# Painting old, rusty galvanized roof?



## C_Brice

I have an old, worn, in need of repair pole barn out at my place. It's to the point of tear it down or get 'er squared up. I'm all good on what to do with the walls but I need to do something with the roof. Really the only option seems to be paint. Traditionally galvanized steel is a no paint surface without special prep. How about old stuff? What about the rust? 

Not looking to make it like new, just better than it is.

Thanks, CB


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## Bearfootfarm

Old metal is easier to paint than new.

I'd use Kool Seal on it
http://www.koolseal.com/


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## Evons hubby

I have used both regular paint and "roof coat" on old metal roofing with pretty good results. I like the fiber in the aluminized roof coat, as well as in the black, (nearly tar) roof coat. The fiber acts a bit like a tire plug in the old nail holes, and prevents leaks, and it sticks well. The roofs I have done have lasted a minimum of 20 years now.


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## blooba

C_Brice said:


> I have an old, worn, in need of repair pole barn out at my place. It's to the point of tear it down or get 'er squared up. I'm all good on what to do with the walls but I need to do something with the roof. Really the only option seems to be paint. Traditionally galvanized steel is a no paint surface without special prep. How about old stuff? What about the rust?
> 
> Not looking to make it like new, just better than it is.
> 
> Thanks, CB


Depending on how bad the rust is you may want to neutralize it or it will continue to rust under the roof coating and bubble it up.

http://www.por15.com/PREP-READY/productinfo/MRG/

Something like that will kill the rust before you paint it.


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## Micheal

I'll 2nd using the "aluminized roof coating" with the fiber in it. 
Both my pole barns were built when lead-headed nails were in vogue. Over time some of the lead disappeared and by using the "fibered" roof coating it preserved what was left and tightened down where it had loosened.


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## Lilith

Not sure if you are looking to keep the aged look of the metal, but .... a common approach to this in Sun Valley, Idaho (where movie stars like to live in Summer) is to age the metal roofing with Hydrocloric acid or sulpheric acid, this removes protective coatings, enamel, and rust. Rust will reappear in an even coating on the surface of the metal almost as soon as the metal comes into contact with water, both when washed down and in the air. it is then sealed with a clear enamel. The enamel keeps oxygen away from the metal and inhibits further rusting.
Another approach to this could be to acid treat, then the surface must be cleaned and degreased, paints and coatings do not bond well to dirty or greasy surfaces. A washing with a strong detergent followed by a through rinsing is required. The light "flash rust" that appears after washing can be removed with a cloth dampened with paint thinner or one of the commercial "surface prep" materials available. 

Painted items should be primed with a rust inhibiting primer and finished with two coats of a quality exterior enamel. Spraying is quite acceptable but I strongly recommend that the primer be brushed or sprayed and worked into the surface with a brush while still wet. Spray painting alone will not get the paint down into tiny pinholes and crevices but will only "bridge" these areas resulting in premature failure as the moisture and oxygen will attack the exposed steel.


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## RonM

Wire brush the loose stuff, then blow it off, then use a rustoleum type primer, then your rustolem paint, use a large brush to apply it...


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