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Liquid waterproofing: overcoming the common application challenges

by Jennie Ward

Victoria Ramwell of Kemper System UK outlines the common challenges that should be covered during manufacturer training when it comes to liquid waterproofing application.

Victoria Ramwell, UK Marketing Manager at Kemper System UK.

When it comes to skills, it’s often the contractors who are expected to take sole responsibility of product application training. But it’s also vital that manufacturers of liquid roofing products step up to the plate to help raise standards.  

Even the most well-trained roofers need additional skills, especially when working with liquids. A client is far more likely to look at the smaller details than the larger areas, so contractors need the knowledge and training required to create these to the best of their ability. Applying a liquid product incorrectly is also incredibly expensive and time consuming to correct. 

There are also a lot of liquid systems on the market to choose from, with new products being introduced all the time. But it’s not a one size fits all process when it comes to the different liquid chemistries and application techniques. 

At Kemper System, quality system training is therefore a priority, which is why we’re delivering training to approximately 3,000 contractors a year across the entire group  – the UK and overseas – giving contractors the chance to become an approved applicator of our products. This includes contractor training at our headquarters in Warrington, Cheshire. 

There are a number of key areas which can often go wrong during liquid waterproofing application, and its vital that contractors undertake the specific training prior to installation.

Here are just a few examples of the common challenges which should be covered during manufacturer training: 

No matter how big or small the roof area, the success and long-term performance of liquid waterproofing relies on the bond between the material and the substrate. The importance of substrate preparation can’t be underestimated. Without the correct preparation, there is a chance that the liquid installation will fail prematurely. 

Liquid waterproofing can adhere to most surfaces, including existing single ply which requires refurbishment, bituminous sheet, asphalt, brick and stonework, metal and even glass. However, it will not bond to plastic (HDPE), silicone or wet substrates. 

It is vital that contractors ensure the substrate is clean, dry and stable prior to application. It must be free from any vegetation or moss, dust and dirt, and check there is no moisture in or underneath the substrate. There can’t be any ponding water or condensation on the roof, and it must be structurally sound and firmly fixed, with no voids or gaps of more than 2mm. 

Importance of priming 
Applying a primer helps the waterproofing coating to adhere to the substrate, and can highlight any deficiencies before the entire system is applied. Primers can also seal the pores on concrete substrates to prevent outgassing. 

It’s important to remember, however, there are different primers suitable for each liquid waterproofing system and substrate. Learning about the differing chemistries within the liquids and how they work with different primers is paramount. For example, some primers require mixing on site, are two components and have different over coating times. 

Contractors should be mindful to check the temperature of the substrate and the surroundings before applying the primer, being aware of the imminent weather forecast and potential falling temperatures – especially during winter working. 

Manufacturer training should go into detail about the required coverage rate of primers, and subsequent application of the liquid waterproofing to ensure a sound and durable solution overall. Primed areas must be waterproofed within seven days. 

Detailing on roofs
Roof systems typically fail because of insufficient waterproofing around details, outlets, penetrations, seams and laps. However, because liquid waterproofing is seamless, it’s often the preferred choice for many different applications. This includes roofs, walkways, terraces and car parks, as well as areas which require a lot of detailing as it reduces the risk of water ingress down the line. 

Manufacturer training should thoroughly cover the application process around outlets and penetrations, including rooflights, pipes and air conditioning units for example. Application of the waterproofing system around internal and external corners of a roof should also be covered in detail, as well as parapet walls. 

Stay ahead of the game
Don’t assume that all liquid waterproofing products are the same. Each one is different and so the manufacturer will have its own set of instructions and recommendations for effective application, including suitable substrates, surface preparation, mixing and application. 

Take advantage of manufacturers’ training courses to ensure you’re fully up to speed on the product to be used and how to apply it. When on the roof, don’t be tempted to cut corners; review and follow all the steps and advice listed by the manufacturer for all stages of installation. Kemper System training is part of the Basic Competency Programme (BCP), approved by the Construction Industry Training Board (CITB), and is available at its headquarters in Warrington. Strict Covid compliant measures are in place to ensure contractors and trainers are safe during the practical and theory-based sessions. The course covers all aspects of preparation, application and post-installation on all Kemper System solutions, as well as the most recent Building Regulations and health and safety requirements.


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