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DAMAGE ISSUES WITH Nearly 80 per cent of building faults in sub-basements and car parks are related to waterproofing failures, making ineffective waterproofing one of the biggest problems faced by the building industry today, according to the Australian Institute of Waterproofing.
Despite Australia being known for its dry climate, water damage can affect projects on every level including terraces, decks, courtyards, balconies, sub-basements and car parks. Unfortunately water damage can be more than just an inconvenience. It can cause long-term structural problems in buildings, and lead to flooding and property damage – especially in occupied areas like sub-basements and car parks. Good drainage is essential if you want to ensure your property and structures are protected, but traditional paving and drainage systems often come with a number of limitations. Sub-basements and car parks can be particularly vulnerable to water damage and flooding, as they are often located well below ground-level. This is becoming an increasing problem as with a growing shortage of street level parking in urban areas, increasingly more car parks are being located underground. This leads to a need for more effective below grade, negative pressure waterproofing. The good news is that many waterproofing failures can be prevented. With adequate knowledge and understanding of the causes of membrane damage and the right systems in place it’s often not too difficult to alleviate the problem. Developments in technology have increased the options for those who are looking for a cost-effective way to get rapid surface drainage, while still allowing access to the waterproofing and services beneath – and for effective waterproofing of their subterranean basements and car parks.
What’s wrong with traditional paving and drainage systems? Traditional paving systems have a number of downsides over the more innovative modern paving systems out there. To start with, traditional paving systems can be susceptible to unwanted and unattractive efflorescence staining, which means their appearance will start to deteriorate over time. Beneath the surface there can be other problems with traditional paving systems. Installation of pavers on sand cement usually requires multiple trades, tools and materials. These are all potentially hazardous to the membrane and can lead to damage and leakage. Cracking and staining of pavers means regular repair is often needed, and this can also damage the integrity of the membrane. Ponding can cause damage Ponding is common on traditional paving systems, and this can cause damage to the mortar bed and affect overall paver stability. With traditional systems it can be very difficult to gain access to the membrane to repair when a fault is identified. Bedding pavers or tiles can prevent access altogether. This difficulty in accessing damaged membranes can mean minor issues are left untreated until they get out of control and lead to long-term, costly structural damage. Leakage coming down from the surface can cause ongoing issues in subterranean areas including car parks and basements, especially if their waterproofing isn’t up to standard. Older forms of waterproofing for basements and car parks are often insufficient to withstand water pressure, which can lead to them being vulnerable to damage. In many cases, waterproofing problems aren’t detected until too late with traditional paving methods that can conceal problems, especially if the area is constructed over a habitable space. In many cases a serious structural issue is the first indication of a problem and, by then, the damage is done and major repairs will be needed.
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Adjustable drainage can eliminate problems Fortunately, adjustable paving and drainage systems can provide many buildings with a way to eliminate a significant proportion of the waterproofing problems caused by traditional systems, and reduce the likelihood of structural damage going undetected. Adjustable paving supports consist of height adjustable pedestals that go underneath pavers, allowing the finished surface to be level. This creates a cavity that improves insulation and facilitates rapid surface-drainage while, at the same time, keeping services and waterproofing accessible. There are a number of different adjustable paving systems available to meet different requirements, from roof gardens and balconies to basements and car parks – and everything in between. Although they may vary slightly, these systems are all easy-to-install and provide a flexible, cost effective solution for any space. Unlike traditional paving systems, adjustable paving supports eliminate ponding and efflorescence. Surface water moves quickly to the 4mm wide open-grout joints to the cavity, minimising any back up of water during heavy rain events. This eliminates the need for expensive and often clumsy drainage grates. The adjustable paving supports can also reduce the load on slabs, improving their structural integrity while helping to reduce cracks and other damage. There is no mechanical fixing required when using adjustable paver supports. The supports simply sit on the membrane and are locked in
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place by the paver joint tabs. This allows easy access without the need for heavy tools that run the risk of damaging the waterproof membrane. Because the height and slope are adjustable, it’s easy to create a level finish even when the pavers are of inconsistent thickness. Adjustable paving support systems like VersiPave are commonly used in major civil construction projects and buildings to allow long-term access to the membrane. Under slab, planter box & vertical sub-surface drainage solutions Systems like VersiCell are commonly used for car parks and subbasements, as they are designed for sub surface drainage and waterproof membrane protection. Once they are installed with a waterproofing membrane there is no need for an additional layer of protection. The VersiCell modules are able to withstand heavy loads of up to 100 tonnes per sqm, including those imposed by mechanical equipment like bobcats and wheelbarrows. VersiCell is also used extensively in major civil construction projects as a drainage solution, most recently as a rising ground water management tool under multi-story building slabs. Geofabric is installed over the cut profile, followed by the VersiCell and waterproof membrane. This enables builders to eliminate the need to excavate and dispose of huge amounts of cut spoil. The cell will discharge water at a rate of 16.5 litres per sqm each second, which outperforms traditional drainage methods of crushed aggregate by approximately tenfold. Ground water is then collected in pits and pumped back to the surface as either irrigation or storm water. VersiDrain 8 mesh is a high strength dimpled HDPE drain sheet that is ideal for managing negative side water. This solution was used on the Chatswood to Epping rail link where a 25-50 mm layer of ‘shotcrete’ was made, followed by a liquid-applied waterproofing membrane. Exactly 100mm of shotcrete was then applied. Don’t let long-term water damage affect the structural integrity of your buildings. By switching to adjustable paving supports and high-flow drainage cell, you can enjoy a system that’s cost effective, easy to repair and maintain, drains more effectively. It will also soundproof and reduce transmission of radiant heat.
Ken Hitchcock is director of KHD Landscape Engineering Solutions (KHD). KHD offers a wide range of landscape engineering and natural stone products (www.khdlandscapesolutions.com.au/stone-products) for domestic, commercial and local government projects. Having been in business for over 15 years, KHD are well known in the industry for their high-quality products, and ability to work with other industry professionals to achieve the best possible project and client outcomes.
For more information: Phone: 0419 579 437 Website: www.waterproof.org.au Contact us for our full range of Waterproofing, Moisture Barrier and Concrete Protection products.
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