Ceiling Rust Problem

[farok]

I thought I might have a roof leak since the top of the roof peak is riveted and there's a little rust. After taking down the ceiling panels, I found some definite evidence in the middle of the bus. What's the best way to deal with this?

On the outside, I'm looking at wire wheeling the seam, priming, then applying Dicor self-leveling lap sealant. While I'm up there, I plan to hit any other rivets I can find. I also plan to remove the emergency hatches and butyl tape and lap seal the replacement patches as well (from the ceiling panels).

Eventually I plan to do an elastomeric roof paint, but figured best to get this stuff done BEFORE the final roof coating.

On the inside, I figured I'd wire brush it (I have a cup brush for the angle grinder I was going to use for the rust on the floor), then treat with Ospho, followed by primer. Thoughts?

Is there a better way?

As always, thanks in advance!

Chris

[Mark_In_MA]

Just an observation, but look at where the rust is - it's an inch off the roof rib. There's still a white stripe by the rib before it gets really rusty. If it was leaking through the roof seam, I feel like it might travel down the rib, and rot the panel out from there, but that's not where the rust is right now.

What did you have up there for insulation before? I'm wondering if you had a leaky roof hatch that was soaking the insulation, and maybe that's whats rusting the roof.

Test with a garden hose, or set a sprinkler up there and let it run a while, and see what's wet inside.




Otherwise, I think your plan to treat the seam should work just fine.

[farok]

Thanks. The seam isn't right at the rib, but about an inch from the rib. I suspect the roof panels overlap a bit to the side as the rivets are also offset from the rib.

Anyway, I appreciate the agreement in the plan of attack! The hatches are also coming out, so regardless of the source, I think it'll be taken care of.

Chris