All you need to know about Liquid Sealing Systems (LSS)

Today, there are a number of methods available to both private individuals and professionals to guarantee the watertightness of flat roofs. The democratization of this type of roof has led to a broadening of the solutions available to guarantee watertightness. Among the various methods of waterproofing flat roofs are Liquid Waterproofing Systems, or LWS. A SEL is applied to the entire surface of the roof in the form of a resin. Once applied, it forms a unified coating with attractive mechanical properties. However, it is also possible to complete the waterproofing by applying a cool roof coating to protect the roof from the heat of the sun's rays.

What is a Liquid Waterproofing System?

Liquid Waterproofing System is a solution used to protect surfaces. The product has been distributed in France since the 1960s. Over the years, the associated technical solutions have evolved.

SEL involves the application of a resin. Resins come in a variety of forms. Today, the most common are PMMA and polyurethane resins. PMMA resin is a recent arrival that is beginning to replace other resins, thanks to its more powerful technical properties. In fact, PMMA resin offers far greater resistance to temperature and weight, while also benefiting from shorter drying times. Polyurethane resin remains the most widely used, mainly because of its ease of use.

Depending on the location chosen, the characteristics of the resin vary widely. While Liquid Waterproofing Systems can be used in a wide variety of locations within buildings, on flat roofs they can also be used as a roof covering. In this case, it's imperative that the SEL is able to resist weathering, UV and water vapor.

When used for roofing, SEL is applied with a roller. There's no need to install special fittings. The Liquid Waterproofing System is applied like a paint over the entire roof surface. After applying several coats, the resin dries and the roof is then sealed by this uniform solution.

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What are the advantages of Liquid Waterproofing Systems?

In France, Liquid Waterproofing Systems account for only a small share of the roofing market. It is estimated that only 3% of flat roofs are covered with SEL. Despite this statistic, however, Liquid Waterproofing Systems are particularly effective, and offer a number of advantages.

Firstly, SEL is one of the only coatings that can withstand the continuous flow of people on the roof. Indeed, the difficulty in protecting flat roofs lies in finding systems that can withstand regular passage. If the roof is used on a daily basis, traffic can quickly damage most waterproofing solutions. Not so with SEL. These are categorized as resistant coatings.

What's more, SEL is very easy to apply, and a roller is all that's needed to apply this solution to the roof. Thanks to block-drying, management is simplified.

Last but not least, a Liquid Waterproofing System has good mechanical properties: durability, resistance to UV radiation...

How can I improve the performance of a SEL on my roof terrace?

Although SEL is an effective roof covering that resists ultraviolet rays, it does not protect against heat. Depending on where you live, this effect can quickly become even more pronounced. In large cities such as Paris or Lyon, the urban heat island effect is stronger than elsewhere. With dark roofs absorbing heat, summer periods can become stifling. However, the basic color of SEL resin is dark gray, which gives it a poor albedo and means that the material absorbs a lot of heat.

It is possible to improve the thermal performance of a Liquid Waterproofing System. This can be achieved by applying a reflective cool roof coating. Cool roof is a technical process that involves painting the roof surface with a white, heat-resistant paint. This paint, which has a very high albedo, reduces the surface temperature of the roof by reflecting the sun's rays back into the atmosphere. Inside the building, you can feel a difference of up to ten degrees less.

So, by combining a Liquid Waterproofing System and its excellent mechanical performance with the application of a cool roof reflective coating, it is possible to effectively protect buildings with flat roofs. These solutions can be used for both professional buildings and private homes.

To find out more :

• How much does waterproofing a flat roof cost?
  
• Waterproofing capabilities for steel roofs
• Is painting an EPDM membrane white a good idea?
  
• The co-ownership's responsibility for roof terrace maintenance
  
• What you need to know about reflective waterproofing
  
• Re-coating and alternatives for maintaining your waterproofing solution
• How to maintain a flat roof and what to do in the event of a leak