How to restore a flat roof covered with a bituminous roofing?

RD-Elastodeck, an elastomeric coating, safe and easy to apply, designed to waterproof most flat surfaces.

The products that you need

Restore a flat roof on video


Préparation de la surface


The problem

Many flat roofs around the world are originally protected with bitumen-based membranes, often referred to as roofing. An efficient and inexpensive method of covering warehouses, factories, houses, etc.

They are subjecte to extreme conditions and many stresses due to their permanent exposure to outdoor weather conditions. The membranes expand and contract continuously under the influence of heat and cold; they must not only resist rain but also hail, snow, sunlight, erosion, etc. The conditions are terrible, no matter where you are in the world!

Due to the continuous movement of the construction and the weather, the membrane eventually no longer adheres to the surface and tears, allowing water to pass through. This is the start of many problems: leaks and other damages.

The consequences of doing nothing are costly: stocks and production tools are damaged, furniture damaged, certain areas can no longer be occupied, interrupting production and potentially causing significant economic losses, mold, etc.

Sooner or later, renovations will have to be done.

In the case of complex industrial roofs with many connections or areas that are difficult to access, repairing and waterproofing only the specific areas where you think the leak might be coming from is not an effective solution as water can come from much further away than you may think!

The flexibility and elasticity of some competitive products to cover an old roofing may not be sufficient and there is a real risk of water leaking very soon after the repairs, especially at the fittings. Finally, removing an old bituminous membrane and installing a new one is tedious and expensive.

RD-Elastodeck is a very effective solution which will solve the majority of the problems and will durably protect the roof!

The solution


RD-Elastodeck is an excellent solution for the renovation of these roofs. A safe and easy-to-apply, one-component water-based coating that will reduce the risk of further leaks in the future.

Applied to a roof, you obtain an elastic protective membrane similar in appearance to rubber, which will solve the problems of water infiltration.

Its estimated service life is over 15 years !

Thanks to its great flexibility and permanent elasticity, RD-Elastodeck permanently adheres to the surface and follows the expansion movements of the roof. The new membrane will be durable and highly resistant to different weather conditions including UV rays, rain, hail, snow, hot, cold, etc.

The system is used successfully in regions such as North America, Europe, Mediterranean and Scandinavian countries and South East Asia.

It should be noted that RD-Elastodeck is lightweight. After the coating has been applied and once it is dry, the additional weight on the roof is only about 1.3 to 3 kg per m².

RD-Elastodeck 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. They are easier, faster and very reliable solutions that do not compromise on quality in any way!

The products being 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 and the applicator by using products that are more respectful of the environment.

Benefits and expected performance of the system

The service life of the system is generally over 15 years! And a majority of projects can benefit from the RD Coatings warranty.

These are the main advantages of RD-Elastodeck for the renovation of flat roofs:

For the project manager/owner

  • Economical solution
  • Highly efficient and durable system
  • Solution with a guarantee
  • Eco-friendly
  • Water based, safe, no fire hazard when applying
  • Virtually no odor, can be used on occupied buildings without disturbing occupants
  • Wide choice of colors

For the applicator

  • SCS solution
  • One-component product
  • Easy application
  • Low VOC, close to zero
  • Unlimited coating window
  • No pot life
  • No isocyanates
  • Dry fall, almost no overspray
  • Quick application

Prepare the job


As with any outdoor project, try to avoid starting a job in rainy weather. A minimum of 10 ° C / 50 ° F and no rain expected during and immediately after application are required to apply products comfortably.From 15 ° C / 59 ° F, working conditions are comfortable and allow higher productivity.

If the project is located in a very hot area with very intense sunshine during application, you should avoid applying the system when the sun is most intense and prefer working early in the morning or late afternoon.

If you are working in humid climates, and especially if it is cold after sunset such as in the fall or spring, be sure to finish the job a few hours before dark. Otherwise, you risk having condensation covering the fresh paint and preventing it from drying. If you are working at dawn, beware of condensation on the surface, avoid it!


Avoid carrying out waterproofing work in autumn, winter or spring when the weather conditions are sometimes too uncertain. RD-Elastodeck does not have a cover window. In other words, if the work should be interrupted due to a sudden change in the weather, it can be resumed later without any problem!

Surface preparation

The surface must always be clean, dry, degreased and free of any contaminant.

