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23 May 2019

Below-Ground Structural Design for Tanking

Volclay Voltex Allco3

There are many factors that contribute to below ground design, which means a lot of questions to be asked: 

Is the wall structure a pile face (soldier pile, contiguous pile, steel round and sheet pile, secant pile) or in-situ concrete, block, pre-cast panel, dincel (plastic exterior surface), AFS (cement board exterior surface) or shotcrete (very applicator reliant)?

With all these possibilities comes a variation of concrete quality: some are more porous, some less dense or stable, leaving the MPa (megapascal — compressive strength) a key element to consider when selecting your choice of wall (both for waterproofing as well as overall requirements).

Then there is the quality of concrete placement. Sometimes contractors may allow too much water build-up at the base of an in-situ wall which allows the cement to wash away at the base, leaving bony concrete which is not good structurally or waterproofed easily.

Then comes the design. Is the floor poured first or are the walls constructed first? Is the wall sitting on the FFL (finished floor level) or is there an elevated floor? How do the perimeter and sub-floor drains work with the design? Is there any water control? What are the hydrostatic conditions?

There could be a combination of all the above due to one side of the construction site being on the boundary with little or no access, another side with access but a confined space, and the remainder being very accessible. A different site may join the existing building with a new building.

Considering all the above factors mentioned, a short meeting with an experienced below ground waterproofing advisor is very beneficial. This short meeting at the onset of the design can lead to ongoing decisions which can help improve cost and time efficiency and the ultimate result: a dry basement.

Without the meeting, the waterproofing details may well require elaborate additions, leading to extra costs.


Choose your contractor wisely (one who has reliable sub-contractors), choose your waterproofing system wisely and choose waterproofing applicator wisely.

Remember the triangle of choice: 

An offer can be good quality, cost-effective and fast. BUT you can only choose two: 

If you choose a good quality and cheap option, it will not be fast.
If you choose a cheap and fast option, it will not be good quality.
If you choose good quality and fast option, it will not be cheap.

View more information on Allco Waterproofing Solutions, including contact details.
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