The proof is in the pudding when it comes to choosing

Waterproofing solutions for refurbishments

Driven by the need to maximise their assets, building owners are looking to exploit their building’s footprint by refurbishing subterranean areas for new uses, however it’s more complex than it may seem. With 75 per cent of all building failures being attributed to water ingress, and 95 per cent of basements suffering from the problem in some form, it is vital to get waterproofing right. Whether the project in question is commercial, industrial or residential, the correct specification of below-ground waterproofing products is critical in order to protect buildings.

That specification needs to include a thoughtful approach to identifying the correct product for the job, and refurbishments differ greatly from new builds when it comes to options for below ground waterproofing. New build projects generally enable waterproofing systems to be designed and installed together with the concrete basement structure. This means that membrane systems can be used, applied either externally or internally to provide varying degrees of protection to the structure, and another option is watertight concrete, which also offers a very high degree of protection.

Such options are not normally open to specifiers in refurbishments, however, due to the difficulty of installing such systems in completed buildings, and this is particularly the case with externally applied membranes. Refurbishments pose other challenges, with older buildings perhaps not having had waterproofing installed during construction, and requiring a sensitive installation to a complex existing building fabric with minimum disruption. The various technical challenges presented mean that seeking specialist advice early in the design process is essential to achieving the right specification.

Sika provides the full range of waterproofing options to specifiers, whether it’s for a new build or a refurbishment. So in addition to externally-applied membrane systems and watertight concrete, the company can offer a wide range of solutions for refurbishment schemes. These include the highly effective render systems and cavity drain water management systems, which provides flexibility where sites do not allow for tanking methods.

A long-established solution which has seen success in a wide range of refurbishment projects, the Sika 1 Pre-bagged Waterproofing System is a versatile cementitious render, the core of which has been successfully used for 100 years as a tanking method. Its continued relevance was demonstrated recently on a complex and challenging high end refurbishment of basement areas at the Lancasters, a Georgian terrace in west London. With some areas requiring waterproofing to the highest level, a careful and diligent approach was needed.

Sika 1 (so named because it was the first Sika product), is a liquid waterproofing admixture that is mixed with a blend of kiln dried specially graded aggregates and cements. This render provides a highly effective method of preventing water ingress. Once applied to walls and floors, the render bonds monolithically to the prepared substrate, and the admixture reacts to any water present, turning into a jelly-like substance which blocks all gaps and capillaries.

This provides an invisible as well as impregnable seal, which is so effective that it was also used to keep water in basement swimming pools at the Lancasters.

Where site conditions or design criteria in a refurbishment project do not allow for internal waterproofing using traditional tanking methods, a suitable solution is a cavity drain system.

The product lines the inside of the structure, managing any water that penetrates the substrate by directing it to a drainage and sump system to be discharged away from the building. While providing an effective waterproof barrier, water management systems do involve long term maintenance and associated running costs.

Sika produces a full range of concrete repair mortar products, which range from pure cement-based options to cementitious, polymer-modified products and epoxy-based materials for different requirements. These are all compatible with Sika waterproofing systems and there is the option of special mix-in- the-bag packs for onsite convenience. The company also produces a range of high performance concrete crack repair products.

The 2009 revision of BS8102 states that a waterproofing specialist should be included as part of any design team so that an integrated waterproofing solution is created. This reflects the complex nature of many below ground waterproofing schemes, and the critical need to protect buildings against water ingress as increasing numbers of specifiers want to refurbish existing buildings to exploit underground space.

Sika is committed to providing proven and economical solutions to provide water tightness for even the most challenging projects. It is the only manufacturer that is able to offer the complete range of waterproofing solutions to specifiers – covering waterproof mortars, bituminous coatings and watertight concrete in addition to membranes, render and cavity drain options. This, combined with the expert advice and support the company is able to provide, means customers can have the confidence they will find the right product for the job.