An example of substantial water ingress and flooding, via unsealed service pipe penetrations.

https://vine.co/v/OEYY9vmZpgV/embed/simple

What caused this??

…Well compacted concrete is an inherently water resistant material, and with sufficient depth it can essentially block water out, however concrete structures leak. Why is this? Well, one way to think about it is that water penetrates not where the concrete is, but where the concrete ‘isn’t’ (a description I pinched from Bob Cather).

Where might concrete not be, within a concrete structure?  Such positions might include: through cracking, construction/day joints, movement joints or induced crack joints (neither of which are a good idea in a basement), and the focus of the example, which as per the clips above, is the service penetrations.

We were contacted before Christmas by a family suffering at the hands of a problem basement plant/store room, within a new-build property in very wet clay ground, where the structure is formed in reinforced concrete, tanked externally with bitumen sheet membranes (…like a bad penny), then subsequently tanked internally as an attempted remedial measure, this using polymer modified cementitious tanking slurry.

The space continued to suffer ingress and the homeowners were having to manually wet vac up the water following rainfall, sometimes throughout the night, this to prevent the space from flooding, which put plant – ground source heat pump equipment and electrical plant etc., at risk.

While water was moving through the external tanking, structure and internal tanking, a primary point of ingress was at high level service penetrations at the top of the retaining wall, as per the photo below:

See my blog post at: http://basementwaterproofingexpert.co.uk/2015/03/10/service-penetrations-how-bad-can-it-be/