Waterproofing for buried decks

Buried decks are an increasingly common feature in the modern built environment. This increase may be partly attributed to growing awareness of the need for sustainability. Green roofs, sustainable urban drainage, water attenuation and even parks and farms are being located on top of ground floor roof structures and cut and cover tunnels. Waterproofing of these decks is vital in order to use the space created beneath and, also, to prolong the life expectancy of the structure. This research explores some of the available best practice guidance and then compares the key waterproofing design features with opinions from industry. Opinions are gathered through seventy-eight questionnaire respondents made up of UK based professionals dealing with waterproofing of buried decks. This research suggests that buried deck waterproofing design can reduce risk by employing the following features: (a) reinforced concrete structural deck, (b) fully-bonded waterproofing membrane, (c) waterproofing laid to a gradient to falls, and (d) provision of a drainage void over the waterproofing layer. As a result of these findings this paper calls for more authoritative best practice guidance on buried deck waterproofing design in a bid to reduce pressures in procurement that lead to weaker waterproofing design choices. This research may be of interest to those involved in the design and construction of underground structures including cut and cover tunnels, station boxes, malls, basements and more. The research identifies some fundamental features of podium deck waterproofing design and clarifies which design choices are perceived to deliver more robust waterproofing than others.