I have several sheets of Corrugated Steel Roofing (see picture) from a replaced roof, and I would like to re-use them as a soffit under a porch, and paint them white or black.

How should I prep the sheets, and what type of paint should I use?

The soffits are obviously outside but not directly exposed to rain/snow or sun/UV: they are mounted with the "exterior" side down, not up as would be the case with a roof.

The panels/sheets are from a used roof and after some scrubbing/power washing they seem to be in good condition.

My thoughts were:

  • power wash & scrub moss etc...
  • light sanding to scruff the surface
  • maybe muratic acid, maybe primer?
  • paint with exterior acrylic, but maybe interior latex would work too?
  • to apply paint, use a roller? or brush?

No rain/snow, no sun/UV, but wet climate.

enter image description here

  • I would pay special attention to rust removal, priming, and painting of the existing screw holes. Even though this is weather protected, I would also reuse existing screw holes whenever possible to minimize additional punctures through the rust protection.
    – FreeMan
    Aug 18, 2020 at 12:50

1 Answer 1


How should I prep the sheets, and what type of paint should I use?

  • power wash & scrub moss etc. YES
  • light sanding to scruff the surface YES
  • maybe muratic acid, maybe primer? NO to both. Neither is necessary assuming those panels already have paint on them, which looks to be true. If your "light" sanding creates any bare metal areas, spot prime those.
  • paint with exterior acrylic YES
  • ...maybe interior latex would work too? NO why would you use interior paint for an exterior application?
  • use a roller? or brush? YES either/both, or spray
  • I have read that oil based paints are better for adhesion, And longevity, to metal surfaces, no ?
    – Alaska Man
    Aug 18, 2020 at 5:44
  • Clear and complete! Yes I was concerned with creating bare areas that would be ungalvanized, so I am glad you mention that. For primer: a rust primer? As for interior latex, only because of the price: there are some cheaper brands with which I have had great interior results.
    – P2000
    Aug 18, 2020 at 5:44
  • A special rust primer would not be critical but if that's what I had then I would use it. A bonding primer or oil-based grey metal primer would be great too. I would not use something like interior drywall primer. If I had a high-quality interior gloss or semi-gloss acrylic paint on hand... I would probably go for it rather than spend more $$. @Alaska Man, water-based paints have come a long way baby and in a protected location such as described will last for decades. No problem adhering to a properly prepared, previously painted surface. I would use exterior acrylic with a sheen. Aug 18, 2020 at 6:00
  • Just some feedback: this generally worked well, except on some spots the latex did not attach. When I marked a drill hole with a sharpie it peeled off. I had scrubbed and cleaned with baking soda (and rinsed), dried in sun, so I am not sure what the cause was. Maybe I missed a spot. Not a biggie, 2nd coat goes on after installation. Still I'd like to learn, if you have any thoughts on this. Thanks anyway!
    – P2000
    Sep 21, 2020 at 16:39

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