New Roof Deck Fastener!

[IanT720]

In my hunt to figure out how to secure brackets to my bus to support my roof deck, I found a cool product!! Its called Box Bolt, basically a beefy drywall moly. That installs in a blind hole..

Theoretically, I should be able to install it from the outside, since my interior is finished, and it will secure it just as well as nuts and bolts but with the convenience of screws! Thoughts?

 

[somewhereinusa]

Looks like it should do nicely. Easier to install than a riv nut. I went to their website and specs look good. Just be sure to install into a rib not just the sheet metal.

 

[djdalfaro]

Looks like it should do nicely. Easier to install than a riv nut. I went to their website and specs look good. Just be sure to install into a rib not just the sheet metal.

I thought the top of the hat channel pointed inwards. Will there be enough flange material to secure it?

 

[somewhereinusa]

They do but, the flange, at least on my Bluebird is about !/2 inch wide. The factory installed roof rack is just installed with lag screws into the flanges.

 

[djdalfaro]

They do but, the flange, at least on my Bluebird is about !/2 inch wide. The factory installed roof rack is just installed with lag screws into the flanges.

1/2" seems pretty narrow when I think about how thick the actual bolt would be after taking into account the thickness of the sleeve. Maybe buy one and try it out on a similar sized piece of metal before buying them in bulk. But then again the bolt itself wouldn't see the bulk of the sheer stress.

 

[EastCoastCB]

If you go into just the sheetmetal it will deform very quickly. probably instantly.

 

[snonut]

Since the smallest they seem to make (5/16") requires a 5/8" hole I don't think these would work very well through a 1/2" flange. I would be more inclined to use a 3/8" self-threading screw through the flange material. It requires a much smaller drill ( than 5/8") and if you did one through each flange of the same rib, it would be as strong. IMHO


Bob

 

[EastCoastCB]

If you can, try closed end blind rivets in stainless.

 

[Iceni John]

What's their pull-out strength?

For when I secure my overhead kitchen cabinets into the roof ribs, I bought some Bollhof S25PB280 pre-bulbed Plusnuts in 1/4"-20 thread. Imagine a Jack Nut on steroids. Several companies make similar crossnuts, but the Plusnuts seem the strongest and best. Not cheap, but the best usually never is. They will go through the roof ribs from underneath, and I will make the entire cabinets from 6061 and steel angle so they're not going to ever move!

Jack Nuts are pathetic, Rivnuts are OK for light loads as long as their hole is exactly the right size and not even a few thou over, and forget about trying to thread into thin steel for a machine screw, or using self-tapping screws in hard steel.

For my roof's central walkway to which the eight big solar panels are hinged, I bolted up from underneath with stainless socket-head 3/8" bolts through each rib, 36 in total, plus another 36 5/16" bolts for the panels' struts, so I've got 72 stainless bolts for everything up there. It's solid. You could probably lift the whole bus off the ground by its solar panels!

John

 

[IanT720]

I've seen people on this site use coarse sheet metal screws before... So I have to imagine these are at least way better than those... The middle of my roof will be taking load too... Has anyone found smaller and cheaper "box Bolts"?

 

[MarkCHI]

What's their pull-out strength?

For when I secure my overhead kitchen cabinets into the roof ribs, I bought some Bollhof S25PB280 pre-bulbed Plusnuts in 1/4"-20 thread. Imagine a Jack Nut on steroids. Several companies make similar crossnuts, but the Plusnuts seem the strongest and best. Not cheap, but the best usually never is. They will go through the roof ribs from underneath, and I will make the entire cabinets from 6061 and steel angle so they're not going to ever move!

Jack Nuts are pathetic, Rivnuts are OK for light loads as long as their hole is exactly the right size and not even a few thou over, and forget about trying to thread into thin steel for a machine screw, or using self-tapping screws in hard steel.

For my roof's central walkway to which the eight big solar panels are hinged, I bolted up from underneath with stainless socket-head 3/8" bolts through each rib, 36 in total, plus another 36 5/16" bolts for the panels' struts, so I've got 72 stainless bolts for everything up there. It's solid. You could probably lift the whole bus off the ground by its solar panels!

John

I'm about to start attaching stuff to my roof. form what I understand the ribs are like hat channels (U shape with "flanges"). Some people seem to bolt through the flange (so they get several layers of steel).

If I understand from your post you drill through the roof, through the void in the ribs and the rib itself. IS that correct?

Do you use grade 8 bolts or would grade 5 suffice? Do you have a link to the bolts you use?

Thanks

Mark

 

[rossvtaylor]

I make solar brackets with holes spaced to line up with the two flanges on the ribs and I attach the brackets with two 1/4-inch closed end stainless steel rivets, one in each flange. The base plates on the brackets are 3x5 inches...so 15 square inches. In addition to the 2 rivets, I apply a bed of 3M 5200 Fast Cure adhesive/sealant. I can do this without having access to the inside of the bus. I have pull tested these brackets to over 2000 pounds of tension (and I've installed a couple hundred solar panels with them) so I've got confidence in this system. If someone were to have access to the interior, and replaced the rivets with 1/4-inch bolts, that would be at least as strong and probably stronger (since the tensile strength of a Grade 5 bolt is over 2500 pounds).

Hope this helps?

 

[Nawbdy]

Just so we have more information in one place about attachments to the roof, I did similar to Ross. I had access to the interior of the roof so I could use nuts and bolts. I had a helper for this. I did what I think Ross described but I used 5/16" grade 5 bolts, washers and nyloc nuts. I attached superstruts to the roof with 2 bolts at each rib, one bolt through the front rib flange and one through the rear rib flange. I believe I ended up with 48 5/16" bolts to attach 2 superstruts along the entire length of the roof. Each bolt goes through 4 layers iof sheetmetal when you consider 2 layers of roof sheetmetal, the rib flange AND the flanges of the longitudinal ribs that run between the ribs.

At first I thought I'd use 3/8" bolts but quickly realized that drilling a 3/8" hole at the 4 layer flange locations would completely destroy the flanges degrading the strength. 5/16" bolts were the largest I could use without cutting throught the edge of the flanges.