Paintific » House Painting » How To Paint Rusty Metal Roof? [A Complete Guide]

How To Paint Rusty Metal Roof? [A Complete Guide]

When that metal roofing was installed ten years ago, it was in tip-top shape. The roof of your house was strong and ready to take on even the toughest challenges, including hail, rain, ice, wind, etc.

Of course, fast forward to today, and you probably still don’t have any problems in this department. After all, metal roofs are long-lasting. In fact, research shows they can last 30 to 50 years or more, depending on various factors.

However, how is your metal roof’s appearance these days? Even if it’s holding up nicely and keeping your head dry, the covering may not have the curb appeal that it once did. But what do you do?

Getting a metal roof replacement is an option, but it is also an expensive one. That’s why many homeowners choose to paint their roofs. It is a cost-effective solution that can make a rusty metal roof look new. Paint is often applied via a roller or a sprayer. Some people remove rust first, while others simply paint over it.

Before attempting a do-it-yourself metal roof painting project, are there questions you’d like answers to? If that’s the case, stay right here and read on.

can you paint rusty metal roof

Can You Paint Directly On A Rusted Metal Roof?

You can paint directly on a rusted metal roof all you wish. However, whether the paint sticks or not, that’s a different story. So, give these tips a look. Then, you’ll have ideas on hand, should a painting venture ever give you fits.

Research shows that some people swear by using vinegar when painting metal. They first clean the surface with soap and water. Then, after the piece dries, it is wiped down with vinegar. And no, you do not need a special type of vinegar, either. White household vinegar is all it takes, which you probably already have in your laundry room, kitchen, or garage.

In addition, if you don’t remove loose rust, that could lead to problems. Getting rid of the debris will call for sanding or scraping, but I’m not quite ready to talk about that just yet. There are a few other points to touch on first.

How Do You Prepare Rusted Metal For Painting?

Preparing rusty metal will vary depending on the project. For instance, you wouldn’t treat the preparation for painting a roof the same as you would an outdoor metal cabinet that needed to be repainted.

If an area features surface rust only, you may not have to do anything besides clean it with soap and warm water for the paint to stick. Meanwhile, if you have a pressure washer, that can do the trick too. Use its high-pressure spray to blast away dirt, mold, mildew, and more.

how to prep rusty metal roof before painting

Other tools that could come in handy are a wire brush or sander. When preparing anything metal to be painted, you’ll want to be sure that there are loose rust flakes. Leaving them in place can be a recipe for disaster, at least when it comes to your paint job.

Imagine for a moment that you paint your metal roof. Everything looks better than okay. However, you didn’t take precautions to remove metal flakes. Then, soon after you paint, a thunderstorm with wind and rain sweeps through the area.

Nothing major occurred. For example, the roof didn’t cave in or begin to leak, but the metal fragments you didn’t take care of have now been taken out of the picture. That isn’t too big a deal, but within weeks, the paint around those spots has peeled, leaving the roof in a visually unappealing state.

As you can see, the process for painting rusted metal isn’t always the same. So, do your homework and ensure you have all your ducks in a row before beginning your next project. All it should take is a quick Google search to get you the information needed to prepare rusted metal.

Do You Need To Prime Rusty Metal Roof Before Painting?

Metal primer isn’t a requirement for rusty metal roof painting projects. It is typically recommended, though, but ultimately, the choice is yours. One pro of using a primer is that it can prevent oxidation. Oxidation causes metals to rust and eventually decay.

Also, there is the matter of paint’s chemical makeup being less binding than a primer’s. As such, paints applied without primers often chip or flake off easier than paints with primers.

When it comes to galvanized metal roofs, a primer layer should always be installed. That will protect the metal’s zinc coating and keep it in excellent condition. Not only that, but the primer will prevent the paint from flaking.

So, you don’t always need primers when painting metals, but you should think long and hard about not using one because of various issues like oxidation and peeling or flaking that could arise.

Painting Rusty Metal Roof Step By Step

Step 1: Remove Loose Paint

When a metal roof is ready for a new coat of paint, loose paint needs to be removed first and foremost.

You’ll need a putty knife for the endeavor, and a ladder will also be required to get on the roof. Speaking of that aspect, always take your time and be careful when getting up and off the ground. Falls from ladders aren’t jokes. They can leave people with severe wounds like:

  • Soft tissue injuries
  • Fractures and broken bones
  • Traumatic brain injuries
  • Spinal injuries

The point is, bad things can happen if you aren’t cautious while working on a roof. So, when using the putty knife to scrape away paint and debris, wear safety equipment, tie it off, or take other measures to stay on the roof.

