How foolish would I be to custom build a high-top on a van? (Read: Cut roof off)

[SoulRaven]

This sounds interesting but I'm not sure what you mean. Which material did you use for the shell? Do you have any pics?

We built a frame work of square aluminum tubing, trying to follow the original slopes of the front, rear, and sides.

We then took two sheets of FRP and sandwiched foam insulation board between them. We used plastic sheeting taped into a huge bag, and after applying spray adhesive, we used a shop vac to squeeze it all tight until it could dry. This created single strong, slightly flexible sheets.

We used flashing on all the seams, and once it was totally assembled, including the windows on each side, we coated the whole thing with plasti-dip rubber coating, then gloss white paint.

On the inside, we added another layer of foam insulation board between the ribs, to bring everything up flush with the ribs, and then covered everything up with white coroplast to create an easily washable headliner.

The contour of the roof, front and back were the hardest parts for us.

 

[David]

I've seen people build stuff with that expanding foam then shape it and finally do a layer of fiberglass over it. Maybe a mix of foam insulation board and then expanding foam to make the hard areas would be a easy way to go. Then once you have the shape ready cover it with fiberglass to give it strength and to make it water tight.

 

[SternWake]

Know that normal "fiberglass" resin will eat/ dissolve many foams.

"Normal" meaning Polyester resins which one can buy at home Depot or auto parts stores. Epoxy resin can be used on most any foam but is at least 2x the price and is less tolerant of nimrods mixing it incorrectly.

I see Cyrus Sutton's van often around here. He does not live in it unless he is actually travelling, Afaik.

The standard conversion van fiberglass roofs are made boat style, in a Mold with a "chop gun" which shoots fiberglass strands and resin into a mold in which the gel coat has already been sprayed. They will install some plywood or OSB in flatter parts of the roof and apply more fiberglass over it to stiffen it up. Very little fiberglass cloth was used in mine and only around the perimeter. Boat hulls made only from the 'chop gun', are significantly heavier and less strong than one which has many layers of Biaxial fiberglass cloth applied into the mold. I worked in a boat yard where only various molded parts, which were not subject to high loads, were sprayed with the chop gun. It is not easy to tell the difference between fiberglass Matt, and the chop gun on a finished product, as the strands are all haphazard on both.

But the chop gun is much less labor intensive, soooo...........

If I were to make my own hightop, I'd probably do 1/4" thick marine plywood over a lightweight wood or aluminum frame, and glass over that and paint over that, but it would still be more work than getting a roof from a junkyard and making it fit.

My fiberglass roof weighed about 220 Lbs gutted inside and without the Solar panels. It was very poorly attached by the conversion van company. Drywall screws. Fools. I want to hunt them down, but they are long outta business.

 

[sephson]

Know that normal "fiberglass" resin will eat/ dissolve many foams.

Spray paint also eats foam. There are a number of different coatings that we use in the theatre industry prior to painting scenery made out of foam. There is a good possibility that at least some of these foam coatings could be used to protect the foam from the fiberglass resin.

A "poor man's" foam coat can be found at any hardware store. Get some joint compound, add enough water to thin it down to the consistency of buttermilk, mix it up and either brush or roll it on.

I don't know that this will work with fiberglass resin, but it might at least be worth a test on a small piece of foam.

 

[David]

This is what I'm talking about when I say shaping with the expandable foam.. This guy has several videos for using it to build a wide body for a car then covering it with fiberglass.

It's pretty easy method to fabricate one off mock ups or to build a actual structure to then create a mold. If I attempted to build my own top, this would be the method I'd use to build the mock up.

https://m.youtube.com/user/kerrmann

As far as resin and foam, you just have to use the proper materials. Example, surfboards have been made for years using shaping foam with fiberglass covering.

 

[PeterG]

I think to get the strongest build you'd use a wood frame and then cover it with fiberglass. The wood could be reinforced before you glass it at the points where you are going to attach solar, roof racks, etc.

 

[bigdeepcreek]

I was wondering if it would be possible to somehow fasten a jon boat to the roof if you could not salvage a roof from an old van. It would be difficult to match the roof contours.

 

[highdesertranger]

a couple of points. whatever you do, keep your weight down. to much weight up high is a recipe for disaster. another thing if you believe you have the skills to build a high top, then making a pass though on a vehicle that doesn't have one should be a piece of cake. whatever you decide, good luck. highdesertranger