HIGH TOP Van attachment insulation/waterproofing

[Virgil Jones]

I am at the stage in the van build where I need to make another decision.  The lower walls and the van topper have approx. 2 1/2 inches of insulation.  I even cut small pieces of insulation (polyiso) to put in the wall frame ribs.  The upper horizontal van frame (below the roof) will also have pieces of polyiso shoved in it.  The entire area between lower van wall and the topper wall will have 1-by framing and house the electrical wires and some lighting.

The question is about the area between the remaining van roof (after the middle was cut out) and the upper horizontal frame.  The topper was attached to the body by drilling and screwing thru a metal strip, then the fiberglass top, then the roof, then into the frame.  There was no seal put between the metal strip and the fiberglass roof, although it is an extremely tight fit.

I will be dicoring above and below the metal strip on the outside of the topper.  However, the inside below the original roof line and above the metal frame is an open gap.  It's to complex of an area to just shove in polyiso AND that would not help if any of the screws do leak.  To simply cover the entire area with trim and just leave an empty space in that area all the way around the van screams condensation.

I have thought of filling it with caulk (a lot of tubes), or even just the expandable foam to at least give it insulation.
Please see the attached pictures.  You can make out a couple of the screws holding the topper as they come thru the roof and into the frame.  

Any thoughts?
Thanks, Virgil

 

[Bdog1]

You could wrap it with a boot. Rubber maybe. Or rubber with matching upholstery, like the seal between the cab and topper of a truck. Expanding foam is a mess. Nice topper by the way.....


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[akrvbob]

I'm looking at that same area to insulate on my GMC van. I'm thinking of using a water heater blanket and cutting it into strips and gluing it with spray glue along the length of that area. But I have two concerns, 1) because it is fiberglass, will the vibration send fibers flying and 2) is the vinyl backing on the blanket a vapor barrier, causing condensation.

I could wrap it in 6 mill plastic from a drop cloth and solve both problems.

 

[Virgil Jones]

I'm looking at that same area to insulate on my GMC van. I'm thinking of using a water heater blanket and cutting it into strips and gluing it with spray glue along the length of that area. But I have two concerns, 1) because it is fiberglass, will the vibration send fibers flying and 2) is the vinyl backing on the blanket a vapor barrier, causing condensation.

I could wrap it in 6 mill plastic from a drop cloth and solve both problems.

Bob, here is a short video of a build with the 1-by trim/framing I will be doing.  The problem I see is it leaves the covered area without insulation and seems like a ready made condensation trap.
I'm not quite sure how you would be installing the heater blanket.  will it be instead of the wood trim/framing or behind the wood framing, or?  Either way will you be leaving the van frame and roof area above the van frame empty or fill it with something?

 

[Virgil Jones]

Bob, here is a short video of a build with the 1-by trim/framing I will be doing.  The problem I see is it leaves the covered area without insulation and seems like a ready made condensation trap.
I'm not quite sure how you would be installing the heater blanket.  will it be instead of the wood trim/framing or behind the wood framing, or?  Either way will you be leaving the van frame and roof area above the van frame empty or fill it with something?

here is the shortcut to the video:

 

[TrainChaser]

I ran across this stuff when I was wandering around online, but it's too expensive for me. It's called Fiberfrax Ceramic Fiber Insulation, an aluminum silicate ceramic fiber.

But here, it comes in strips, and might serve a useful purpose for what you guys are doing: http://thermal-industrial-ceramic-p...lanket-strip-ceramic-fiber-blanket-insulation

Otherwise, I've never heard of it.

 

[Virgil Jones]

I ran across this stuff when I was wandering around online, but it's too expensive for me.  It's called Fiberfrax Ceramic Fiber Insulation, an aluminum silicate ceramic fiber.

But here, it comes in strips, and might serve a useful purpose for what you guys are doing:  http://thermal-industrial-ceramic-p...lanket-strip-ceramic-fiber-blanket-insulation

Otherwise, I've never heard of 

TrainChaser,
Thanks for the thought.  I am familiar with this product, and have used it to build kilns and glass furnaces.  Unfortunately it is very moisture absorbent and the fibers easily go airborne unless contained with something like a zircon/colloidal silica coating.  The surface of the coating and the ceramic fiber blanket would be prone to flaking minute airborne particles from the normal road vibration and rubbing in a van.  When I work with this I wear a respirator and cover my skin to prevent irritation.

 

[akrvbob]

I won't be putting wood trim there at all. My build will be VERY simple. But I do think insulation is important so the walls and roof will be insulated with 1 inch of polyiso.

Pretty hard to describe what I have in mind and it may not happen at all. I may just leave that long trim piece open and exposed if it needs too much work.

 

[flying kurbmaster]

expandable foam spray it in let it dry then trim it if you are still worried about condensation the a strip of thin polyso over the expandable foam and then your trim box, you could also just forget about he expandable foam and just install a strip of polyso, tape it down then install your trim over it , so you would have access to the back if you wanted to find a leak if there ever was one.