Home How to renovate corrugated metal sheets roofs?
Renovate and extend the lifespan of metal sheet corrugated roofs that have issues with waterproofing, rust, or delamination.
RD Coatings offers a simple and highly effective solution that has demonstrated exceptional performance worldwide, in various climates, for over 25 years!
The products you need
RD-Elastometal 
High performance elastomeric coating combining superior anti-corrosion and waterproofing...
High performance elastomeric coating combining superior anti-corrosion and waterproofing...
RD-Roof Fleece 
Reinforcement mesh used in waterproofing systems for roofs, decks and screeds.
Reinforcement mesh used in waterproofing systems for roofs, decks and screeds.
RD-Eco Powerclean 
Powerful biodegradable alkaline concentrate composed of anti-flash rust additives for cleaning...
Powerful biodegradable alkaline concentrate composed of anti-flash rust additives for cleaning...
How to restore your metal roof in videos
Introduction
Surface preparation
Application
The problem
Metal roofs made of steel sheets or corrugated iron are commonly used to cover warehouses, factories, houses, and other buildings.
Continuously exposed to extreme weather conditions, they face many challenges.
Indeed, the sheets continuously expand and contract under the effect of heat and cold, while resisting rain, hail, snow, UV rays, pollution, and erosion.
Under the influence of these external conditions, rust and leaks eventually appear, sometimes quickly. The original coating peels off, which can cause significant damage: damaged stocks and production tools, damaged furniture, etc.
The solution
RD-Elastometal
RD Coatings offers a simple, quick, and highly effective solution with RD-Elastometal, a high-performance, water-based elastomeric coating.
This unique product combines superior anti-corrosion and waterproofing properties. Thanks to its UV resistance, tt can be used as both a primer and a finish. It is also frequently applied to bridges and other metal structures in marine or industrial environments.
When applied to a steel sheet roof, RD-Elastometal forms an elastic protective membrane with a rubbery appearance. Its permanent elasticity, exceeding 200%, even at low temperatures, allows it to follow the expansion movements of the metal under the influence of heat.
RD-Elastometal is available in various colors.
Being water-based, RD-Elastometal poses no danger or fire risk during application. Virtually odorless, it is ideal for application on occupied buildings without inconveniencing the neighborhood.
With performance typically exceeding 15 years, RD-Elastometal significantly extends the lifespan of steel sheet roofs by protecting them against corrosion and making them waterproof!
Key advantages:
- Single-component product, ready to use;
- Simple and easy to apply solution;
- Fast drying and reduced downtime;
- Dryfall;
- Wide range of colors available;
Safety and environmental benefits:
- Water-based coating/paint, no solvents or thinners;
- No introduction of hazardous materials on site, eliminating the risk of fire or explosion;
- Very low VOC (volatile organic compounds) levels;
- Virtually odorless, limiting nuisances during and after application;
- Minimized loss and waste during and after application;
- Prolongs the lifespan of surfaces
Option: RD-Sunguard - solar reflective paint / cool roof
The application of a high solar reflectance cool roof paint, RD-Sunguard, offers several advantages:
- Significantly reduces surface temperature and heat transfer through the roof;
- Reduces the energy consumption needed to cool the building;
- Naturally lowers the temperature in spaces directly under the roof/surface and with low insulation;
- Increases the productivity of solar panels;
- Extends the lifespan of roofing materials.
Discover the possibilities with our Solution Applying a heat reflective coating to a roof.
System
Corrugated metal sheets roof with a pitch of minimum 4%
| Product | Consumption | Dry film | |||
| 1st layer | RD-Elastometal | 0,40 kg/m² 130 s/f-g | 175 µ 7 mils | ||
| 2nd layer | RD-Elastometal | 0,40 kg/m² 130 s/f-g | 175 µ 7 mils | ||
Special cases :
1/ In the case of stagnant water, or gutters for example, it is necessary to reinforce the system by including RD-Roof Fleece in the first coat of paint.
| Product | Consumption | Dry film | |||
| Primer coat | RD-Elastometal + RD-Roof Fleece | 0,40 kg/m² 130 s/f-g | 175 µ 7 mils | ||
| Finish (minimum 2 coats) | RD-Elastometal | 1,60 kg/m² 30 s/f-g | 700 µ 28 mils | ||
2/ If your roof is located in an industrial zone, and subject to high concentrations of chemical agents (chimney gases, chemical fallout, etc.), we recommend applying one or two coats of RD-Hydrograff HP Clear Gloss as a finish.
| Product | Consumption | Dry film | |||
| Finish | RD-Hydrograff Clear Gloss | 0,15 L/m² 270 s/f-g | 60 µ 2.4 mils | ||
Application conditions and work preparation
Environmental conditions (general requirements):
- Minimum air and substrate temperatures: 10°C / 50°F for 24 hours during and after the application.
- Maximum surface temperature: 55°C / 130°F.
- Maximum relative humidity: 90%.
- Surface temperature must be at least 3°C / 5°F above dew point.
- No threat of rain for at least 4 hours.
/!\ Notes
- There must be no condensation on the surface during application and drying. Caution when working at the beginning or end of the season!
- Overnight drying between coats is generally recommended. However, drying rates for water-based coatings depend on temperature, humidity and wind.
- From 15°C / 59°F, working conditions are comfortable and enable higher productivity.
- If the project is located in a very hot area with very intense sunshine during the day, avoid applying the system when the sun is most intense on the surface, and prefer to work early in the morning, late in the afternoon or in the shade.
Good to know!
