Home Applying Solar-Reflective Cool Roof Coatings: Complete Guide for Bitumen, EPDM & Metal Roofs.
This solution explains how to create a Cool Roof by applying a high-albedo coating, designed to reflect a maximum amount of solar rays and increase the roof's thermal emissivity. This helps to reduce heat buildup inside the building, thereby improving its energy efficiency and comfort.
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Products presented
RD-Elastodeck 
Single-component liquid waterproofing coating for roofs, decks, and balconies.
From €15.62 / Kg View
Single-component liquid waterproofing coating for roofs, decks, and balconies.
RD-Sunguard 
High performance solar and heat reflective Cool Roof coating with exceptional properties.
From €63.51 / L View
High performance solar and heat reflective Cool Roof coating with exceptional properties.
RD-Eco Powerclean 
Powerful biodegradable alkaline concentrate composed of anti-flash rust additives for cleaning...
From €17.08 / L View
Powerful biodegradable alkaline concentrate composed of anti-flash rust additives for cleaning...
The problem
Bituminous roofing is generally very dark, even black, while metal panels roofs can also have a dark color. In summer or during periods of strong sunlight, these dark colors absorb solar rays and accumulate a large amount of heat, which, depending on the building's insulation, can migrate inside.
The effects vary according to the level of insulation, but generally, this results in an increase in electricity consumption to cool buildings equipped with air conditioning, or in suffocating and persistent heat in other cases.
Not all paint systems are suitable for roof application! Adhesion and elasticity of the coating are essential to accommodate movements caused by temperature variations. And of course, resistance to standing water, weather conditions, UV, etc., is critical.
For a bituminous roof, it is crucial to use a coating that effectively insulates and prevents the rise of bituminous substances. Under the effect of heat, these substances can seep through the paint film, causing brown stains. This is not desirable on a white roof.
Roofing made of EPDM is also more challenging to cover.
With over 25 years of experience in roof coating systems, RD Coatings offers an innovative solution.
The solution
RD-Sunguard
RD-Sunguard is a new-generation solar-reflective coating combining very high reflective properties, excellent resistance to soiling, and outstanding retention of its white color over time. These are crucial properties for creating a cool roof that have been tested in laboratories according to ASTM E1980-11, ASTM E903, and ASTM C1371 standards, both before and after exposure!
This water-based, single-component coating is extremely easy and quick to apply as a topcoat over RD Coatings’ roofing paints. It makes this system accessible for commercial and industrial buildings as well as residential homes.
An effective technique to enhance the performance of photovoltaic panels!
Several studies show that lowering the temperature on the surface of a roof equipped with photovoltaic panels can help optimize their performance.
System(s)
The systems described below are intended for roofs in good condition. In case of waterproofing issues, ponding water or corrosion, it is recommended to refer to the specific solutions for these situations or contact RD Coatings for personalized advice.
* Bituminous roofing in good condition, installed for at least 1 year
| Product | Consumption | Dry film | |||
| 1st layer | RD-Elastodeck White | 1 kg/m² 50 s/f-g | 450 µ 18 mils | ||
| 2nd layer | RD-Sunguard | 0,10 l/m² 440 s/f-g | 40 µ 1.6 mils | ||
* Steel sheets in good condition, installed for at least 1 year
| Product | Consumption | Dry film | |||
| 1st layer | RD-Elastometal White | 0,4 kg/m² 130 s/f-g | 175 µ 7 mils | ||
| 2nd layer | RD-Sunguard | 0,10 l/m² 440 s/f-g | 40 µ 1.6 mils | ||
* EPDM membranes
| Product | Consumption | Dry film | |||
| 1st layer | RD-Elastodeck White diluted with 5% water | 0,2 kg/m² 250 s/f-g | 90 µ 3.6 mils | ||
| 2nd layer | RD-Elastodeck White | 0,8 kg/m² 60 s/f-g | 360 µ 14.4 mils | ||
| 3rd layer | RD-Sunguard | 0,10 l/m² 440 s/f-g | 40 µ 1.6 mils | ||
Even though RD-Sunguard has excellent coverage, it is recommended to use a white shade for the initial layers to achieve maximum solar reflection.
Application conditions and work preparation
Environmental conditions (general requirements):
• Minimum air and substrate temperatures: 10°C / 50°F for 24 hours.
