Michael Jones, National waterproofing manager at Peter Cox outlines a range of waterproofing materials in construction, and the benefits they can bring if used correctly
Last month, the UK saw a range of weather across the country – from a maximum temperature of 17.2 °C to a minimum of -8.1 °C, alongside 86.6mm of rainfall in 24 hours in certain areas. With extreme weather events, such as flooding, becoming more frequent, waterproofing materials in construction has never been more important.
As one of the most important facets of a building, waterproofing can help to improve the durability of a variety of surfaces. Whilst there is a range of waterproofing materials available, not all materials are suitable for every purpose.
It is therefore crucial that construction professionals know which materials are right for each individual job, as without the correct ones a building project can run into major problems.
Waterproofing for walls and floors
When choosing a waterproofing material for walls and floors, the material should offer more than just protection against water. It should also act as a barrier or be permeable to air and vapour, to prevent moisture from being trapped under any insulation or within masonry and carpentry. If it is not able to do this, it can result in mildew, mould or fungi. Here are three key materials that can provide this level of protection:
1. Cementitious coating – Type A waterproofing
This coating usually consists of sand, organic and inorganic chemicals, alongside waterproof/crystalline substances. The active ingredients are combined with lime, which starts a hydration reaction that results in a waterproof seal. This material can be used alongside watertight concrete or Polypropylene membranes, which work to lock structures down and manage groundwater ingress.
Cementitious coating is used for a wide range of applications, including treating water-retaining structures, like tanks and concrete tunnels. It is typically easy to work with and – if applied properly – it can provide a durable watertight seal that can last for many years. The product is also available in a spray format, which is useful for larger surfaces.
However, despite being easy to apply, it can lack flexibility as concrete can only minimally flex and stretch. You should also keep in mind that it should not be punctured.
2. Watertight concrete – Type B waterproofing
This relies on a new structure being constructed using watertight concrete with the addition of additives within the concrete. For the purposes of providing an integral waterproofing system, the concrete must be in accordance with BS EN 1992 Eurocode 2 and the waterproofing admixture should be compliant with BS EN 934, and in accordance with both Table 1 and Section 9 of BS 8102:2009.
This material can be cost effective, as concrete is typically specified in the construction of new retained structures, it enables you to use the structure itself as part of the waterproofing design.
Although, it does require careful construction to avoid honeycombing in the concrete, which can occur through a lack of compaction and cold – or contamination of – construction joints as a result of thermal contraction and shrinkage.
3. Polypropylene membrane – Type C waterproofing
Also known as a Cavity Drain Membrane, this option is an addition or alternative to the two above materials when waterproofing structures. When fixed to the walls and floors, an impermeable high-density Polypropylene membrane with an 8mm stud height to walls and a 20mm stud height to floors, forms a cavity.
Whereas traditional tanking holds back water and pressure, a Cavity Drainage Membrane acts as a drained waterproofing system. It’s designed to allow moisture in, enabling it to depressurise, and then to be sent to a drainage point via hidden drainage channels.
This option is widely considered as the failsafe approach, providing it is designed correctly. It does not impose any load onto walls and can be easy to install to concrete walls, brickwork, or blockwork. Once installed, a professional should check the system at least every six to twelve months.
You must also take great care when the system is designed, installed and sealed – it does require skill to ensure it is properly working so that moisture, smells and dampness are not able to penetrate into a room.
Waterproofing for roofs, balconies and terraces
As an area of a building that is susceptible to water infiltration, ensuring a roof is waterproof is key.
Often the materials used to construct a roof are already waterproof, but given the area can undergo intense inclement weather, it is important to add extra waterproofing measures. Waterproofing materials used on balconies and terraces must also be resistant to UV rays and be flexible, as the areas experience movement due to changes in temperature.
The following materials can be used for roofs, balconies and terraces:
1. PVC waterproofing membrane
This is a popular product for roofs as it is water and vapour-permeable, so it can let moisture out of the roof space of a building.
It is easy to install and can be reinforced to offer extra durability. With a unique product formula, it can have a long lifespan ranging from 30 to 50 years.
2. EPDM rubber
EPDM rubber is available in membranes with a thickness of ideally 2mm to 6mm. Its flexibility and ability to expand and contract with temperature changes mean it is a good choice for roof waterproofing.
The material can also be formulated to be resistant to temperatures as high as 150 degrees celsius.
3. Rubberised asphalt
Rubberised asphalt can provide great protection against a wide range of weather conditions, as it is very tough and flexible. It also dries within three to four hours after application.
4. Bituminous membrane
This is recommended for commercial and residential properties as it is an easy to apply material. It has a strong endurance and is made from a mix of organic liquids.
Despite these qualities, as it is made from crude oil it is not the most eco-friendly waterproofing material on the market. It can also have a low shelf life as the adhesion properties decrease over time.
Whilst there are a multitude of domestic and commercial options for structural waterproofing that can help to provide buildings with extra protection, choosing the best material for your space and budget requires careful planning.
Every construction professional should carry out their research before deciding on a material, taking into consideration a building’s purpose and a client’s need.
Michael Jones
National waterproofing manager
Peter Cox
Twitter:@petercox1951
LinkedIn: Peter Cox Property Services
