Top 5 Best Cold Liquid Applied Waterproofing Systems

Cold Liquid Applied Waterproofing Systems

Compared to other flat and pitched roofing systems, cold liquid applied roof waterproofing systems offer a unique and diverse option. Early systems have been used from as far back as 1800. As more sophisticated technology allows the mixing of new formulas; new and improved systems are becoming more readily available at increasingly cost-effective prices.

In this article, we will take an in-depth look at five of the best types of cold liquid applied waterproofing membranes available on the market today, and the best application for their specific formulas.

Knowing which system to use is not always easy. This will shed some light on which liquid waterproofing membranes are best for different specifications and roof substrates. We will also list some waterproofing systems available in each category and the specific benefits of these systems.

Whether your buying criteria are for certification, speed of application, cure time, or cost; liquid waterproofing has something to offer everyone. If you’re interested, read on to find out more.

Polymethyl Methacrylate (PMMA)

PMMA’s were first developed in Germany in the first half of the 1900s and were brought to the market only a few years later. PMMAs have rapid curing qualities, they are very flexible yet extremely tough and robust. This has made it a very successful product for many applications in the construction industry.

PMMA is typically a two-component system, comprising resin and catalyst. The use of the catalyst or hardener in this system causes a chemical reaction creating heat which cures the product at a rapid rate, even at temperatures down to 0oC or lower.

Roofing contractors will mix the two components on-site and apply the complete system immediately, ensuring they have enough time to evenly lay the product to its correct specification before it is cured.  

PMMA’s are ideal for roof waterproofing projects where access is restricted and there are time restraints. Because it is a flexible, durable, hard-wearing, and rapid curing roof waterproofing system.

By far the most effective PMMA waterproofing system on the market in our opinion is RapidRoof Pro. A high-performance, rapid curing, cold liquid applied flat roof waterproofing system with a typical curing time of 20 minutes. This system has been rigorously tested, has over 200% elasticity, and will cure down to 0oC making it suitable for year-round application.

Polyurethane (PU)

One of the most popular and widely used cold liquid applied waterproofing systems on the market today are polyurethanes, or PU’s as they are often abbreviated. PUs are some of the most versatile systems as they are used for a multitude of applications including roofs, gutters, and walkways. Due to their durability, they are very suitable and are often used for high foot traffic areas – further cementing their versatility.

Typically, a two-part system contains a double waterproofing layer and a glass fibre reinforcement matting. PU’s have become the preferred choice compared to some other liquid-applied waterproofing systems.

The most versatile and effective polyurethane we believe to be on the market is Liquid Roofing Systems’ FastCoat Pro. This is a single component, fully reinforced, pure polyurethane system that offers an exceptional long-term solution to flat roof waterproofing. FastCoat Pro also offers an additional traffic coating for use on balconies and walkways.

Unlike many alternatives, FastCoat Pro can offer substantial reductions in application time. This helps to save significant amounts of project costs and reduces disruption.


Rubber polymers have seen many advancements since their development more than 50 years ago. SEBS polymer waterproofing systems are used in the development and refurbishment of both metal and asbestos flat and pitched roofs.

Once applied, this system produces an elastomeric roof coating that is long-lasting and excellent protection against water ponding and ingress. Due to its excellent water-resistant properties, it is often specified for flat roofs and roofs that have a lot of standing water.

Its elasticity allows the system to cope with the expansion and contraction that occurs in typical roof movement and makes it a very suitable waterproofing solution for large-scale industrial or commercial roofs.

Many rubber polymer systems are single component and self-priming making them ideal for large-scale projects that are time-sensitive.

The most effective and versatile SEBS waterproofing system on the market in our opinion is Karnak’s Elasto-Kote. It is a thermoplastic system specifically designed to be applied onto flat and pitched industrial roofs. It offers an exceptionally high-performing elastomeric system with a built-in rust inhibitor, 85% solar reflection, and 650% elongation.

Cold Liquid Applied Bitumen

Since the early 1800s, bitumen has been used as a waterproofing solution where natural bitumen was mixed with other natural materials and fibres. Modern technology has come in leaps and bounds since its first use. Since then, bitumen roofing systems have become one of the most diverse and widely used systems on the market today. Thermal expansion in materials has contributed to the considerable popularity of these systems, compared to other construction materials such as concrete or steel.

Bitumen roofing systems come in many forms on today’s market, such as felt, asphalt, and rubberised bitumen. The latter, cold liquid applied bitumen is the type of system we will be looking at in more detail in this section of the article. Whether you need a full roof coating system, underground tanking, or a simple roof leak repair product; hopefully here we will have an answer to your problem.

LiquidRubber is LRS’ highly advanced eco-friendly polymer. It comes in two forms as it can be used both as a hand roll-applied system, but possibly more interestingly; LiquidRubber Instant Set is a spray-applied system used to coat large scale industrial roofs in a fraction of the time.

LiquiTank is a variation of the LiquidRubber system. A high-performing waterproofing membrane designed specifically for tanking, structural and underground waterproofing.

Repair Systems

Most chemical compositions and formulas also have repair systems in their range. Each of these is suitable to repair different size and severity of roof damage. We think it best to add a section for roof repair systems. Here we can determine which are most suitable for different repair needs.

Typical roof repair jobs vary from patch repairs, crack repairs, part, and full encapsulations. Depending on if there is a leak, standing water on the roof, or the roof substrate that needs repairing; certain repair systems will work better.

For example, Karnak 19 Ultra is an extremely impressive repair system. It describes itself as the next generation of bituminous elastomeric flashing cement. 19-Ultra is ideal for use on roofs that have a lot of water as not only will it create an instant watertight seal, but it can also actually be applied underwater.

RapidRepair is a PMMA-based repair system that contains premixed glass fibres, which increase its strength and flexibility. providing greater strength and bridging properties, allowing the faster and more effective application to acute areas of damage requiring repair. This repair system is ideal for repairing cracks or split surfaces on flat, dry roofs.

Karna-Flex is an elastomeric, thermoplastic rubber sealant formulated to be used on properly prepared metal, concrete, spray polyurethane foam, and plywood roof substrates. Its ease of application, superior adhesion, elasticity, and durability make Karna-Flex an ideal repair sealant. Available in a brush mastic or caulking cartridge.

How to Know What to Specify?

There are cold liquid applied waterproofing systems for almost every roofing application. Hopefully, above you will have found the answer to your questions.

Still Not Sure What to Use?

There are cold liquid applied waterproofing systems for almost every roofing application. Hopefully, above you will have found the answer to your questions.

For more information on any of our waterproofing products or systems, call on 01948 841879 or email the specialists today.