Staying Dry: A Homeowner’s Guide to Waterproofing (Part 1)

The concern of waterproofing a home is not one normally entertained by property owners, that responsibility typically falls to developers who may subcontract that scope of work to specialists. But with all the rainfall we receive in Malaysia, we put together this definitive two-part guide to help property owners identify potential leaks before they happen, and in Part 2, to select the appropriate materials for waterproofing.

Part 1: Identifying Potential Problem Areas
The identification of areas to be waterproofed is critical in defining the treatments to be applied and the costs involved. The areas of a home that are known to be the typical starting points for leaks are places where water is found in abundance, and especially areas with pipe penetrations through a concrete slab or wall. These areas include roofs, bathrooms, kitchens, as well as water features such as swimming pools and fish ponds. Other areas of concern may be walls composed entirely of brick, which can present leaking problems as the gaps between bricks allow for water to wick in and break apart the mortar through the absorption and expansion of water vapour over many days of alternating rain and shine.

A brick wall after losing another fight to its archnemesis – water. Image Source

1. Roofs
Some modern bungalows, and the extensions of terraced houses, are constructed with flat concrete roofs instead of conventional angled and tiled roofs. While this method of roof construction may be preferred for its aesthetics and relatively low cost, it presents some concerns wherever stagnant water may collect. An unprotected concrete structure will absorb and dispel water through evaporation over time, and the constant cycling between absorption and evaporation deteriorates concrete and weakens structures with the formation of cracks.

Leading to a garden inexplicably growing on the roof. Image Source

Flat concrete roofs are generally built “to fall”, meaning that the horizontal surface is levelled with a slight slope to enable allow water to flow away instead of forming stagnant pools. This level is difficult to achieve when measured over larger areas and especially when the finishing trowel work is done by the hands of anyone other than a skilled concreter.

A concrete roof with a slight slope “to fall” to ensure water flows away. Image Credit: Kevin Eichenberger

2. Bathrooms and Kitchens
Different areas call for different treatments – bathrooms with showers should be waterproofed beneath the tiles to a greater extent than kitchens, with treatments to walls going up to at least 1.2 meters from the floor to prevent splashes of water from seeping into walls. Kitchens and other similarly wet areas will benefit from skirting to walls going up to as little as 30 centimeters, as wet floors resulting from cleaning could lead to moisture wicking its way up walls.

Due to the relatively high frequency of use expected of bathrooms and kitchens, one can expect the faucets in these areas to become loose and drip water over time. When presented with a wet patch appearing on a ceiling, one can likely expect to find the culprit is simply a dripping faucet leaving pools of water to soak between tiles and into the concrete.

Changing the faucet or reinforcing leaking connections with some plumber’s thread sealing tape should yield a positive result immediately. If such wet patches persist, then the concrete is still saturated with water, which necessitates a more intrusive repair of the tile grout or the waterproofing layer beneath tile finishes.

3. Water Features

Water features such as swimming pools and fish ponds should be treated beneath their exposed finishes up to and above the intended waterline. However, the challenge with these functional water features is selecting a waterproofing material that can withstand the onslaught of the nutrient-laden contents of fish ponds – or chlorinated water, in the case of swimming pools.

An additional consideration is the pressure generated by large volumes of water. The body of water in a swimming pool will push harder against the walls at the bottom than at the top, meaning that a leak will likely spring from the bottom-most part of the structure, necessitating a greater amount of reinforcement and a greater thickness of waterproofing treatment at the lower extents of a water-holding structure. Homeowners should consider forming chamfers at the intersections between the walls and the floor of water features to alleviate some stress on the structure, in addition to ensuring that the structure is waterproofed on the inside.

While it makes for a stunning view, whoever owns the property directly below this infinity pool would be paying exorbitantly high premiums for broader definitions of “foreseeable” and “acts of God”. Image Source

Article by Kevin Eichenberger