't mean to spray her hair with it.  lol. 

And I am SOOOOO Glad I was in the house preparing lunch when she did it : )
I know she can't blame me!
But I still had to pay for it.

haha.