Repainting a metal roof that’s obviously seen better days can protect against rust as well. The metal occasionally gets scratched from falling tree debris and hail. If your painted metal roof has suffered a lot of scratches over the years, repainting will help prevent rust from forming in the scratches.
It is possible to paint a metal roof. In fact, if you use the right kind of paint, it can last quite a long time and provide extra protection. While aluminum roofing is pretty impervious to corrosion, steel does not have the same properties. Paint can add protection against the elements and any problems they may cause.
You’ll be protecting the metal from rust, which is especially important if you live in an area near a coastline. Salty, humid air is notorious for causing corrosion on unprotected metal roofs. It also has a few insulating properties, keeping your home or shed a bit cooler in summer and more energy efficient.
Is it Worth Painting a Metal Roof?
Paint can add quite a bit of life to a metal roof. If you’ve ever taken a drive through farm country or a rural area, you no doubt have seen an old building or two with a metal roof that looks like nothing but rust. This is what can happen over the years when the metal is not protected. You’ll only need to repaint around every ten years or so.
Metal roofing is commonly made of steel, which can rust unless it has a protective coating such as paint. Even with paint, metal roofs do need to be inspected periodically to see if any tree debris or hail has scratched the paint through to the metal. The paint scratches need to be touched up to prevent rust from forming in the scratches.
What are The Benefits of Painting a Metal Roof?
Paint will definitely add to the lifespan of your metal roof. It makes them more durable and more able to withstand whatever the weather throws at them. It can also protect against the salt in the air if the building is located near a coastal area, where humid, salty air can cause corrosion in the metal and decrease its lifespan.
Besides protecting the metal, paint can add a layer of insulation, keeping the interior cooler on a hot day. With homes, this adds up to energy efficiency. Light colors of paint can cause the sun’s rays to be reflected away, further adding to the cooling effect.
There is also a sufficient assortment of paint colors available so that you can match many colors to those on other parts of your building, or at least get a color that adds an attractive look. With the right paint, the color will hold true over the years.
When Can a Metal Roof be Repainted?
If you have a new, unpainted roof, it’s recommended to wait at least six months before painting it. This is because the metal will have remnants of oils and other substances left over from the galvanizing process which will interfere with the paint adhering properly to the metal. The roof needs time to weather to get rid of any substances left on it so that you won’t have a problem painting it.
Most metal roofs already come with a color baked on at the factory. It’s important to get the right kind of paint so that it will adhere to this finish. Whether you’re repainting a roof with a lot of hail damage or one that has been scratched up from storm debris, it’s a good idea to keep further damage and corrosion from occurring by repainting it.
If you have a painted metal roof that is not the kind that has a factory color but was painted by the homeowner, you may need to remove that old paint rather than paint over it. If the old paint is faded or shows signs of flaking and chipping, it’s outlived its usefulness, so it’s best to take it off and paint the bare metal. Even the best finish can fade over the years, so it’s recommended to repaint every ten years or so, depending on the condition of the existing paint.
Can You Paint a Rusty Metal Roof?
If you have bought a place that has an older outbuilding, it may have what’s called a “tin” roof, using sheets of corrugated or flat metal as a roof covering. This kind of roof is not actually made of tin but is made of various soft metals that have been coated with a layer of tin and lead. This bare metal eventually rusts, sometimes with rust covering the whole surface.
To paint a rusty metal roof, the existing rust must be removed. It can’t be just painted over, or the rust will continue to erode the metal. You’ll need to choose a rather mild, dry day when you don’t expect any rain for a few days. If you can, you need to complete the rust removal and repainting all on the same day. If you have a lot of rust on the roof, you may need to get a helper to speed up the process.
Sweep off any debris or dirt off the roof. Then you’ll need to use a wire brush to get rid of the rust. It’s advisable to wear protective gloves and goggles to keep the rust dust from covering your hands or getting into your eyes because it will fly around while you work. Once you start, you’ll soon see why you don’t want to do this on a hot day.
Be sure to get all traces of rust off your roof. It may take a long time if you have a lot of rust, but any bit of rust left on the roof will start the corrosion process all over again. It pays to be careful and not to rush through this job.
For a roof with a lot of rust, you may well find a spot or two that has rusted all the way through. You can easily get a metal repair kit at most home improvement stores for small holes. If you have a large hole, however, you may have to replace the whole metal sheet.
It’s a good idea to inspect your roof for holes a day or two before starting to work on it. You’ll know just what you have to deal with and know if you need a replacement metal sheet or metal repair kit so you can have it ready before you start.
Can Galvanized Metal Roofing Be Painted?
Galvanized roofing can be painted. Usually, acrylic-based paint works best on this type of roof. If you have any doubts, you might ask a professional roofer to inspect your roof to find out just what you’ll be dealing with. He can also give you advice on other aspects of your painting job.
As mentioned above, for a new galvanized roof, you’ll have to wait at least six months to paint a new galvanized roof to allow any chemicals used in the processing time to be removed by the weather.
I have added this video that provides a lot of information on painting a metal roof and is a good idea to watch before painting your metal roof.
How Do You Prep a Metal Roof for Painting?
First of all, it’s important to find out just what kind of metal roofing you have. If it’s something you had installed, of course, you’ll already know, but if you’re painting a roof on a building you bought, you don’t have any way of knowing just what was used. An inspection by a professional roofer is invaluable in finding out what you have and how to deal with it.
Once you find out what kind of metal roof you have, you’ll be able to select the proper coatings for your paint job. A metal primer with a rust inhibitor is valuable for protecting your roof and keeping the topcoat in good shape. Choose a topcoat that will go with the primer. Your supplier can provide good advice on what to use for both. Be sure to tell him what kind of metal roof you have to enable him to better advise you.
