Previously, in Part 1 of this two-part guide on waterproofing, we mentioned how potentially problematic areas of a home could be identified. In Part 2, we talk about the various materials and treatments that can be applied to keep your property dry.
Part 2: Selecting Appropriate Materials
The methods and materials used in waterproofing treatments are varied, ranging from the lowest-cost, brush-applied cementitious coatings, to industrial-grade synthetic membranes that are manually adhered to concrete. Brush-applied cementitious coatings are the simplest to acquire and use, with the ingredients (ordinary cement mixed with an acrylic liquid) being sold out of hardware stores. On the other end of the scale, bituminous and synthetic membranes provide more certain protection from moisture (especially for concrete structures below the ground) but involve laborious application and complicated materials that may be toxic or difficult to handle.
1. Cementitious Coatings
Cementitious coatings are the most commonly used treatment in the majority of housing developments due to their low cost. The downside of this low-cost treatment is a relatively short lifespan due to the brittle and rigid nature of cement. These coatings can deteriorate from the physical damage caused by falling water striking the surface, consequently they are usually applied beneath a protective finishing such as tiles – albeit in one or two coats, resulting in a treatment that is only a few millimeters in thickness and prone to deterioration wherever the grout (the spaces between tiles) has been compromised.
2. Flexible Coatings
Flexible coatings are available in a range of formulations that generally involve synthetic polymers mixed with pigments and other additives to provide structures with more durable waterproofing relative to cementitious coatings. Flexible coatings tend to be sold in cans similar to conventional paint, and most can be easily applied with a roller or brush. Depending on their formulation, flexible coatings can endure considerably more physical damage than cementitious coatings and are preferred for guaranteeing protection from moisture in commercial spaces.
Concrete structures that are buried in earth, such as underground parking garages, elevator shafts, swimming pools, or water tanks, have to endure a greater level of moisture from the ground. Coatings are generally no thicker than a few millimeters and cannot withstand the physical damage caused by backfilling – the process of burying a concrete structure in earth.
When a coating gets thick enough, engineers start calling it a membrane instead. Membranes are usually made available in rolls of sheet materials and occasionally composed of bitumen, or synthetic compounds, that are either adhered to concrete structures by way of an adhesive layer, or by melting one side lightly with a torch before application.
Membranes are among the most durable waterproofing treatments available but are also among the most expensive methods due to the high involvement of labour. Due to the combination of high cost and high durability, this type of treatment is usually found in commercial and industrial applications to below grade (buried) concrete structures.
Article by Kevin Eichenberger