Globe & Simpson Newbuild Basement Waterproofing

This new development was waterproofed with pre-applied external tanking membrane and concrete containing a waterproof admixture. Barrier tanking combined with an integrally waterproof structure can (and did) leak. Trace designed and installed internal cavity drainage to protect a habitable shower block area within the development.

Globe & Simpson Newbuild Basement Waterproofing

Job type:


External pre-applied tanking membrane combined with admix. concrete, both installed by ground-workers, suffered some leakage

Habitable shower block required a grade 3 (totally dry environment) to protect the finishes being installed

Trace were asked to design and install the Type C cavity drainage waterproofing to provide this

Trace flood tested and found issue with a pre-formed discharge pipe detail, subsequently addressed

Cavity membranes installed to walls and floors

Dual pump and battery back-up system installed to remove water

The Property

Conventional cavity drainage waterproofing was specified and installed by Trace to mitigate localised areas of ingress through the basement structure.

Drainage must be verified either via levels survey or flood testing, this should always be undertaken when installing cavity drainage to identify that the system will discharge any water that is collected within it.

In this case a pipe had been cast into the structure to allow water to drain to a sump in an adjoining room. From visual inspection, this appeared to be higher than the slab floor level, which could represent an issue for discharging water to the sump.

Pipe appeared slightly high.


Flood test

To prove the outlet level issue we flood tested the treated area. Note that this area was on one side encapsulated by a block laid on edge, which subsequently had metal frame dry lining constructed over. This blockwork was tanked to form a bund detail, so that water could not escape to other areas of the basement. Hence, the flood test was also to check that the bund was defect free and held water.

Remedial action.

The bund held water without issue, but the outlet was indeed too high as proven by the flood test. The discharge detail was addressed by diamond core drilling to lower the connection to the sump system, and the system was then completed as pictured above right.

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