Getting rust off a tin roof?

[Tenn_Blue]

Ok, starting to get the shop/barn ready for our bitter Tennessee winters :laughing: Really just doing some maintenance - replacing bad boards, renailing, etc. Was up on the ladder taking a good hard look at the roof...

My roof is the standard galvanized, corrigated tin, its an older barn so pretty heavy stuff. Anyway, its showing surface rust - about 1/3 of it is rusty red color instead of the galvanized silver. It about 40'x60', and slope is not too bad.

So whats the best way of treating/stopping the rust and protecting the roof?

I have a pump type house sprayer and was originally planning to paint the roof. Structure looks sound, so thought about using a sheet of plywood as a platform (to spread my weight out on the surface)and spraying from peak down. Maybe pressure wash or acid etch before painting? I know to secure the plywood so I don't go sliding off the roof....

So whats my best course of action?

 

[SandburRanch]

Ok, starting to get the shop/barn ready for our bitter Tennessee winters :laughing: Really just doing some maintenance - replacing bad boards, renailing, etc. Was up on the ladder taking a good hard look at the roof...

My roof is the standard galvanized, corrigated tin, its an older barn so pretty heavy stuff. Anyway, its showing surface rust - about 1/3 of it is rusty red color instead of the galvanized silver. It about 40'x60', and slope is not too bad.

So whats the best way of treating/stopping the rust and protecting the roof?

I have a pump type house sprayer and was originally planning to paint the roof. Structure looks sound, so thought about using a sheet of plywood as a platform (to spread my weight out on the surface)and spraying from peak down. Maybe pressure wash or acid etch before painting? I know to secure the plywood so I don't go sliding off the roof....

So whats my best course of action?

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Quote: WikipediA - Phosphoric acid may be used as a "rust converter", by direct application to rusted iron, steel tools, or surfaces. The phosphoric acid converts reddish-brown iron(III) oxide, Fe2O3 (rust) to black ferric phosphate, FePO4.

"Rust converter" is sometimes a greenish liquid suitable for dipping (in the same sort of acid bath as is used for pickling metal), but it is more often formulated as a gel, commonly called naval jelly. It is sometimes sold under other names, such as "rust remover" or "rust killer". As a thick gel, it may be applied to sloping, vertical, or even overhead surfaces.

After treatment, the black ferric-phosphate coating can be scrubbed off, leaving a fresh metal surface. Multiple applications of phosphoric acid may be required to remove all rust. The black phosphate coating can also be left in place, where it will provide moderate further corrosion resistance (such protection is also provided by the superficially similar Parkerizing and blued electrochemical conversion coating processes).

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Quart sizes of rust converter can be purchased at many home centers and hardware stores. Don't know about larger quantities you may need for a roof. Paint seems to adhere well on the projects I've used it on.

 

[Larry Caldwell]

The easiest thing to do is just pressure wash it to remove any loose dirt, and paint it with a latex designed for roof coating.

KST Coating - Snow Roof KST000SRB-20 Snow Roof Coating 4.75GAL

Metal Restoration for Building Owners - Conklin Company, Inc.

Generally they are too thick to spray through a conventional airless, though it might be possible to get a really big nozzle, and maybe remove the gun filter or replace it with a coarser screen. I just brush the stuff on with a 12" tar brush, or roll it.

 

[clemsonfor]

Yea go to the roof section at lowes or the home store. The stuf is applied with a stiff brush on a broom pole. It comes in 5 gallon pales and can be bought in silver or white. Various brands prices and formulations are availible. You just use a broom and brush leaves dirt and really loose rust particles. You can power wash too.

 

[tmajor]

Actually, until a tin roof starts to rust, it really won't hold a finish, well. In my area, some commercial painters, from S.C. come by every summer and paint the barn roofs, needing paint. They use silver/asphalt paint, which seems to last about 10 years, before it starts to get thin.

While it doesn't take them much time at all, it's worth it to me, ""cause, I don't want to get up there" and what they do in 1/2 hour, would take me days. I have a distant video of them doing my roof this summer. They did the barn roof, shed roof on the front of the barn and an adjacent garage for $500.

I can provide more information on the contractor, if you would like it.

 

[Soundguy]

phosphoric acid.. which will then turn it black.. then I'd wash down, and prime/ paint with rust control products.. ie.. etching primer and appropriate coating.

soundguy

 

[riptides]

Actually, until a tin roof starts to rust, it really won't hold a finish, well. In my area, some commercial painters, from S.C. come by every summer and paint the barn roofs, needing paint. They use silver/asphalt paint, which seems to last about 10 years, before it starts to get thin.

While it doesn't take them much time at all, it's worth it to me, ""cause, I don't want to get up there" and what they do in 1/2 hour, would take me days. I have a distant video of them doing my roof this summer. They did the barn roof, shed roof on the front of the barn and an adjacent garage for $500.

I can provide more information on the contractor, if you would like it.

Is the guys name Tom?

 

[tmajor]

No, it isn't. Pat and/or Jimmy Sherlock.

 

[ronjhall]

My barn roof is over 60 years old. All that has been done to it in that time, is 2 coats of Aluminum Fibre Coating. First coat was put on at 20 years when rust started to show up. Last coat about 10 years ago. When I did preventive maintenance. Removed all loose material and brushed on.