How To Paint Rusty Metal Roof? [5 Simple Steps]

Metal roofing is easier to install than shingles or rolled roofing, and it can last for 20 years or more. We must maintain the condition of our metal roof because it is prone to rust.  

Although most metal roofing is galvanised or coated to prevent rust, standing water and heat from direct sunshine can erode the roof’s protection.

Metal roofing is extremely robust and constructed to resist a lot of abuse, but it must be maintained on a regular basis. Many people with metal roofs wonder if they will rust. They certainly can, as evidenced by the fact that they have done so. Whether it’s steel, copper, zinc, or aluminium, every metal roof can rust.

It’s ideal to fix rust before it causes cracks or holes, but if you’re too late, urethane roofing cement, which can withstand harsh sunshine, can be used to produce an effective patch.

What’s the best way to keep the roof in good condition?

Metal rusts when it is exposed to water and oxygen, causing it to become a reddish-brownish tint. The good news is that most roofing manufacturers will apply a roof coating on metal roof shingles and panels. 

A roof coating is a liquid that is sprayed or brushed onto the surface of a roof to protect it from the elements, UV radiation, and even severe weather. Roof coatings, like hydro jetting, are excellent at eliminating obstructions and reducing damage to your roof. 

Roof coatings come in a variety of forms, including a metal roof coating that protects a metal roof from the elements indicated above as well as rust. So, how can you keep a rusted metal roof from leaking? There are a few procedures involved in removing rust and applying a metal roof coating. 

Roof Coating

Metal roof coatings can help with a variety of issues in addition to avoiding rust. Metal roof coating for leaks is very popular; commercial property owners often invest in roof coatings to avoid ponding water and roof leaks. 

The metal roof must first be cleaned in order for the roof coating to adhere to the metal roof’s surface. The roof coating can be applied right away if the metal roof is in good condition. If there are any cracks or other concerns with the roof, they must be repaired before the roof can be coated. 

The metal roof coating can be applied with a brush or sprayed. The roof coating must cure once it has been applied to the roof. 

The amount of time it takes for the roof coating to cure is dictated on the type of climate you reside in and the type of roof coating you employ.

What should you do if your metal roof has rusted?

If you have a rusted metal roof, you must first remove the rust and then prevent it from returning. You have the option of doing it yourself or hiring a professional to remove the rust from your metal roof. 

Similarly, a DIY paint job or a professional coating can help prevent metal roof rust from returning. 

A reputable expert is more likely to deliver a comprehensive, appealing, and long-lasting solution for your rusted metal roof, but a DIY approach will, of course, save you money. The ways for removing rust from metal are as follows:

  • Before recoating a corroded metal roof, it’s not necessary to remove every trace of rust. Instead, blast away all the loose, peeling rust with a powerful power washer or a light sand blaster. 
  • Dirt, mildew, and flaking paint can all be removed off the surface with water or sand. Try Trisodium Phosphate for obstinate metal roof corrosion that has resisted power blasting (TSP).
  • You could rent a power washer or a sand blaster, but using either on your roof is dangerous labour, and you may not be able to remove all of the metal roof rust. 
  • Hiring a professional to blast away at your rusted metal roof can be worth the money. If you hire professionals, make sure they utilise chemical remedies to eliminate and prevent mildew on the roof.
  • If you don’t coat the metal, you’ll probably end up with a rusted roof again in a few months. You can either paint the roof yourself or hire a contractor to do it for you or apply a specialty coating.
  • If you’re going to paint the roof yourself, make sure it’s clean and dry first. Begin by using a zinc primer to help prevent rust on your metal roof. 
  • For the top coat, specialised metal roof paints are available. Even so, you may need to repaint the roof every few years to keep the metal roof rust at bay.
  • An acrylic coating is the second choice. Although most of these coatings leave a metallic sheen, they can effectively prevent metal roof rust for up to ten years.

How to paint rusty metal roof?

Because metal roofs are continually exposed to the elements, they are prone to rust. Cleaning and repainting your roof will bring it up to date and prevent it from rusting further. 

The paint will not only improve the appearance of the roof but will also protect it from additional rusting if applied properly. A well-applied coat of paint can last for several years. 

For the greatest effect, use high-quality paint. If you want to repaint a rusted metal roof, follow these steps.

Step1 : Remove any loose rust

Using a wire brush, sandpaper, or a chemical rust remover, remove any loose rust. The idea is to make your surface as smooth as possible so that the new paint finish sticks to it well. 

Remove any loose paint from your surface that has chipped or peeled. To soften the sheen, lightly sand shiny surfaces. Sanding old paint that may contain lead is not a good idea.

