Mounting a cargo box on the roof?

I'd like to mount a cargo box on the roof of our RV to have some additional storage. I'm thinking of one of the boxes from Thule, Yakima, etc. that normally mount to a roof rack on a car. We have a '94 Tioga Montara.

How would I go about fastening it to the roof? Can I mount it directly to the roof with lag bolts or something like that? Since people mount satellite dishes, etc. on the roof I'm guessing that it's possible to bolt things to the roof, but are there only certain places that are strong enough? Any suggestions or information would be appreciated.


Senior Member
Mounting a cargo box on the roof?

As with any modifications to the roof, you will need to seal anything which punctures the roof very well to avoid leaks.

As for fastening it down, most roofs have a thin surface (wood or aluminum) over some kind of stronger rib structure. You will want to fasten your box to the ribs, not just through the thin skin (could rip out). However, you need to determine the size and material of the ribs to avoid damaging them. You may need to contact your manufacturer to get that information, or you might be able to get it by looking at the insides of the AC unit (either from below or above).

Finally, make sure that whatever location you choose does not interfere with anything which is already there (AC, vents, solar panels, antennas, etc). One presumes you have a ladder up to the roof, and close to that may be the most convieniant location, as carrying stuff around up on the roof could someday result in an 'instant skylight' :)

Finally, be aware what adding this will do to the overall height of your rig.