More unpleasant discoveries on the roof

Today I worked along the edges of the roof where I'd primed and painted the other day. That had a coat of topcoat and now looks pretty good.

Then I got on the roof. The roof vent is pretty rusty which it should not be. There is also rust on the roof where there should not be. It seems that the Rustoleum elastometric paint has actively damaged the roof by trapping moisture. I'm seeing rust on the flat areas, not just the joins in the metal. That is not welcome.

When I put the Rustoleum elastometric paint on, it was supposed to last 7 years. It had not even lasted two years, let alone 7.

After application, it cut the interior temperature of the bus down to outside temperatures. That was welcome. That only lasted for one summer though.

Mold and mildew grew quickly on the elastometric paint - so much so that it was definitely black in places. That should have been my cue to remove it.

Standing outside the other day after a heavy rain it was possible to see bags formed in the elastometric paint which when poked with a yardstick, burst releasing water. 

Going onto the roof today it was possible to see that the whole elastometric coating has broken up badly and is trapping water underneath. It's so bad that there are big patches of rust on the roof that were not previously there. The good news is the paint just lifts up with my fingers. A paint scraper should see a fast end to the elastometric paint. Whether I now have to redo the areas I've just painted remains to be seen. 

The elastometric paint has trapped moisture in the seams on the roof, which is not good. I might have to pull up all the seam sealants and redo them. The good news is I did buy a gallon of rusty metal primer and a gallon of white paint. 

What I'll have to do is to scrape the nasty elastometric nightmare off the roof, wire brush the rusty areas then brush the roof free of debris, wipe down with thinner and then spray on primer. I say spray because painting - even with a roller - doesn't get into the crevices and doesn't give an even coating. I can see a trip to Harbor Freight coming soon as they have a better electric sprayer than the one I used on the sides of the bus. It has a small high volume, low pressure compressor. That should be very helpful.

As for roof caulking, I'll stick with silicone caulk but I'll go over to the more expensive paintable caulk. That should solve all the problems though it does leave a huge bead. I'll have to figure out some way to reduce the bead side. Maybe there's some kind of non-stick spatula I can use to apply the caulk.

Looking for caulk I found some I'd bought not long ago. Trying to open it, I found the same issue that I'd had with the caulk the other day. It was rock solid in the container. Fortunately it was so rock solid that I didn't break the new caulk gun trying to squeeze it out.

The Rustoleum elastometric paint should not have cracked, peeled, formed bags full of water, caused rust or attracted mold/mildew. There should be a class action against Rustoleum for this kind of fraud. Before any cleverdick says I didn't prepare the surface correctly, it was brushed free of debris, washed with an industrial cleaner then rinsed and dried. That surface was as clean as it's possible to get.