Questions about a roof rack

[HardDog]

Hi all, I'm hoping that you guys can help me out with a roof deck I'm going to put on my skoolie. First off, my skoolie is a 1987 Hino mid engine, and the body is a monocoque so a bit different to the North American style that most people on here are used to. The roof doesn't have the hat section going all the way through it, rather a light roof structure resting on some quite beefy upright frames.
My idea is to weld 35mm square tube on top of the sturdy wall section and have it protrude up through the skin of the roof and sealed with silicone and dektites. I would possibly need 45°bracing pieces where I can manage to put them.
Can anyone see anything as to why this would be a dumb idea or have any better ideas I haven't come up with.

I've searched this site for anything to do with roof racks, and I haven't seen anything resembling my idea. I can't bolt them on the outside of the windows btw.
Cheers
HardDog

[Tango]

Sounds like a lot of roof penetrations. And getting them to stay sealed is tricky with all the flexing bus bodies experience. Hard to tell from the pix but I would be more inclined to attach brackets to those side braces between the windows. You could form some stout plate steel to come up above the roof line as the base for a rack or deck.


Not quite the same but a similar approach on mine...

[G Dub]

It sounds like Tango is on the right track. However, I'm wondering how his braces work against lateral forces. I assume there's more to the picture than pictured.

Have you been able to look up the spec's on your roof? Do you know how much weight it can take before any mods?

Most monocoques are fiberglass. Is yours? (Sorry, I can't tell by the pics.) If so, I'd be very careful about punching through it due to the danger of cracks from stress and movement (especially with square shaped or large holes).

Have you considered support beams inside? No [extra] roof penetration, just more material, effort and money - plus a bit less headroom (with some pretty spiffy fabrication on the curves).

[StefN]

So I've wondered about my rack as well, do I weld in the frame or bolt it through the roof. I have a 1990 13 window Thomas RE and was thinking of sealing the whole roof then bolting on a rack. With extra sealing/bonding for the bolted area. I could think of a good way of welding in the supports. I would love to see your when all done so post pics, please.

[plfking]

Originally Posted by StefN

So I've wondered about my rack as well, do I weld in the frame or bolt it through the roof. I have a 1990 13 window Thomas RE and was thinking of sealing the whole roof then bolting on a rack. With extra sealing/bonding for the bolted area. I could think of a good way of welding in the supports. I would love to see your when all done so post pics, please.

The OP is talking about a different roof construction than what you have on your standard Thomas. If you have the regular ribs that run from the floor of one wall, across the ceiling, then down to the floor of the other wall, you can bolt through the rib 'flanges' to support your rack.

I'm not a welder, but a few I work with recommended bolts instead of welding, due to the thinness of the roof sheet metal. I used a healthy glob of sealant on my bolt holes, and had no leaks even when Hurricane Florence dumped 5-7 inches on it over 3 days.

[johnforrest]

welding tubes on top looks tricky, and once the whole thing starts racking it might crack at the welds. Then you have all the big square holes to seal...

If you build a rack that spreads the weight out but stays a little flexible you can mount the whole thing with enough legs that have flat pads that match the shape of the roof. Position the pads to line up with roof supports. Much easier to waterproof. Just an idea.