Installing a fan and skylight when there are square metal frames welded underneath the roof skin???

XYZdayz

New member
Any suggestion for this fan and skylight install? There is a 1 -1/2" square metal tube frame welded into the roof supports around the 14"x 14" roof penetration for the fan (also for a skylight)

I bought a frame adapter for the roof ribs and the instructions says "you only want the screw to engage the adapter and outer skin”. This would make it so the fan and the adapter frame float on the outer roof skin vs. attached to the square metal frame underneath. Does this better prevent leaks?

Should I use short screws to avoid penetrating this metal frame under the roof

or maybe avoid using screws altogether and just use an adhesive and maybe eternabond tape?
 

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Brad75

2013 NCV3
How much space is between the roof and that steel frame?

If it was my van I would shim the gap, pre drill then use self taping screws through the roof and into that steel frame.
 

hein

Van Guru
Did reply to your ebay message a bit ago. Based on better look at photos here I agree to inject windoweld in gap between metal frame and roof. Install our adapter. Let it all cure 12-24 hours. Place vent flange with butyl tape on adapter, Drill pilot holes through adapter, roof skin and top of frame for screws. Do not over tighten screws. Just snug and then 1/4 turn more. Seal over the top of screws, vent flange down sides of our adapter and onto roof with Dicor or Flexseal liquid.

All the best,
Hein
DIYvan
 

XYZdayz

New member
How much space is between the roof and that steel frame?

If it was my van I would shim the gap, pre drill then use self taping screws through the roof and into that steel frame.
Hi Brad, Thanks for the input! Appreciate it!

Is it better for preventing leaks to have the skylight and fan "float" on top of the roof skin vs. screwed into the rigid metal frame below. Seems the roof skin and metal frame move differently while driving and a rigid connection could result in gaps/leaks, or maybe the reverse is true, where it is better to use screws to connect the roof skin and metal frame around the opening? Had a massive leak problem before. Now renovating this 2005 Forest River MB cruiser.

To answer you question, there is a 1/8" to 5/8" gap between the skin and frame. I used PVC shims(molding), but may switch to flat aluminum in case the shims split from the screws. Also the Aluminum shims could be more secure if I end up not screwing into the metal frame.
 

XYZdayz

New member
Did reply to your ebay message a bit ago. Based on better look at photos here I agree to inject windoweld in gap between metal frame and roof. Install our adapter. Let it all cure 12-24 hours. Place vent flange with butyl tape on adapter, Drill pilot holes through adapter, roof skin and top of frame for screws. Do not over tighten screws. Just snug and then 1/4 turn more. Seal over the top of screws, vent flange down sides of our adapter and onto roof with Dicor or Flexseal liquid.

All the best,
Hein
DIYvan
Hi Hein, Thank you so much for your help and input! So kind and responsive. Appreciate it! (Sorry I emailed you back before seeing this post)

So in your opinion it is better to connect/screw the fan flange, adapter, roof skin into the rigid metal frame below? The metal frame is welded into the roof supports.

The question was whether it better for preventing leaks to have the skylight and fan "float" on top of the roof skin vs. screwed into the rigid metal frame below. Seems the roof skin and metal frame move differently while driving and would the movement and rigid connection from the screws result in gaps/leaks, or maybe the reverse is true, where it is better to use screws to connect the roof skin and metal frame around the opening? Had a massive leak problem before. Now renovating this 2005 Forest River MB cruiser. Thank you Thank you!!!
 

hein

Van Guru
Looks like a pretty significant gap between roof and frame. The frame really has no function (to support vent) if the space is not filled with some beads of adhesive. So either do that or remove it entirely. You are correct that some shorter screws that do not go into the frame would be best.

Also noticing that the vent or other skylight opening appears to be offset from center. We can do an offset adapter for you. Or maybe a two hole adapter that takes care of both openings.

All the best,
Hein
DIYvan
 

Brad75

2013 NCV3
Looks like a pretty significant gap between roof and frame. The frame really has no function (to support vent) if the space is not filled with some beads of adhesive. So either do that or remove it entirely. You are correct that some shorter screws that do not go into the frame would be best.

Also noticing that the vent or other skylight opening appears to be offset from center. We can do an offset adapter for you. Or maybe a two hole adapter that takes care of both openings.

All the best,
Hein
DIYvan

id still shim it. using short screws and leaving that gap there could potentially cause problems down the road if somebody walked up there and stepped close to the flange forcing the roof down where the tips of the screws hit the steel frame below and then get pushed back out through the flange. its highly unlikely but it could happen (murphys law) especially if he sells the van and the next guy doesnt know whats going on there.

another idea is short screws through the roof then spray foam the gap with a light weight foam so theres at least a cushion there in the event somebody does walk up there? again, all of this is highly unlikely but i dont like to take chances with my van when theres holes in the roof.

thoughts?
 