RD-Elastometal have no recoating window. In other words, if work has to be interrupted due to a sudden change in the weather, it can be resumed later without any problem! Just make sure you clean up according to the time elapsed.
Surface preparation
The surface must be clean, dry, degreased, and free from any contaminants. Rust or loose paint must be removed.
The most convenient and quickest way to achieve this is to clean the surface using a high-pressure washer equipped with a zero-degree rotating nozzle. Minimum pressure: 180 bar / 2600 psi, to be adjusted according to the condition. This method will remove contaminants, rust, and paint that no longer adheres to the surface. If old paint layers persist after cleaning, it means their adhesion is sufficient and they can remain in place.
Hand cleaning with a wire brush or mechanical brush is recommended when more detailed surface preparation needs to be carried out on objects located on or near the roof, such as access ladders, ventilation, access doors, bolts, fasteners... that are rusted.
Moss and mold must be removed down to the root using appropriate cleaners.
RD-Eco PowerClean
Using it just before application ensures that the surface is properly clean and degreased. Especially in the presence of persistent dirt, oils, greases, pollution on the surface, or in case of a significant lapse of time between surface preparation and the start of application.
Immediate Environment
Check for the presence of chimneys or ventilation outlets that could expel any contaminants onto the surface to be treated. Neutralize their effects during the work.
/!\ Professionals – large surfaces
To ensure compliance with the prescribed thicknesses and the warranty of future performance of RD-Elastometal, it is necessary to measure the thickness of the existing coating before starting the work and compare it with the results after application.
Inspection of bolts/fasteners
Inspect the condition of the bolts fastening the steel sheets together. Defective fasteners and bolts must be repaired or replaced.
/!\ Tip
Applying a coat of RD-Elastometal with a brush on each fixing after inspection allows for visualizing the progress of the inspection and adds a first protective layer to these weak points. This step is recommended in harsh environments or on heavily corroded surfaces.
Edges and Corners
Check the edges and corners. These areas are more prone to corrosion. In case of corrosion or delamination (bare metal), apply RD-Elastometal with a brush.
Non-ferrous Metals
Products to use as a primer if you need to paint:
- New galvanized steel or stainless steel: RD-Monoguard.
- Galvanized steel exposed for more than one year: RD-Elastometal.
- Aluminum: RD-Elastometal diluted by 25% with water.
Using RD-Roof Fleece Reinforcement
In case of a roof with waterproofing issues, it is necessary to use the RD-Roof Fleece reinforcement on the overlaps between each panel and on the various elements that may be fixed to the roof: chimneys, skylights, roof windows, etc.
The fleece should be applied in the direction of the slope on each overlap. It is possible to do this only locally if the source of the leaks can be accurately determined.
Other areas may also require the use of the fleece:
- Horizontal overlaps if they are deformed and exposed to weather
- Heavily rusted areas
- Areas where water might stagnate
- Connections to walls
Areas Subject to Persistent Contamination
Surfaces near chimneys or ventilation outlets are sometimes subjected to contaminated airflows or steams, which, depending on their nature, can attack the coating and accelerate its deterioration.
It is recommended to apply one or two coats of RD-Hydrograff HP Clear as a finish on RD-Elastometal in these areas. RD-Hydrograff HP Clear is a two-component water-based polyurethane varnish that is highly resistant to abrasion and chemical contamination.
Application of the products
Application of the waterproofing coating
RD-Elastometal After completing the preparatory work, the application of RD-Elastometal generally begins at the edges of the roof. For safety reasons, this can be done with a roller.
Then apply RD-Elastometal over the entire surface starting along the ridge (highest point). Begin from one edge and move following a trajectory perpendicular to the slope of the roof. Then, progressively work your way down.
Airless application of RD-Elastometal generally allows the work to be completed in just two passes/coats with better control of the applied thickness.
If it is hot or windy, it is advisable to work in such a way that the overspray does not blow back into the fresh paint. This will result in a more aesthetic and smooth finish.
If the application is done with a roller, a third coat or more may be necessary to achieve the specified thickness.
Allow the coating to dry for +/- 6 hours before applying the next coat. This duration may vary depending on climatic conditions.
Treat areas that may be subject to persistent contamination (see above) with RD-Hydrograff HP.
When the work is finished, and to inspect the application without damaging the coating, it is important to wear shoes with rubber soles and walk carefully.
Application Equipment and Product Specifications
RD-Elastometal
Brush or roller: 14 mm polyamide or 3/8" bristles.
Airless device: minimum pressure 180 bar / 2600 psi. Nozzle opening: 0.017 - 0.023 in.
/!\ Airless application is strongly recommended for panels with very pronounced ribs. This facilitates the application of a coat with a more consistent thickness on all sides.
Ready-to-use product. Stir mechanically for a few minutes before application. Dilute up to a maximum of 3% with water for airless use in hot weather (> 25°C / > 77°F). Never dilute more to avoid reducing its anticorrosive and waterproof properties.
Drying time: (20°C – 68°F)
Touch dry: +/- 3 hours
Recoatable: +/- 6 hours
RD-Roof Fleece
Available in rolls of 100m x 20cm wide. RD-Roof Fleece can be cut to the desired length with scissors and placed over the overlap of the panels in the direction of the slope. It is adhered by applying a layer of RD-Elastometal with a brush through it.
This operation should be repeated on all overlaps or those posing a problem.
RD-Eco PowerClean
Low-pressure nap sprayer. Dilute between 5 and 20% in water depending on the degree of soiling.
Spray and let to react for 15 minutes.
Then rinse with a high-pressure cleaner. Tool cleaning Clean with clean water only.