Applying EPDM Rubber Liquid in Four Easy Steps

When water gets into building, plant or vehicles the damage can be substantial and costly to repair. Unfortunately, it’s all too easy to overlook vital maintenance and repairs and let the effects of weather and aggressive substances damage valuable assets. 

Fortunately, by applying EPDM Rubber, your maintenance team or contractor can easily apply a durable, high-performance coating that will protect for years.

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To get the best from coating or sealing with EPDM, you must prepare surfaces thoroughly. Using the right techniques (we can advise you) is also essential. You’d do this if you were working with any rubber gaskets and sealants – for best results, please do the same with Liquid Rubber. 

Learn more today. Please call now on 0800 6120 750 or email us

Here are the four steps for applying EPDM Liquid Rubber correctly. When you’ve read this, we’re sure you’ll agree that EPDM Liquid Rubber deserves a place in your property or plant maintenance toolkit. With so much at stake, you’ll also understand why we’re so confident that our product, the world’s only true liquid EPDM rubber, is up to the job. 

STEP 1: How much Liquid Rubber do I need

Normal coverage when applying our EPDM rubber is 3.70 to 3.90 m2 (40-42 ft2) per 3.78 litres (1 US gallon) on a typical substrate. The required 0.5 mm (0.02 in.) film thickness is achieved when this spreading rate is used. Liquid Rubber covers up to 4.2 m2 (46 ft2) per 3.78 litres (1 US gallon) on an optimal surface. If you’re not sure how to calculate your material requirement, please contact us.

US Gallons Litres Coverage (m2) Coverage (ft2)
1/4 950ml 0.925–0.975 10–10.5
1 3.78 3.70–3.90 40–42
2 7.56 7.43–7.80 80–84
3 11.34 11.14–11.70 120–126
4 15.12 14.86–15.60 160–168
5 18.9 18.58–19.50 200–210
6 22.68 22.29–23.41 240–252

STEP 2: Preparing the surface

You can learn more about which surfaces are suitable for Liquid Rubber on our Suitable Surfaces page. 

As with all rubber sealants, preparation is vital to achieve a good finish. The surface to be coated should be clean, dry and structurally sound. You must also repair any gaps, holes or tears (you can rubber patch torn areas) and fasten loose areas with adhesive (contact cement) or pop rivets. Here’s a summary of preparation: 

  • Before applying EPDM rubber, remove any residual Silicone.
  • Wire brush any rusty or pitted metal to remove loose rust. Tightly adhering corrosion may be directly coated with Liquid Rubber.
  • Completely remove any residues of oil or wax with solvent.
  • Remove brittle caulk and loose portions of existing coatings with a scraper and/or a wire brush.
  • Remove as much as possible of asphalt-based aluminium coatings with a wire brush or abrasive disc.
  • Remove and replace roof cements with butyl caulk where necessary.
  • Remove chalk from white-rubber membrane by brushing with a detergent solution followed by a water rinse or working the surface with a stiff brush.

You can leave residual material that will give good adhesion when recoated. To improve the adhesion of the EPDM rubber, lightly sand the roof and any smooth metal or plastic fixings and surfaces you’ll be coating. On certain plastics, you may be able to use de-glossing solvent. 

STEP 3: Mixing Liquid Roof

IMPORTANT: Do NOT add the catalyst to the Liquid Rubber immediately. 

The container of EPDM Liquid Rubber is deliberately underfilled to allow for addition of the pre-measured catalyst that comes in your kit. You’ll need a drill and a mixer to incorporate the catalyst. For 950 ml (1 US quart) and 3.78 L (1 US gallon) cans, a short mixer will suffice. For 15.12 L (4 US gallon) and 18.90 L (5 US gallon) pails you MUST use a long-shaft mixer. 

First, mix the rubber material in the container. When it has gained a uniform consistency, centre the mixer shaft in the container and continue mixing until a vortex forms. Next, slowly pour all the catalyst into the vortex. Move the mixer up and down and in circles for 2–3 minutes until all material is thoroughly mixed. 

STEP 4: Applying EPDM rubber – it’s ‘liquid rubber paint’

Application of Liquid Roof is always better than applying several coats. You can apply Liquid Rubber at any temperature that allows it to be spread on the surface (with at least 12 °C/53.6 °F is for curing). 

You can also apply EPDM Liquid Rubber by brush, roller or squeegee. In fact, combining these application methods may be the most effective way to achieve a high-quality finish.

Around details such as edges, flashings and vents, we recommend that you paint on the Liquid Rubber with long, slow strokes. On flat surfaces or when covering very large areas, we suggest that you first pour a ‘serpentine bead’ of liquid EPDM. Next, distribute the liquid with a squeegee and finish applying it to the surface using a short-nap roller (we can recommend and supply suitable application tools). This will press out any air from cracks in the surface and even out the wet film. 

When applying EPDM rubber, the coating will self smooth once you’ve applied sufficient material. Depending on the ambient temperature, liquid EPDM remains workable for between four and six hours. As soon as the initial film has cured, you can apply any required touch ups or detailing. However, before doing this, we always recommend wiping the surface down with a suitable solvent – please ask us for details.

Temperature and cure conditions

Liquid EPDM cures with exposure to air. when applied, it is immediately waterproof and will withstand rain showers, pooling water or even freezing before it is fully cured. If water gathers on the surface before curing is finished, all that will happen is that the cure process will be paused until the surface is exposed to air again.

Between 12 and 26 °C (54 and 79 °F), the coating will be entirely cured within seven days. When applying EPDM rubber, curing isn’t affected by humidity. However, it is accelerated by sunlight and higher temperatures, and retarded by cooler conditions. Exposure to freezing before the end of the curing process won’t harm the film. 

No matter how long curing takes, the final properties and performance of your newly applied membrane will be the same. Unlike some widely-used materials, genuine Liquid Rubber roofing coating gives superb long-term protection – even when exposed to the most extreme conditions for many years. 

WARNING: Please read container for complete safety precautions and instructions. Heed all warnings. Please read all directions completely before beginning the application process. Please make sure all safety precautions are followed and appropriate safety equipment is used.

Still got questions? Need more information? Please call now on 0800 6120 750 or email us

 The information presented herein is furnished free of charge and is based on technical data that we believe to be reliable. It is intended for use by persons having technical skill and is at their own discretion and risk. Since conditions of use are outside our control we make no warranties, express or implied, and assume no liability in connection with any use of this information. Nothing herein is to be taken as a license to operate or a recommendation to infringe any patents.