I have a house in Ohio with an 85 year old metal roof over the kitchen. This roof has been painted many times. Currently it has a couple colors of paint showing plus a lot of rust, but no leaks. The roof is not a standing seam roof, but is made of attached metal rectangles.
I assume this roof is like everything else in this house, it needs to be treated gently.
I have been told to use Rustoleum’s Rusty Metal primer and then a top coat. Has anyone done this? Is this a reasonable primter? What sort of top coat should I use?
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I assume this roof is like everything else in this house, it needs to be treated gently.
Yup. What you have is a flat seam terne metal roof. The hard part of this type project is getting all the loose stuff off. A pressure washer may be a choice if you've got a lot of loose paint. Otherwise, elbow grease is all you want to use to gently remove all the loose paint. Do not sandblast or use drill attachments. Read the instructions on the primer. There are some primers on the market that arrest rust - others need the rust converted or removed. There should be a suggestion in the primer instructions on what is best to use over it, or go to a local paint store (Sherwin Williams, Benjamin Moore, etc.) and talk to the people that work there. They'll have a suggested system. Good luck.
I invented rust.
Roof painting is tricky. If the metal was tin plate or terne plate, OK. A good oil-base primer made specifically for roofs plus an oil-based topcoat. If the metal was galvanized, can be more difficult. The paint that sticks well to rusty bare metal does not bond well to galvanize and vice versa. Make sure the roof is bone dry before starting. The painter I use cleans the roof with wire brush and paint thinner. No water. When dry, prime with oil-based if the roof is not galvanized but use acrylic if the roof is galvanized. Topcoat oil with oil and acrylic with acrylic. I would be hesitant to use rustoleum. You're lucky to get 5 years service from a paint made for use as a roof paint. Its a good paint, but I'm not sure how long rustoleum would last.
Rustoleum doesn't seem to hold up well to weather. On a small metal shed, I put two coats of Rustoleum primer followed by two top coats. This summer was the second season for it and the roof and south side are already showing lots of wear.
Next time I will probably prime with Rustoleum and topcoat with standard exterior paint.
Guess I'll keep using Rustoleum for my lawn chairs, but not for items exposed year round.jt8
I like the stuff that has the tar in it -- I painted our barn roof 8-9 years ago with a rustoelum type paint and it just did not hold up -- went back with the 40 gallons on the silver roofing paint that has tar in it (you have to use a 1/2" drill with the joint compound mixing blades to stir) and it is holding up great. ABC roofing sells this and it is called/made by Mule Hide
NEVER, EVER, EVER put any asphaltic products on terne metal. They are corrosive to it. They will stop the leak for a while. Meanwhile they are eating the metal away below. I don't know about galvanized.
I invented corrosion.
I've had my roof done and seen at least 5 others done recently. There have been about 10 done in my neighborhood in the last 5 years. One still looks good. Five are acceptable and four are total failures. A couple people had the whole roof redone with new baked-on metal roofing. Got at least 10 different opinions about what was good or bad. The general opinion was that galvanized is a pain in the neck. Several people told me red oxide primer should never be used on galvanized. One insisted only acrylic was any good. I have that on one of my roofs and don't like it. I have not tried the tar stuff.