I have a bump out in front of the house with a sloped metal roof on it that is rusting. I want to fix this before it becomes a problem but I can not find reliable advice for my particular situation. The roof is sloped, painted white and made up of many 1.5 x 3 foot flat metal sheets whose seams are covered in some substance, not welded, that looks like thickly laid caulk but not soft like caulk. The roof is starting to rust bad, maybe 40% is now rusted, and I don't know if I can just sand the rust off without disturbing whatever the seams are covered with or if removing the rust is even necessary.
My question is, what should I use to "repaint" the roof and how should I prep the roof for said "paint"?
Edit 1 here is a pic of the roof:
Best Answer
First: yes you need to remove all the rust before repainting, or the paint will just flake off as the rust continues.
Next: you need to make sure that there's some "body" left after initial sanding/scraping of rust, or you might as well replace the sheets. You also need to verify that all rust is on the top, i.e. there's no leaking and bottom-side rust (or you'll need to fix the leaks).
Assuming all that went "ok," then sand & scrape all the loose rust off, and do your best to sand off the rest. Paint all exposed areas (with rust pits or not) with a "rust reducer" paint, available at any hardware store. Typically these go on white and cure black; they both reverse the oxidation (rust turned back into iron) and provide a good surface for painting. Then put down whatever color of metal-compatible paint you want.