• Maximum surface temperature: 55°C / 130°F.
• Maximum relative humidity: 80%.
• Surface temperature must be at least 3°C / 5°F above dew point.
• No threat of rain for 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-Elastodeck & RD-Elastometal do not have an overcoating window constraint. In other words, in case of a work interruption, for example due to a sudden change in weather conditions, the work can be resumed without difficulty once the surface is cleaned.
Preparation of the work:
Steps:
1. Check the drains, clean them, and remove any obstructions. Repair if necessary.
2. Remove moss and lichen down to the roots with a suitable biocide or bleach (be careful of stains).
3. Degrease and clean the surface with RD-Eco PowerClean, a powerful biodegradable degreaser, or a good detergent.
4. Rinse and clean the surface using a high-pressure cleaner at 120 bars / 1700 psi equipped with a rotating nozzle with a zero-degree angle. This method will remove impurities and other non-adherent elements from the surface.
Make sure the surface is clean, dry, degreased, and free of any contaminants before applying the paint.
Some important points
Presence of an existing coating
Remove parts that no longer adhere. Never paint over a coating that adheres poorly! If there are blisters, pierce and cut them, then remove the non-adherent coating.
/!\ Standing Water
Particular attention must be paid when working on roofs with insufficient slope, as there is a risk of standing (ponding) water.
If water remains for several days after rainfall, it is essential to increase the thickness of the intermediate coat of RD-Elastodeck by an additional 450 to 900 µm dry - 18 to 36 mils dry, which corresponds to 1 to 2 kg/m² - 300 to 150 s/f-g more than the standard consumption.
It is also recommended to add the RD-Roof Fleece reinforcing fabric to ensure better resistance and long-term durability of the system.
The installation of this fleece is explained in our solution: “How to renovate a leaking flat roof?”
🔧 Note: Standing water is often caused by lack of maintenance of gutters or the roof in general. Blockages (leaves, debris...) frequently obstruct proper drainage. Regular cleaning may be enough to solve the issue.
Chimneys
Check the nature of the fumes; if they are aggressive, a layer of RD-Hydrograff HP should be applied around the chimneys over a few meters to increase chemical resistance.
HVAC Ventilation Units
There is often standing water near ventilation units. Redirect the flow during application.
Product Application
The products are ready to use. Stir mechanically for a few minutes just before application.
The products should be applied in the order indicated in the system tables above.
Airless spraying is recommended for large surfaces as it allows the recommended thicknesses to be reached more quickly and with fewer coats.
Application with a roller is also possible and sometimes recommended in windy conditions.
In the case of applying thick layers of RD-Elastodeck or RD-Elastometal with a roller, one or two additional coats may be needed to reach the prescribed thickness.
Application material
RD-Elastodeck
Brush, roller or airless (nozzle size: 015–023)
Application by airless is recommended and makes it easier to reach the recommended thicknesses. Use a device that allows a minimum pressure of 180 bar / 2600 psi at the outlet.
RD-Elastometal
Brush or roller.
Airless device: minimum pressure 180 bar / 2600 psi. Nozzle opening: 0.015 - 0.023 in.
RD-Sunguard
Brush, roller or airless (nozzle size: 010–012)
RD-Eco Powerclean
Low-pressure sprayer. Allow to work, then rinse.
Tool cleaning
Clean with clean water only.
Product application
RD-Elastodeck
Product is ready-for-use. Otherwise dilute with water on porous or smooth surfaces or when applying in warm weather conditions (> 25°C / > 77°F).
Drying time: (20°C - 68°F)
Touch dry: +/- 3 hours
Recoatable: +/- 6 hours depending on the thickness.
RD-Elastometal
Ready-to-use product. Stir mechanically a few minutes before application. Do not dilute.
Drying time: (20°C - 68°F)
Touch-dry: +/- 3 hours
Recoatable: +/- 6 hours
RD-Sunguard
Product is ready-for-use. Dilute with maximum 3% water when applying by airless or in warm weather conditions (> 25°C / > 77°F).
Drying time: (20°C - 68°F)
Touch dry : +/- 30 minutes
Dust free : +/- 45 minutes
Dry : +/- 1 hour
RD-Eco Powerclean
Dilute between 5 and 20% in water, depending on degree of soiling. Spray on and leave for 15 minutes. Then rinse with a high-pressure cleaner.