How to Paint Corrugated Metal Roofing
Corrugated metal sheets are a widely utilised construction material throughout the roofing industry. This highly versatile roofing solution is perfect for a wide range of structures from warehouses and commercial buildings to barns, stables and even residential projects.
With a potential life expectancy of up to 100 years in some cases, corrugated metal roofs offer impressive levels of durability, resilience and strength. To extend this lifespan, maximise structural stability and give your roof a sleek, professional finish, it is a good idea to add a layer of paint.
What’s the Best Paint for a Corrugated Metal Roof?
If you’re painting corrugated iron, it is key to pick the best kind of paint for the job. Different kinds of paint are formulated for different kinds of materials and structures, so you need to evaluate which formulation is best for your roof.
As a basic starting point, corrugated metal sheets typically require the usage of acrylic based paints which are graded as suitable for exterior use. This type of paint is perfect for refreshing an old worn roof and making it look brand new again. For new, untouched corrugated metal, acrylic latex paint is another practical option.
Within this base formulation, you need to look out for certain properties which will help to maximise the performance and resilience of your roof. These factors include:
- UV Protection – The sun’s rays are a fundamental issue for the condition of your corrugated metal roof. Pick a high-quality UV reflective paint that won’t be prone to cracking, flaking and fading when consistently exposed to UV rays.
- Coverage Area – To practically cover an entire roof space, it is key to ensure your chosen paint has enough coverage to complete the job with leftover product for future touch ups.
- Weather Resilience – Your corrugated metal roof will be exposed to all kinds of adverse conditions. It is key to pick a type of paint that can withstand varying temperatures and environments throughout the winter and summer months without succumbing to breakage, cracking and damage.
- Waterproofing – Finding a paint with good quality water resistance will help to lessen the chance of pooling, leakages and water damage.
- Ease of Application – For DIYers especially, picking a paint with easy application will make the job run far smoother and quicker with less mess and mistakes.
- Affordability – A high-quality paint does not have to break the bank. There are a range of more affordable options out there that still provide good levels of protection and durability.
- Chemical Composure – If possible, opting for a paint that is eco-friendly and free of toxic materials will greatly benefit your surrounding environment.
If you are unsure about whether your chosen paint is suitable for your roofing structure, it is always advised to seek advice and guidance from a professional.
Which Colour is Right for Me?
Specialist paints for metal roofing are generally available to purchase in a multitude of different colours. As well as visual appeal, the colour that you go for may also have an impact on the practicality and performance of your roof.
For example, light colours are far better at reflecting sunlight which can help to create a more energy-efficient and cooler environment. Darker shades tend to absorb the sun’s heat which means the building beneath may be warmer. If the building is situated in a very hot environment, opting for a light colour might be preferable whereas dark could be better for colder areas.
When choosing a particular shade, you may need to think about questions such as:
- What is the surrounding area like? (built, up urban area, open countryside, foliage and greenery?)
- Will this colour clash or coordinate with the existing colour scheme of the building?
- Will this colour boost the kerb appeal of the property?
- Will this colour collide with the look of rest of the properties/buildings in the area?
How Much Will it Cost?
The total cost of painting a corrugated metal roof will depend on certain factors such as overall roof coverage, type of paint used as well as preparation required. On average, the cost of painting a metal roof can run anywhere from £385 at the lower end to £3,855 at the very top of the scale. (source: gradedtradesmen.co.uk)
How to Prepare a Corrugated Roof for Painting
For a smooth application, you need to ensure the roof space is correctly prepped and ready. The very first step to this is:
Before applying any paint, you must give your roof a thorough clean, removing all possible traces of grime, grease, oil, rust, debris and dirt-build up. For this, you can simply use a brush and mild cleaning agent. Mix 1 tablespoon of dish soap with 1 gallon of water in a bucket to create a soap solution. Then, hose down the roof surface with clean water and dip a brush or rag into the solution and begin scrubbing. Remove the dirt, then rinse the metal using the hose once again once finished.
Alternatively, you could also use a high pressure power washer, then use a brush to finish off any tough areas.
Mould & Mildew
To tackle areas of mould and mildew, use a wire brush with a solution of chlorinated bleach and warm water. Always remember to wear adequate protective gear such as a breathing mask and gloves when working with bleach. Carefully read manufacturers instructions and research the products you are using to ensure they are safe for purpose.
