How to repaint metal side wall claddings ?

RD-Metal Unicoat, the best and easiest solution to give a new aspect to claddings while protecting them from corrosion.
Available in a wide choice of colors to match the visual identity of your business.

The products you need

Restore metal claddings on video

The problem

The coating of the metal cladding that protect the walls of numerous officies, warehouses and factories, are subject to weathering and different climates. The sun's rays, rain, wind, atmospheric pollution coming sometimes directly from the neighboring factory, are a daily permanent agression on these surfaces.

The coating start to change appearance after several years and sometimes very quickly depending on the location and orientation of the wall. The color changes or becomes chalky and whitish, rust appears - especially on the edges, and around bolts and fasteners; the original coating may also begin to peel or disappear leaving the metal exposed.

Whether it is a renovation meant to protect, or just a change of color, like to make it consistent with your company's graphic charter, our systems will give you the opportunity to give new life to the cladding.

Exceptions - Caution

Cladding coated with plastisol

In rare cases, RD-Metal Unicoat may not adhere to metal siding protected with Plastisol. We recommend performing an adhesion test first.

Cladding coated with PVDF

Consult the solution sheet "Repainting a metal cladding with a PVDF coating"

Metal cladding strongly rusted or located in a particularly aggressive environment, maritime or polluted site

Consult the solution sheet
How to repaint heavily rusted metal claddings or located in an aggressive industrial or marine environment ?

The solution

RD-Metal Unicoat

Bardage avec Metal Unicoat

RD-Metal Unicoat is a quick, simple and economical solution for renovating metal cladding placed in front of walls. It can be used for a simple makeover or for a more in-depth renovation,

RD-Metal Unicoat is the perfect choice to obtain long-lasting protection that can exceed fifteen years! It combines in a single product: anticorrosive properties, flexibility, good adhesion to different types of surfaces, UV and weather resistance.

RD-Metal Unicoat is one-component and water-based, so it presents no fire hazard, is safe and suitable for application to occupied buildings and will not affect occupants. It is available in most RAL, NCS and other custom made colors.

Recommended quantity and thickness

The thickness to be applied will depend on the environment and the type of project. However, considering that it is the surface preparation and the labor to apply the paints that represent the majority of a renovation budget, we generally recommend opting for the most efficient combination:

0.20 L per square meter or 200 square feet per gallon per 95 µ / 3.8 mils dry coat.

The total thickness obtained will be +/- 190 µsec / 7.6 mils.

Reminder :

For renovations to siding located in aggressive industrial and marine environments or if the siding is very rusty, consult the solution :
How to repaint heavily rusted metal claddings or located in an aggressive industrial or marine environment ?

RD-Metal Unicoat is part of the  Single Coating System product family developed by RD Coatings and can be used both as a primer and as a topcoat.

The  products provide the ability to solve specific problems using just one single product. These are easier, faster and very reliable solutions that do not compromise on quality in any way!

As our products are water-based, you avoid:

  • bringing hazardous products to the site and at the same time eliminating the risk of fire or explosion;
  • nuisance in the vicinity with unbearable odors during and after application;
  • emissions of harmful substances;

You respect nature, the applicator and your immediate environment.

Benefits and expected performance of the system

The system will have a long life if applied correctly and according to our recommendations.

The service life of the system is generally more than 15 years!

Many projects can benefit from the RD Coatings warranty. See the "RD Coatings Warranty" page for details.

One of the great advantages of the product is its ease of use. If there are touch-ups to be done several years later, using RD Coatings solutions makes it possible to carry out occasional repairs very easily and in record time!

It offers many advantages to all the stakeholders:

For the project manager/owner

  • Cost saving solution
  • No blasting required, economical solution
  • High performance and durable system
  • Eco-friendly
  • Water based, safe, no fire hazards
  • Virtually odorless, can be used in occupied buildings without disturbing
  • Wide choice of colors
  • Limited downtime, possible to apply within 24 hours

For the applicator :

  • SCS solution
  • Easy application
  • Almost no VOC
  • No isocyanates
  • High performance
  • Proven track record
  • No pot-life
  • One-component and quick-drying
  • No need for solvents nor thinners.

Getting ready


If the project is outdoor, avoid starting a job if it may rain within 3 hours after application. A minimum of 12°C / 54°F is recommended to have comfortable and safe working conditions. It also allows higher productivity.