The most popular and fastest way to do this is to clean the surface using a pressure washer powered at 220 bar / 3200 psi and equipped with a rotating nozzle with a zero degree angle. This method will remove dirt, possible loose paint and other loose elements from the surface.

Any remaining oils or fats should be removed with soap.

Moss and mildew can be removed with suitable cleaners. Consider using biodegradable solutions that are easy to find and very effective.

If there is a coating still present, check if it is still adhering properly, if not remove it. In general, when existing paint resists high pressure cleaning, it usually has sufficient adhesion and can stay in place. At the end, rinse and brush with clean water.

The surface must be completely dry before applying the waterproofing system.

Edges and ledges

Also check the edges and connections with walls, chimneys or any other equipment that can be found on a roof. These are places subject to water infiltration faster than flat surfaces.

RD-Elastodeck can be used on most types of mineral surfaces and is easy to use with the backing mesh to seal these more fragile areas.


It is preferable to apply RD-Elastodeck with a roller or with an airless device. You can also brush it on hard to reach areas. If spraying is not possible, such as in windy weather, you can apply the paint with a roller. It will just take a little longer and you will need to apply more coats to achieve the minimum thickness requested, but it is still a simple and reliable option.

The type of brush to use is very common. If you are spraying, use an airless with a minimum power of 180 bar or 2600 psi and a nozzle varying between 0.017 and 0.023 inches.

If you are using a roller, we recommend using 14mm / ½ inch polyamide rollers.

The application

Preparation of the RD-Elastodeck

RD-Elastodeck is ready to use, stir it mechanically for several minutes and optionally dilute up to 3-5% with water if working in very hot weather to slightly delay drying.

Installation of the reinforcement mesh

Start with the specific areas: edges of chimneys, ventilation, walls, drains, etc ... before tackling the flat surface as these are sensitive areas that deserve a lot of attention. The use of the 20 cm wide RD-Roof Fleece is generally recommended for its ease of handling.

Cut and apply the mesh half on the roof and half on the object so that there is a minimum of 10 cm / 4 inches of mesh on each surface. Then apply a brush coat of RD-Elastodeck above and through so that the coating comes into contact with the surface.

The second step is to lay down the RD-Roof Fleece reinforcement mesh to the flat surface of the roof. Use the 120cm / 47inch wide RD-Roof Fleece and cut it to the appropriate length. RD-Roof Fleece is available in different widths and can be cut to size depending on the situation. This mesh is perforated and very resistant. You would need tremendous pulling force to tear it apart. The quality of the mesh is very important.

Unroll RD-Roof Fleece on the flat roof surface and distribute it evenly. The connections between each mesh must have an overlap of at least 5 cm or 2 inches. Then apply with a roller or brush a first coat of RD-Elastodeck.

Let dry 4 to 6 hours before applying the second coat.

This first step takes the most time since you are handling the mesh and the paint at the same time.

The application

After the application of RD-Elastodeck with RD-Roof Fleece, the application of the second coat will generally be carried out with an airless device. It allows rapid application of a thick film with a uniform surface and without traces of rework. RD-Elastodeck does not cause much overspray. In addition, it is dry fall!

If you decide to apply the second coat by roller, you will usually apply more coats to achieve the prescribed thickness. The application of successive layers of RD-Elastodeck avoids having pinholes.

Remember to measure the wet thickness during application, this will help you determine the future film thickness when it is dry. The final thickness is important and must be in accordance with our recommendations as it will be your guarantee for the long term performance of the RD-Elastodeck waterproofing system. It's the total amount of material applied that counts, not the number of coats as long as you have a minimum of two.

A good advice on the color

RD-Elastodeck is available in a wide variety of colors. Since it has excellent coverage, we recommend using a different color per coat. This will help you to perfectly distinguish one layer from another and be sure not to forget certain spots.

Finishing options

RD-Elastodeck is a waterproofing system that does not require any topcoat. But there are cases where it might prove useful or desirable like:

  • in case of regular traffic on the roof, consult our finishing products for RD-Hydrograff HP and RD-Monofloor PU floors
  • If you want to save energy with a special finishing coat reflecting infrared rays and reducing heat transfer inside the building, consult the RD-Roof White sheet (especially in hot countries with strong sunlight)
  • If there is a risk of chemical contamination from chimneys on the roof or nearby, use RD-Hydrograff HP Clear.

The roof is now protected against infiltration for many years.