How to Remove Rust From Metal Shed Roof

[Philip Nowak]

Hi BP Community, anyone have any tips or experience removing rust from a metal shed roof? 

I tried TSP as well as Naval Jelly, letting them sit for the appropriate time in the recommended application temperature range. I then scrubbed the roof vigorously with a nylon bristle brush and a metal bristle brush.

Nothing helped beyond some light surface rust as well as making the unaffected areas appear cleaner. After 2 hours of rinse and repeat, I packed everything up and called it a day.

I don't know how old the shed is or what kind of metal it is as I just purchased the property in 2013. The shed is about 13 feet by 21 feet. What's interesting is that the inside of the shed roof is in pristine condition with no penetration of the rust from the outside...yet.

My goal is to preserve the shed from further deterioration. My options are to replace the roof or remove the rust, prime, and paint. I'm apprehensive about trying to sand it with a power sander as the roof has an uneven texture on it. Any ideas?

Thanks,

Phil

[Jassem A.]

Could paint the roof. I'd go with a gallon of gloss Rustoleum paint and 4" brush total cost maybe $35

[Philip Nowak]

Thanks for the suggestion, @Jassem A.. You think it's okay to just paint over the rust with rust inhibiting paint? 

[Jassem A.]

@Philip Nowak

Yes it should not be a problem.  If you left it like it is now it would probably be years and years before the rust would eat a hole in the roof anyway.

[Robert M.]

I am not suggesting doing this for the roof but two ways to convert insoluble iron oxide( rust ) to a soluble form that is removed with a water rinse is to use either oxalic acid ( 5% solution on the rust for about 30 minutes( can wet towels so it adheres and does not run off) in water or a commercial product called "Iron Out" which is sodium hydrosulfide I think.

[Julie Haveman]

Try The Works toilet bowl cleaner!

[Arlen Chou]

@Philip Nowak go to Home Depot and by some corroseal rust converter.  It converts the rust to magnetite.  It will also prime the surface for you and you will be able to paint the surface.

Have fun,

Arlen

[Tariq B.]

Do not just paint. Go to the store grab a bottle of rust reformer this will keep the shed from getting worse. After you have sprayed that and let sit then you can either sand or just paint. Your choice for whatever finish you want.

[Matthew Paul]

ITS A SHED .   Lightly scuff the surface and paint with oil based enamel .  Put it on with a roller .   It will be YEARS before you have to mess with it .      

[Philip Nowak]

@Matthew Paul @Tariq B. @Arlen Chou @Julie Haveman @Robert M. @Jassem A. Thank you to all of you for the suggestions. 

[Christian Bors]

@Philip Nowak What did you end up doing? Do you have picture with the result?

[Philip Nowak]

@Christian Bors The cold weather beat me to it. I am waiting until it warms up in the Spring. 

[Dan Waugh]

I'd just hit it with the rustoleum rattle cans or roller pain't if it's not supportive of weight. As long as it's not raining, it'll take hours to set but it'll set. I'm a welder, so I'd probably heat it with a torch to set it faster but easy to burn the paint if you're close or slow. It'll be so out of date by the time it finally rusts through. I'd be more worried about the screws than the sheet metal. Those rust the fastest because it's corrosion "squared". They're standard metal screws, not galvanized, not painted.

[Philip Nowak]

@Dan Waugh You're absolutely right. The screws are completely rusted over.

[Dan Waugh]

Originally posted by @Philip Nowak:

@Dan Waugh You're absolutely right. The screws are completely rusted over.

 Rust is cancer for metal. If you're that adamant about keeping the shed as long as possible, pick a warm-ish day and beat the snow. Looks like it's been there for more than 4-5 years or so. Another season won't hurt, I guess.

[Matt K.]

I've used a product called ospho in the past and its worked well. You'd need to coat that with paint afterwards also...

[Don Meinke]

I would think you would want to put a thicker coating on there than paint.  They make an eslometric coating used alot in mobile homes and such things.  Think you can get a silver or white finish color.  I have never used it but thought it was more like thin tar and you mop it on.  Supposed to reflect heat too and make inside cooler in summer.  Spraying some rust converter on first may be best,,,especially for the benefit of the screws and there immediate holes.  Most big box stores would carry such a roofer product,,,as well as most all lumber yards of traditional flavor.

My concern would be,,,can you walk on that without dimpling?  Do you have to cover it completely from the edge standing on scaffold?  IF so a long handle roller with a real shaggy coveer might work,,,or ask where you buy it.  Maybe a mop attachment for the heavy duty extension handle.  I would try to stay away from any coating 'sprayed' on because it has to be really thin to go thru.

  Your doing a GOOD thing,,,getting in front of this.  And yes waiting till day time and NIGHT time temps are back up to acceptable and not TOO hot.  'here' we are looking at May or very early June

[Nicholas B.]

You could overlay it with OSB and glue down a layer of rubber roofing. You could even lay out some purlins and install real metal roofing. Either of those will outlast the walls, which are likely already rotting at the bottom. 

Those sheds are so cheap though - literally $400-$500. Yours is already rotting through. I'd just replace the shed, but buck up a couple hundred more dollars for resin this time.

If you're trying to go cheap, but just can't live with the rust, just hit it with a rust encapsulator. It won't do anything to stop the worst of the rot (it's too far gone for that), but it will make it look better for a couple of years.

[Holly Kershaw]

I used elastomeric roof coating on my rusted, leaking flat roof. I cleaned it first with metal deck brush, let it dry, then applied 2 coats with a long nap roller. Two years later in a harsh climate and still no leaks and it looks good. 

If you have a menards by you, you may want to check into their metal roof panels and just replace the roof on the cheap.