Aside from falling, you’ll also want to make sure you do not get anything in your eye. Thus, wear safety glasses or goggles to ensure a paint chip doesn’t obstruct your vision at a most inopportune time.

There is no need to worry about spots with paint in good standing. It doesn’t have to be removed. Instead, the new paint will adhere to it and bare metal spots, forming a solid membrane. But don’t get too far ahead of yourself. All you’re doing now is getting rid of the loose paint.

Then, once that’s done, move on to the next step.

Step 2: Remove Rust Patches

Don’t be surprised if you see small rust patches on your metal roof. By the time painting is necessary, these spots aren’t uncommon. A piece of steel wool might be able to help with this venture too. However, you might even need some vinegar or another household chemical to eliminate stubborn patches.

It doesn’t matter which path you wind up taking, you should always wear the appropriate safety gear. Latex or rubber gloves can stop chemicals from getting on your hands and leaving burns. Meanwhile, glasses/goggles are perfect for stopping flying debris from getting into your eyes.

You don’t have to, but this is the time when many painters scratch their metal roofs. Primer and paint sometimes stick better after this. Use 80 to 120-grit sandpaper or a wire brush to make the surface rough. All you have to do is simply run the pieces over the metal to lightly scuff them. That can help the primer/paint adhere to the roof, giving it a long-lasting finish.

Step 3: Clean And Wash The Roof

Begin cleaning your metal roof by walking around and picking up debris. You’ll want to remove things like tree limbs, leaves, and pine cones. Also, make it a point to look for tools workers have left behind. If plumbers, roofers, carpenters, or anyone else was on the roof in the past, there could be some surprises waiting for you. Is that a wrench over here or maybe a hammer over there?

Next is the washing portion of this step. The easiest way to get everything spic and span is with a pressure washer. However, there are other ways to tackle the task. For instance, a mop and a bucket of soapy water will work great in a pinch.

Then again, providing that getting down on your hands and knees doesn’t give you fits, a hand-held scrub brush and cleaning agent can be used to get rid of mold, mildew, and nastiness.

The entire metal roof needs to be done. That will remove any loose paint you might have missed. And don’t forget to get into cracks and crevices. You don’t want to miss anything that could cause you grief later.

So, take a little extra time to clean your roof correctly before giving it a fresh coat of paint. Failing in this regard can have you right back on top of your house fixing something that could have been avoided, and nobody wants that.

You can check this video for a more detailed guide on how to properly clean a rusty metal roof before painting:

Step 4: Drying

With all that hard work out of the way, it’s safe to assume that you’re ready to paint. Who wouldn’t be? Unfortunately, you have to wait a bit longer, though. While getting the metal roof clean, you also got it wet. Thus, before primer and paint can be applied, the surface has to be given time to dry.

Various factors may contribute to it taking more or less time for the drying to finish, but you should expect to take a break for at least an hour or so.

Step 5: Paint The Metal Roof

Finally, the time has come to paint your metal roof. If using primer, use a brush, roller, or sprayer to apply a thick coat to the entire roof. Usually, more than one coating is not necessary. Then, I hope you’re ready for another break. The primer needs to be allowed to dry for an hour.

After that amount of time has elapsed, you’ll have to check to see if the coat is fully dry. If everything is okay, you are ready to paint, but if there are still sticky and tacky spots, check every 15 minutes until the primer is cured.

I know; it’s boring, like watching paint dry, pun intended. Once the primer coat is all the way dry, you’re ready to apply a coat of paint to the roof. This will vary, depending on your method, but it can also be done via brush, roller, or sprayer. Be sure to put the paint on evenly and not too thick, or it may run.

After this initial coating, you’ll probably have to wait around an hour for it to dry. But, if you want a more accurate time frame, read the label on your paint can. It will contain helpful information about drying times and more.

After the paint dries, grab your tools and apply a second coat. Go over everything again, but be on the lookout for places you may have missed the first time. A third coat shouldn’t be necessary. Just apply paint to those spots in generous amounts.

You’re almost finished once the second coat is on and allowed to dry. The only things left to do are pick up and clean up. Then, after they’re completed, feel free to pat yourself on the back for a job well done.

Will Painting Over Rust Stop The Rusting Process?

paint rusty metal roof step by step

Sometimes, when only surface rust exists, paint can stop the rusting process. However, if the rust has spread across a wide area, this can be a lost cause. If things are too bad, the best solution might simply be to replace the metal roof, but if corrosion is just starting to show up, repairs might get you by for a while.