You’ll also need a friend to help, even if you’re just painting a small shed roof. It’s always better to have somebody to help if you slip if nothing else. Try working from a ladder as much as possible. Once you’re on the roof, it’s always best to work with a safety harness of some sort.
Wear rubber-soled shoes to both provide sufficient traction and to keep from damaging the metal. Even with this precaution, metal roofs can be slippery, so a safety harness attached to a chimney or tree is important.
You’ll need to use a pressure washer to get all debris off the roof. This is especially important if you had to scrape off the rust, as rust dust will fly all over and you want to get it off. The pressure washer will also get rid of any mildew and help remove any paint flaking from an old paint job. Any flaking paint can be removed with a paint scraper or putty knife. Be careful not to damage the metal while removing old paint.
If your existing paint is old and faded or flaking, you may need to remove it all, not just the flaking sections. Once the paint starts flaking off in several places, it’s a sign that the paint is just too old to do the job and probably isn’t sticking to the metal very well. If you don’t take it all off first, any old paint left on may eventually separate from the metal, lifting off your new paint and primer. The primer will stick to bare metal better than it will old paint.
It’s also a good idea to take a scuffing pad and roughen up the metal a bit. This will allow the primer to adhere better. If you’re painting over old paint that’s still in fairly good condition, you may want to do this as well so that the surface is not too smooth. Now is a good time to install some roof venting before painting, check out my article Should I Install a Roof Vent for Shed Ventilation? for more information on roof vents.
What Type of Paint Do I Use for Repainting a Metal Roof?
Metal roofs can be repainted. In fact, it’s recommended to repaint every ten years, or more often as needed. The paint will show signs of wear after several years. Many people who have had exterior remodeling done will just want to change the color of their roofs to better go with the new color or colors they have chosen for the rest of the building.
It is important to choose the right kind of paint for your repainting project. You want paint that will adhere to the old paint thoroughly and also protect your roof. Acrylic latex paint works on both bare-metal roofs and those that have already been painted.
A metal primer with a rust protector is invaluable. You can also use a primer for galvanized metal along with an oil-based alkyd paint topcoat. There are many brands from which to choose. Even if you have a professional metal roof with a baked-on factory finish, you’ll want a primer to prevent rust and allow the topcoat to stick.
Basically, you want to look at the protective properties each brand offers. Water and fire resistance and UV reflection are all important things to look for. Don’t be shy about asking for advice from your supplier.
Tell him the specifics of your painting project and he can recommend products that other customers have had success with. Having local recommendations is important because these products have withstood weather conditions in your area.
As for tools, you’ll want rollers made for corrugated panels to ensure that the primer and paint will get everywhere and there won’t be any spaces skipped. You can also use a paint sprayer. This will not only help you get the paint into all the crevices but will also help you get an even coat of paint. It also cuts down on the job time and uses less paint.
How Much Does it Cost to Paint a Metal Roof?
This depends on market prices that are current at the time you buy your supplies. Usually, metal roof primer and paint will cost between 30 and 40 cents per square foot. You can usually get a five-gallon bucket of paint for around $170. If you have more than one paint source in the area, it doesn’t hurt to check prices before you make the purchases.
If you hire a professional painter, you’ll pay roughly between $1.20 and $2.72 per square foot. Since prices are usually figured by the roofing square, or 100 square feet, this comes out to between $120 to $272 per roofing square. In short, a professional paint job can run between $1,440 and $3,264. The slope of the roof will play into this cost as well. Many roofers will charge extra for roofs with a steep slope, as extra safety gear will be involved.
How Do I Paint a Metal Roof?
Choosing a day for painting is extremely important. You want a mild, dry day with no threat of rain. Summer days will make a roof so hot that you just don’t want to be up there. In addition, hot metal will make the primer paint dry so fast that it may be hard to get an even coat. Working on a roof in winter has its own problems. Any little bit of black ice can really wreck your day, and a day that’s too cold will interfere with the pressure washing.
Using a primer with rust inhibitor or paint sealant is extremely important. It will help protect your metal from rust, and also help the topcoat to adhere properly. You could have a problem with peeling paint if you neglect this step or get the wrong product. Choose a primer or sealant specially made for metal.
Using energy-efficient paint will greatly help reflect the sun’s heat from your roof. It will keep the inside of your building cooler and also limit the sun’s damage to the paint and roof itself. Using light-colored paint will help, but there are also paints that feature UV protectants to prevent damage from UV rays. There are also darker colored paints on the market that feature reflective properties. Investigate what’s available.
One big mistake that some homeowners make is to use some paint leftover from a previous project, such as painting their house, for a metal roof on a shed, or another outbuilding. You need to use primer and paint that is specifically formulated for use on metal, or you’ll end up with paint flaking off.
Once your roof is prepared, you can start painting. If you have a corrugated or seamed roof and you plant to use rollers, you’ll need some made for corrugated roofs to get into all the seams and low places. You can also use a paint sprayer, but if this is your first job with a sprayer, it may not be the best idea. It takes a while to get the hang of spraying the proper coat evenly, without getting it too thick and causing the paint to run. If your choosing to replace the metal roof check out my article How to Install Roof Strapping for Metal Roof for more information on strapping.
Painting your metal roof is an important job and should be done with care in all the steps. This is not the kind of job you want to hurry through. The more care you take prepping and painting your roof, the longer it will last and the longer the time the paint job will last between painting. It’s an important part of caring for your roof and the building underneath it.