XYZdayz

New member
Thanks Brad and Hein,
You both get it. I am being extra careful to avoid leaks. This had a big leak problem in the back.

I previously filled one gap with butyl tape and the other gaps with PVC shims. The rigid shims seem to prevent the most movement. I think I'll have to leave the metal frames in at least in the back because the 14"x14" fan hole and 17"x23" skylight hole are side-by-side with flimsy roof skin in between.
Any thoughts on not using any screws at all? Instead maybe using adhesive (e.g.3m 4200 or 5200), and VHB tape for the bottom and then cover it with dicor lap sealant and then topped with eternabond tape?

How long could a customer adapter take to make for the back holes? I could maybe just glue on the adapter and then screw the fan flange into the adapter from the top with short screws (option A in attached drawing) or use a L-angle to screw into the inside of the adapter as a safety back up leaving space for movement (Option B).
 

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Brad75

2013 NCV3
Thanks Brad and Hein,
You both get it. I am being extra careful to avoid leaks. This had a big leak problem in the back.

I previously filled one gap with butyl tape and the other gaps with PVC shims. The rigid shims seem to prevent the most movement. I think I'll have to leave the metal frames in at least in the back because the 14"x14" fan hole and 17"x23" skylight hole are side-by-side with flimsy roof skin in between.
Any thoughts on not using any screws at all? Instead maybe using adhesive (e.g.3m 4200 or 5200), and VHB tape for the bottom and then cover it with dicor lap sealant and then topped with eternabond tape?

How long could a customer adapter take to make for the back holes? I could maybe just glue on the adapter and then screw the fan flange into the adapter from the top with short screws (option A in attached drawing) or use a L-angle to screw into the inside of the adapter as a safety back up leaving space for movement (Option B).
You could just go with adhesives and with today’s sealants you would probably be fine but without a mechanical connection youd be relying 100% on the adhesive, your prep and application. I would add a few screws just to be on the safe side.
 

XYZdayz

New member
Looks like a pretty significant gap between roof and frame. The frame really has no function (to support vent) if the space is not filled with some beads of adhesive. So either do that or remove it entirely. You are correct that some shorter screws that do not go into the frame would be best.

Also noticing that the vent or other skylight opening appears to be offset from center. We can do an offset adapter for you. Or maybe a two hole adapter that takes care of both openings.

All the best,
Hein
DIYvan
Hi Hein,
Thank you for the response above. Appreciate the help. The Sprinter van is a 2005. The 14.5" x 14.5 " hole for the maxxair Fan is in the center of the roof. Would it be possible to order an adapter for that one with the ribs cut in (see attached photos and drawing). I have butyl tape there now, but would replace it with the adapter.

For the other 14" x 21" skylight hole, could I buy a separate adapter for that. (see photos and drawing) If not could I buy the extruded PVC from you and try to make it. Also reached out via email if easier to communicate there. All the best. Mike
 

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XYZdayz

New member
Mike,

I am looking at skylights and fans as well. Could you tell me about choosing the setup that you did.

Best,
Stephen
Hi Stephen, Just seems most people are fans of the maxxair fan so went that way. Also had to get a custom skylight from https://www.eztopsworldwide.com/ because the skylight hole was already cut. I am bought this from extended family and working on refurbishing it. Going with the adapters from DIYVan.com and will use shorter screws because want to minimize the connection between the existing metal frames and the skylights. This is a very unique case and trying to avoid repeat of past leak issues. Not sure it applies to most conditions.
 
Hi Stephen, Just seems most people are fans of the maxxair fan so went that way. Also had to get a custom skylight from https://www.eztopsworldwide.com/ because the skylight hole was already cut. I am bought this from extended family and working on refurbishing it. Going with the adapters from DIYVan.com and will use shorter screws because want to minimize the connection between the existing metal frames and the skylights. This is a very unique case and trying to avoid repeat of past leak issues. Not sure it applies to most conditions.
Thanks for sharing Mike! So just to make sure I am understanding this you will have your skylight side by side with your fan?
 

XYZdayz

New member
Hi Stephen
I didn't have a choice as it was cut that way before I got it. I wouldn't choose to do it side-by-side. I am going to make the skylight fixed since it is a custom size and the fan is beside it.
 
Hi Stephen
I didn't have a choice as it was cut that way before I got it. I wouldn't choose to do it side-by-side. I am going to make the skylight fixed since it is a custom size and the fan is beside it.
Ah yes, that sounds like that was one of your only options. You are making the most with what you have.
 

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