Waterproofing is the material used to prevent water infiltration into a structure. A waterproofing membrane refers to a continuous thin layer of material designed to prevent water moving across it. Waterproofing membranes often consist of waterproof plastic, rubber, or coated-fabric materials or liquid applied coatings that when properly installed provide waterproofing for the sub-surface.
Waterproofing is critical to maintain the integrity of concrete structures as water ingress into cracks in concrete foundations and walls, apart from eventually finding its way inside the building and causing damage, weakens the structure and leads to corrosion of steel elements inside the concrete, known as rebar, resulting in flaking and deterioration of the concrete surface often called concrete spalling.
Typically the material is applied over foundations of retaining walls, basements, carparks and balconies, and must be both flexible enough to conform to the shape it is covering and strong enough to resist tearing. Waterproofing membranes can also be used on concrete structures that are designed to hold water for example pits and tanks and are commonly used in wet areas laid between tiles and the concrete slab or substrate.
There two main types of waterproofing membrane; sheet membranes and liquid applied membranes. Each type of material and structure has its own specific requirements and determines the type of waterproofing membrane chosen and it’s application.
Sheet waterproofing membranes are thin material usually delivered in a roll which is laid over a surface. These include PVC, rubber-based, composite plastic or bitumen bonded with synthetic fabric. Some membranes have a peel-and-stick coating so adhesive does not need to be applied. Particular sheet membranes such as PVC sheet has the advantage that the sheet joints are weldable.
Cold-applied liquid membranes are spray-applied, brushed or rolled onto a surface and once cured provide an impermeable waterproof coating. These include polyurethane elastomers, cementious products, and other epoxy spray-applied membranes. Polyurea coatings are liquid spray-applied membranes that work on porous and non-porous substrates giving good crack coverage and a flexible impermeable finish when cured. Cementious products such as Vandex and Xypex are a polymer-modified cement product applied to concrete surfaces which can provide both waterproofing and concrete repair.
Torch-on membranes are usually a mixture of bitumen and plastic or rubber composites reinforced with polyester and are heated to fuse with the substrate and together to form a continuous membrane impervious to water which have a high-tensile strength and can withstand weather and traffic.
Each material has it own advantages and recommended usages depending on type of structural element to which it will be applied. Waterproofing services may be required for basements, slabs, retaining walls, wet areas and carparks and water holding structures such as tanks and pits. The most suitable type of waterproofing material will depend on both the structure and the position. It is essential to get expert advice from a waterproofing contractor to ensure the type of waterproofing is most suited to it’s application.