Avoid working under direct heavy sunlight, especially in very warm regions where early-morning work or late evening are preferred.

Make sure there is no condensation on the surface before and during the application and the first hours of drying. If you are working indoor, make sure that the area is well ventilated.


RD-Metal Unicoat has no recoating window. In other words, should the works be interrupted because of a sudden change in the weather, they can be continued later without any problem!

Surface preparation

The most popular and fastest way to achieve a good surface preparation is to high-pressure wash the surface at minimum 180 bar or 2600 psi of pressure with a zero-degree angle oscillating tip. This procedure will remove contaminants, poor adhering paint and -rust from the surface. Remaining paint or rust that resisted may remain as the adherence is still sufficient.

Hand- or power tool cleaning (with abrasive paper or steel brush) is also an option and is advised when more detailed surface preparation must be carried out. 

Make sure that the surface is free of moss, mildew, oils,  greases and chlorides (salts). Rinse using an alkaline solution if not already mixed to the high pressure washer. Think of using biodegradable solutions that can be easily found and are very effective. 

Verify if the existing coating is still adhering properly and there is no loose rust. Never paint on top of a poor adhering coating.

Inspect and treat bolts

Inspect the bolts and screws if any. Defects should be repaired or replaced with new ones. Apply a spot coat of RD-Elastometal by brush after inspection. This will help in the inspection process and provide added waterproofing and anti-corrosion protection in these critical areas.


Check edges, especially when sharp. These are the weakest parts and quickly subject to corrosion if not treated correctly. Apply a spot coat of RD-Elastometal by brush. It will perfectly cover these edges and further protect them.

If any of these parts are showing advanced rusting, remove the loose rust, degrease, rinse and apply a layer of RD-Elastometal by brush. This will greatly contribute to the future success of the system.


An additional step which may depend on the location and the extent of the pollution would be to use soap and water to degrease the surface and remove any oils, pollutants and grease. Observe the surroundings to see if any chimneys are emitting fumes as they can cause an accumulation of contaminants on the surface.

Preparing the products

Products are ready for use. Mechanically stir the products for a few minutes before the application. Do not add any water to any of the products except when clearly specified.

Only if you are working in hot weather conditions, you may dilute the coatings with clean water to delay its drying. But do not add more than 3% of water in order not to diminish its anti-corrosion properties.


RD-Metal Unicoat and RD-Elastometal are best to be applied by brush on specific areas and airless sprayer on the main areas. If spraying is not possible, you can also brush the coating.  

Choose the type of brush according to the size of the objects to be painted.

Specifications for an airless application :

RD-Metal Unicoat: output of 180 bars / 2600 psi and a tip size between 0.013 and 0.015 inches.

Products can also be applied using the portable airless device Ultra Max from Graco. It’s a simple and effective method for small jobs or for touch ups on larger scale projects.

At the end of the job, clean your equipment with clean water or according to the equipment manufacturer manual.

We do not advise to apply with a roller because it is hard to build the prescribed thicknesses. If you decide to do so, you will have to apply multiple layers to reach the recommended thicknesses. We advise to use 14mm polyamide rollers or 3/8 inch nap rollers.

The application

Verify that the surface is dust-free with no contamination and no condensation.

If interrupted during the application we recommend that the areas to be coated be re-pressure washed or rinsed, usually if the surface has sat for more than 3 days without rain fall or located in a polluted environment.


If you intend to use a dry film thickness measure device, measure the thickness of the remaining coating or galvanized steel for later comparison after applying the coating system.

If you do not have this device, you can use a wet film gauge during the application that we can provide you with.

Apply the first layer of RD-Metal Unicoat on the entire surface.

Think of measuring your wet film thickness during the application as this will help you to figure out your future dry film thickness. Link to how to measure a wet film thickness

The final thickness is important and needs to be in line with our recommendations as it will be your guarantee for the long-term performance of RD-Metal Unicoat.

Let the paint dry for 4 hours before recoating. Depending on the weather, this can be shorter or longer.

Apply the full second layer of RD-Metal Unicoat on the entire surface the same way you did previously.

Eventually finish details such as metallic objects, corners and edges with a brush to make sure they are well covered.

After 4 hours of drying at 20°C, the coating is dry and rain-safe.

When working with a dry film measuring device, it’s time to control your total thickness. Subtract the eventual old coat layer and thickness of galvanization to know what you really applied.

VERS. S12-230228