Rust is not uncommon on metal roofing. You can easily remove surface rust by scrubbing with a wire brush and sanding with 80 grit dry or wet sandpaper. Any leftover rust can be neutralised by coating the section in a rust inhibitor.
If your roof is less than a year old, first treating with a metal degreaser will help the paint bond better to the surface for a higher-quality finish.
- Structural Stability
Before painting, double check that all roof screws and panels are tightly fastened and secure with no weak or vulnerable spots. Repair any faults and replace any damaged panels.
- Prepping the Area
To protect the surrounding area from splashes and mess, lay down a tarp or other protective material.
After cleaning, allow the metal to dry completely then apply a specialist galvanised-metal primer to your roof using a roller. This type of primer is typically solvent or acrylic-based. Ask for advice when purchasing if unsure to ensure that your chose primer works with your roof material and chosen paint.
If your roof already has existing layers of paint but has areas of removed paint from rust, mould or mildew removal, you can go over these areas too.
Carefully coat the front of the corrugated metal, moving back and forth, using long, continuous strokes. Use a substantial enough amount to cover the surface but not so much that the primer drips down.
Follow all manufacturer’s instructions and advise when applying then leave for the recommended drying time before painting.
How to Paint a Corrugated Metal Roof
Now you are ready to start painting your roof.
- Manufacturer’s Advice
The application advice and instructions on the back of the tin will of course differ from brand to brand. Take the time to read through all of the information and look for advised application methods as well as the recommended thickness for each coat.
If you are expecting large amounts of rain on the day of application and the next few following, it may be a good idea to put off the project until you have some drier weather. You don’t need to wait for blazing sunshine and blue skies; however snow, hail and rain can have an impact on the application, drying quality and overall finish of the paint so bear this in mind.
- First Coat
Fill a paint tray with your chosen paint and dip in a clean roller. Apply an even coat across the roof surface, ensuring you get into all of the crevasses and gaps too. Uneven sections will likely show up as the sun reflects off of the roof, so take your time to maintain a steady coverage.
You may also want to apply your paint via spray application for a faster and easier spread. Keep a steady hand, carefully working across your metal roof in even sections.
Once fully applied, leave the first coat to dry for the recommended drying time.
- Second Coat
Once completely dry, follow the same method to apply a second coat. Work thoroughly across the whole roof then leave to dry once again.
After the second coat has dried, your newly painted roof is complete! Two coats is generally the standard amount to reach a neat, protective finish however if three is advised, simply follow the same method one more time. There is no need to finish off the application with any sealing products as the paint will provide resilience and protection on its own.
Health & Safety
When working on a roof, it is always important to take the adequate precautions to keep yourself safe.
- Wear appropriate clothing – Wear suitable clothing that isn’t likely to catch, footwear with good grip and suitable PPE (dust mask, gloves etc) when working with potentially hazardous solutions.
- Follow ladder safety guidelines – Position your ladder on a flat and stable ground surface, placed securely against the roof structure. Have somebody else secure the bottom of the ladder and never stretch over further than you can safely reach when at the top. Take careful time climbing up and down, maintaining a sturdy grip and balance.
- Take care with paints, cleaning solutions & treatments – Always carry out suitable research and read through manufacturer’s instructions when working with paints and cleaning solutions. Some may be toxic or damaging to your roof so familiarise yourself with the product info before applying.
How to Maintain a Painted Metal Roof
Practicing adequate maintenance will help to keep your newly painted roof looking brand new look for longer. Regularly inspect your roof for damages and remove any excess debris to minimise the risk of scratching the paint.
Stick to simplistic products and tools when cleaning. Most general dirt and dust can be removed by a water, although for more stubborn stains a mix of 1/4 mild soap with a gallon of water should do the trick. Apply said solution using a soft-bristle brush, microfibre cloth or sponge, let it sit then rinse with clean water.
Avoid very harsh products such as wool scrubbers, sand paper, very high pressure washers, paint thinners and wire brushes as they can cause major scratching to the surface which will make the paint look old and worn.
Will I Need to Re-apply?
If you have chosen a good quality paint, constant re-application won’t be necessary. On average, metal roofs should be repainted around every 10 years. Indicators that your roofing paint may need a refresh include:
Painting your corrugated metal roof is a great way of providing durable protection whilst creating a neat, professional finish. With the correct products, preparation and technique, painting a corrugated metal roof can be a simple DIY task for homeowners.
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