So, clean, remove rust, primer, and paint sooner rather than later when rust rears its head. That may be enough to stop the rusting process in its tracks and extend your roof’s life.

Can You Paint Rusty Roof Without Sanding The Rust Off?

You can do anything that you want to do. Who am I to tell you differently. Therefore, if you want to paint without sanding rust off, that is your prerogative. However, you could see better results with sanding. If loose flakes and particles aren’t removed beforehand, they can break free after being painted.

Then, you’ll be left with a polka-dotted roof featuring paint and shiny metal spots. Not only could that be unappealing to the naked eye, but if the coat of paint covering the roof isn’t solid, leaks might originate. Of course, by the time you find out, it will be raining, and too late because there will be water inside the house.

Just weigh the pros and cons of sanding and not sanding before you do anything. That will help you make an informed decision about which solution will be best for your particular situation.

3 Best Primers For Rusty Metal

Many consumers are intimidated by visiting paint stores or hardware stores where paints are sold. There are so many products on shelves that shopping can become stressful and overwhelming.

Don’t worry, though. I am here to make your life easier. The following are three of the best primers for rusty metal, and one of them could be just what the doctor ordered for your project.

1. Corroseal Water-Based Rust Converter

Corroseal isn’t going to remove rust. Instead, it is a water-based rust converter, which converts the rust into a stable compound and primes it for painting. Pros of this option include ease of use and application. It is also easy to clean up, thanks to the water-based formula. Meanwhile, some of the common cons associated with Corroseal are that it is expensive and has a chemical smell.

2. XIONLAB Rust Converter & Metal Primer

This XIONLAB Rust Converter & Metal Primer eliminates the need for scraping and blasting. It is a 2-in-1 product that converts rust into a stable compound and primes the metal surface. The roof doesn’t even have to be dry first.

According to reviews, the primer has no problem sticking to a damp surface. Perks you’ll experience with this product include versatile application methods, can cover large rust areas, and applies directly to rust or damp surfaces.

But there has to be at least one con, too, and there is. In this case, the drying process is critical. The primer must sit for two to four hours. Then, you’ll need to touch it to see if it is dry. After that, you’ll have to wait 24 to 48 hours before applying another coat.

3. Rust-Oleum 7769502 Rusty Metal Primer

Did you know that they make a primer for exactly what you’re trying to do, prime rusty metal? It’s true. Hence, if that’s something that piques your interest, perhaps you should look into Rust-Oleum 7769502 Rusty Metal Primer.

The one thing some consumers don’t like about this product is its lengthy drying process. It usually takes 24 to 48 hours for it to dry completely. However, that number could increase as well, depending on factors like temperature and humidity.

Of course, people like what Rust-Oleum brings to the table too. That’s why the Rusty Metal Primer is on this list. Some of the benefits you’ll notice with it include that it is easy to apply, manages tough rust, and doesn’t require dilution.

3 Best Paints For Rusty Metal

1. Liquid Rubber RV Roof Coating


This paint is white and reflects solar rays. Therefore, it is perfect for a house with a metal roof, as the coating can help the structure remain cool on the hottest of days. The paint is waterproof, so after the second coat is applied, you should be protected from leaks. This solution comes in a one-gallon can and is easy enough to apply by brush, roller, or sprayer.

2. HENRY HE587372 Roof Coating


White is also the color of this roof coating, making it a great choice to reflect heat. It is available in a 5-gallon bucket. So, be ready because that is going to be a lot heavier to carry up a ladder than a 1-gallon can.

You’ll need much of the paint, though, because two to three coats of the HENRY HE587372 are usually necessary. Consumers often boast about this paint being durable and long-lasting. It also forms a permeable membrane and doesn’t peel.

3. Rubberseal Liquid Rubber Waterproofing And Protective Coating


This Liquid Rubber Waterproofing and Protective Coating by Rubberseal is white. Hence, as with the two options above, it also reflects solar rays. So, your house will stay cool when it’s hot outside, and your electric bill might not skyrocket.

This product comes in a one-gallon container, and it covers approximately 50 to 60 square feet. It is waterproof, as the name implies, and offers excellent protection against rain.

Verdict

Painting a metal roof can be challenging if you let it. However, now that you have all of this information on hand, your next painting venture should be easy enough. So, go forth, paint, and soon your metal roof will look stellar and be ready to take on all the elements.

Leave a Comment

Your email address will not be published.