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The what and where of waterproofing

Main image: TAL

A quick reference guide on the what and where of waterproofing.

Waterproofing is an important part in any build but with such a wide variety of products and systems available, it can be tricky to know which one to specify for a specific project. Walls and Roofs compiled a quick reference guide on the what and where of waterproofing.

Bitumen

Bitumen is a byproduct of crude oil. The quality of material and ease of production depends on the source and type of crude oil from which it is derived. Thanks to bitumen’s well-known waterproofing qualities, it is widely used in various forms.

It is available in three formats:

Advantage: High resistance to mechanical damage and punctures.

Advantage: Fully-bonded, seamless system with crack-bridging capability.

Advantage: No special equipment is required.

Note: Tiling over bituminous waterproofing systems can be problematic. Being thermoplastic in nature, bitumen in warm conditions tends to be viscoelastic (‘flow’ as a solid mass). In extreme cases this flow exceeds that achieved with deformable (flexible) adhesive and grout systems, and movement joints combined, resulting in “buckling” of the panel, cracking of tiles and ultimately failure. Installing a screed, of suitable thickness over the bituminous waterproofing compound is recommended.

Liquid applied membranes (LAM)

Liquid applied membranes are monolithic, fully-bonded, liquid-based coatings, typically polyurethane or acrylic-based, which cure to form a rubber-like elastomeric waterproof membrane.

Advantage: ready to use, easy application and compatible with cementitious tile adhesives and levelling compounds.

Note: When left exposed, regular maintenance inspections should be carried out, and remedial work carried out as soon as any damaged or deteriorated areas of waterproofing are found.

Sika – Bosjes Chapel, Waaihoek

Cementitious waterproofing compounds

Cement-based products that are available as waterproofing compounds, or mortars.

Advantage: Compatible with cementitious tile adhesives and levelling compounds.

Self-healing products

Crystalline products react with the water and free lime in concrete, to form crystals which effectively fill any small voids within the concrete and make it watertight. It can also be used as a self-healing product to repair cracks in the concrete, as the crystals will continue to grow over time. These products are available as either a powdered crystallising admixture or a crystalline cementitious penetrating coating.

Advantage: Chloride free, safe to use with potable water storage, wastewater etc.

Waterstops

A specialised and technical product, designed for waterproofing construction joints with preformed flexible strips. Waterstops are used for construction joints in dam walls, reservoirs, sewerage tanks and other water-retaining structures constantly exposed to hydrostatic pressure.

a.b.e. Saint-Gobain – Waterstop at Kruisfontein

There are two types available:

Full thanks and acknowledgement go to www.abe.co.za, www.mapei.com, www.tal.co.za and www.zaf.sika.com for the information used in this article.

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