March 2006
Common Problems - External Tanking
Detail
Waterproofing
of retaining walls on single-sided basements, sloping
sites or step changes in modular floor construction
is a perennial problem.
The current Building Regulations and BS 8102:1990 (Protection
of structures from ground water), stress the importance
of, where possible, (i) maintaining the continuity of
the waterproofing system, (ii) avoiding breaking the
integrity of the waterproofing with wall ties and (iii)
the desirability of cross flow ventilation.
Two typical drawings which illustrate how to overcome
these issues are available for download by clicking
on the links below..
View
Retaining Wall detail
The concepts shown
in these details can be adapted to incorporate many
of the typical structural requirements by the Structural
Engineer. The main benefits of this solution are as
follows:
- Water can effectively pass through
the outer leaf and into the void beneath the suspended
floor.
- Wall ties are screwed into the brick
plugs used to fix the Cavity
Drain system thus tying the two masonry
skins together without puncturing or breaking the
integrity of the waterproofing.
- Continuity of the waterproofing
system is maintained using a Flexible
Polymeric DPC.
- Cross flow ventilation through the
Cavity
Drain system is provided by incorporating
weep holes / air bricks in accordance with good practice.
- This solution can also be adapted
to accommodate Radon gas as shown in detail SD
/ Typical / 007
Please note:
Consideration should always be
given to the position of the water table and drainage
characteristics of the sub soil when designing
your waterproofing strategy.
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