how to paint my metal roof?

[1956chevy210]

Hi guys,

So I need to paint the roof of my shop. It is in decent shape, but it needs to be painted so it is not so unsightly. Its multiple colors!

About the shop and roof: The shop was built around 1989. Its not typical corrugated tin, it is purpose-made roof panels if that makes sense. I can't tell that its ever been painted, so I imagine it is the factory applied paint. The shop is 45x90, so I have a minimum of 8100 square feet to cover. Its actually a bit more since it is of course a peaked roof so its 3D instead of 2D. I figure I'm approaching 10,000 square feet!

My number one question is, what kind of paint should I use? Acrylic latex? Oil based? Most info on the net is all about painting bare metal roofs, not roofs that have a factory applied finish.

Also, how much paint do I need? Most paints look like they can cover 300 sq ft per gallon. So at 10,000 sq ft, I would need 33 gallons. If I want a thick coat my costs are gonna skyrocket. Dang, but understood.

Any help is appreciated!

1956chevy

 

[rusty1]

...for the time , effort and $, you could probly have new metal put on, ...maybe?
..then sell off the used tin, or re-use somewhere.

 

[The Cobbler]

I have a friend that used to make barn paint, normally the painters sprayed with airless . his was all solvent based at the time.

 

[aircommuter]

I am not sure how you got that footage with those dimensions. But anyway if it is painted now the biggest job is going to be scuffing the surface for good adhesion. One of the best paints for building metal is Kynar 500. If you can't get that then I would use Dunn Edwards evershield. Also acrylic urethane is very durable but probably not cost effective for a large area.

 

[MikeinNorthWales]

You know 45x90 is only 4,050 sq ft, right?

Sent from my SM-G935P using Tapatalk

 

[chaosracing]

I am not sure how you got that footage with those dimensions. But anyway if it is painted now the biggest job is going to be scuffing the surface for good adhesion. One of the best paints for building metal is Kynar 500. If you can't get that then I would use Dunn Edwards evershield. Also acrylic urethane is very durable but probably not cost effective for a large area.

You cannot field apply Kynar 500, its only factory applied. Kynar has a field applied paint, but its a latex version and is supposedly not as good.

You need to use an adhesion promoter if it was previously painted. When I was with a commercial roofing company, we had a ton of left over metal coil from jobs. Boss had us run off panels, then had his painter paint them after it was installed. Not sure what he used, I know it was solvent based. But that was 15 years ago and paints have changed alot since then. You should find a decent painter in your area and ask them for suggestions, or go to a real paint supply house and ask them.

 

[ard]

Be careful.... Painting a metal roof is NOT like paining a barn or stucco or wood siding.

The only thing worse that a fading roof is a roof with the wrong paint that needs to be stripped before getting repainted- THAT is a CF.

Agree on acrylic urethanes- I've been using sherwin Williams Acrylon 218 for several exterior metal apps, pretty durable. 10 years and still holding up very well.

Agree on the square ft. Even with a 5/12 pitch add 10%. You are under 5k sq ft

 

[DCarr2]

if it was my building....

Im going based upon the typical metal roof, a picture of what your working with would be nice.

I would rinse it with my pressure washer, then use the soap; function on my washer, and apply soap, then rinse it twice with my pressure washer.

Can you walk on this roof? My understanding is thats a big no no? If so that helps alot, otherwise you will need a boom lift.

I would go with an airless sprayer from Serwin Williams, they rent them out, and will even have a guy come out to your place and work with you (maybe) (they did for me, but then again I also spend $10-15K a year at SW)

with out talking to my paint people, 2 coatts of exterior duration should work..

also SW often runs 35% off sales, so keep that in mind, and if you set up an account with them (not a charge account) you can often get added discount... and an order that big, expect to wait a day or two...

try to stay away from oils, their messy, sticky and not very forgiving. not to mention youll need a respirator and glovess

 

[lostmind]

I used the coating for mobile home roofs. Power washed it first. Used white , still white years later. Put it on when it's hot , use roller , brush for trim. It comes in different grades , $75 - $95 for 5 gallons. Needs two coats , preferred one right after the other.
Once it's dry , it's tough to remove , sticks like Gorilla glue.
You have to be sure it won't get wet for 48 hours , same as other latex paints.

 

[1956chevy210]

Yeah, not sure what I was thinking with the square footage calculation (8100). For some reason I doubled 4,050. Oh well, 4,050 it is. That just cut my expenses in half! lol

It is not a steep pitch, I can walk on it comfortably.

Sounds like I need to pressure wash it first to get rid of the chalkiness, I was expecting that so its not a big surprise. Sounds like oil-based paint is out, and solvent based enamel is recommended. Right?

So what about exterior acrylic or latex?

Thanks!