Need advice on painting rusty parts on galvanized barn roof. Will alumacoat work? Best paint? Or is it best to replace metal or do nothing?

Rusty in places with no holes. Has had nothing done to it in 50 years. No paint or anything. How hard is it to replace or paint? Best way to apply paint? I have a sprayer.

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  • 6 months ago
    Favorite Answer

    Replacement is always the best option once the zinc is gone and the steel starts to rust but it's expensive and a PITA.

    To repair small sections you need to remove any loose rust mechanically, then passivate what's left of the rust. Apply an acid rust converter. It's not normally recommended on galvanised metal as the acid also eats the zinc, but if your sheets are bad enough, it's not really an option. When the rust converter has done it's job, wipe the surface down to remove any excess. Prime with a zinc rich primer if possible, regular red-oxide is fine otherwise. Then repaint with a colour of your choice. Use an epoxy metal paint, they will seal better and are more durable.

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  • Anonymous
    6 months ago

    Get yourself the 5 gallon pail of the aluminum rust coating and the big roofing brush which is sold right next to it. Take the roof coating to the paint section and have them put it in the Shaker for you. The stuff is way way too thick to spray. And there is no fast and easy way to do it you dip the big brush into the thick crap and brush it on good and thick. And if you put it on good and thick it will seal the leaks. If it's ridiculously Rusty you don't remove the old metal put a new piece of metal over it and nail it through the old metal and then brush the seams

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  • 6 months ago

    rustoleum would be good to paint the whole thing, daub the obviously rusty spots first, let dry,hose off dirt from the rest of the roof,let dry & paint,

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  • elhigh
    Lv 7
    6 months ago

    Apply rusty metal primer first, or even POR-15 or something similar to convert the rust to an inert form. Then come back with a couple of coats of exterior rated paint designed for roof exposure.

    If you intend to use metal roofing paint, apply the primer that product recommends, as conventional paint primers may not be the best choice.

    NOTE: Aluma-Kote only specifies a projected life of ONE year, so if you choose that route know that you're going to need to come back and hit it again, and again, and again. There are other products that have projected lifespans of seven and even ten years when applied properly and I bet that, while more expensive than Aluma-Kote, they aren't TEN times more expensive. In terms of performance per dollar and time required of you, you might do better to spend a bit more in exchange for a lot less effort and a more satisfactory result.

    Good luck with it.

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  • 6 months ago

    Rust-o-leum [brand] makes a rust remover product. use that first. then two coats of a rust inhibitor paint and the metal roof should be good for at least a decade

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  • Anonymous
    6 months ago

    Bubba Gubbins is right. Of if you can get it Hammerite can be applied directly to rusty surfaces. Unlikely as it may seem it does work and lasts.

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  • 6 months ago

    If it's only surface rust, use a rust inhibitor on the rusty areas, then paint the roof with any laquer based (industrial) enamel.

    Source(s): My 50 year old barn, complete with the original corrugated steel roof.
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  • 6 months ago

    If you don't get rid of the rust it will continue under the paint. You are better off just replacing it.

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