Step 2: Make sure the surface is clean

Dirt, grease, and oil, as well as loose corrosion and peeling paint, can all affect paint adherence. Most surface filth may be removed with just soap and water or a household cleaner. 

Degreaser or denatured alcohol can be used to remove grease and oils. On previously painted surfaces, avoid using strong solvents. Solvents can cause old paint to soften, causing new paint to wrinkle or tear away from the surface. Rinse thoroughly and allow to dry completely.

Scrub any mould that has formed on the roof with a scrub brush and soap and water. This not only exposes all of the rust, but it also guarantees that the restoration materials adhere properly. A pressure washer could make the job go faster.

Step 3: Repair the surface

Replace any rusty screws or screws with worn washers with new ones. Repair the rusted hole before driving the new screw if the metal around any fastener has rusted and a hole has developed.

Urethane roof cement and steel roofing mesh can be used to patch holes and cracks, particularly those around rusted fasteners. 

Begin by using a putty knife to spread a layer of roof cement over the damaged area, leaving a surplus of 1 1/2 inches on both sides. To cover the space, use tin snips to cut a piece of steel roofing mesh.

Cover the mesh with roof cement, then cut a new piece of mesh, press it into the patch, and cover it with more cement. To make the repair as unobtrusive as possible, smooth and flatten the last coat of cement. 

Allow the roof cement to dry according to the manufacturer’s recommendations and the weather.

Step 4: Apply primer

Priming always aids in the creation of a smooth, even surface that is great for painting. Primer also improves adherence and reduces the probability of colour change. 

If you wish to prime, do so in several thin coats to avoid drips and runs. The type of primer to use is determined by the state of rust on the metal surface.

  • If there is a lot of rust on the surface

Use the primer to chemically transform rust into a waterproof, paintable surface if the surface still has substantial rust after all loose rust has been removed. 

To prevent additional corrosion, spray directly on the residual rust. To avoid runs and drips, apply numerous thin applications. This primer goes on clear and dries to a matte black finish. 

Topcoat with your chosen paint colour after 24 hours. If required, sand the surface lightly before applying the finish.

  • If there is some rust on the surface

If there is still some rust on the surface after all loose rust has been removed, use the primer, which provides improved corrosion protection for corroded surfaces as well as enhanced adhesion and concealing. 

To avoid runs and drips, apply numerous thin applications. After 8 minutes, the primer is dry to the touch, and in 15 minutes, it is tack-free. Apply a final layer of paint in the color of your choice.

  • If there is no rust on the surface

Apply primer or skip the priming stage if you were able to remove all indications of rust with a wire brush or sandpaper. Some paints are specially developed to offer excellent rust protection direct to metal even without a primer.

Step 5: Begin to paint

Paint on your well-prepared surface once it has been cleaned, dulled, dried, and primed suitably. Use a paint that matches the colour of your primer. 

It’s usually best to use primer and paint from the same company because they’re made to function together.  To avoid runs and drips, apply numerous thin applications.

You can read our blog on can paint freeze

When painting rusted metal, what precautions should you take?

Proper preparation is essential when painting corroded metal.

👉 Painting corroded metal is not only conceivable, but it may also generate stunning results if the rust does not extend beyond the metal’s surface. 

Paint won’t stop the corrosion and inevitable cracking of the metal if rust has eaten through it partially or completely, or if the piece has structurally weakened to the point that you can bend it by hand. 

Filling the pits with an auto body filler solution is your best option for recovering it; otherwise, the metal piece will need to be replaced entirely.

👉 While a primer might aid in the adhesion of paint to rusted metal, you must still remove as much loose rust as possible from the surface first. 

Otherwise, the loose rust will continue to rust away, forcing the dry paint layer higher until it blisters or peels away.

👉 Allow the metal to completely dry before applying the primer.

👉 Even minor rust does not adhere well to paint, and when it does, rust stains can flow through the paint coat and discolor it. 

A primer tailored to the amount of rust on your surface will aid adhesion.

👉 The primed metal item can then be painted with a variety of colours using either water or oil-based metal paint. 

Metallic hues like grey in a glossy sheen can play up the glamorous, futuristic aspect of metal, while non-metallic colors like hunter green, in flat or matte sheens, can give metal a back to nature effect.

👉 On galvanised metal, you should avoid using oil-based coatings.

Conclusion

Metal is used in furniture and decor both inside and outside the home, from entryway benches to patio chairs and fence posts. It is both elegant and durable. 

However, rust is the material’s Weak point. With enough oxygen and moisture exposure, any metal made of iron or iron alloys, such as steel, can rust. 

Paint is one approach to save these rusting junkyard finds and restore their appearance while adding a splash of color.

Leave a Comment