Structural
waterproofing system for three new build houses in Leicestershire
The underground
structure of a new build housing project in Leicester needed an effective
structural waterproofing system. As a requirement of the National Housing
Building Council (NHBC), the complete external wall to one of the three
plots would be 3m beneath the finished damp proof membrane. A
waterproofing system was therefore required to ensure the structure was
resistant to the water table and probable water ingress.
Original plans showed land drains to be
installed around the perimeter. However, following a detailed inspection
and to comply with BS8102 2009 guidelines, a primary membrane and double
drain system was recommended to be installed at the base of the foundation
slab with drainage connected to a maintainable drain outlet. This would
allow for control of free water and dampness and also provide a dry
waterproof inner skin acting as a vapour control layer.
Vapour membrane was painted to the
foundation slab and surrounding surfaces. An angled floor wall joint was
applied to the block wall and foundation slab. The double drain was then
fitted to the entire wall across and down the side of the foundation slab
with careful positioning of the drainage pipe, essential to ensure water
had the means to be channelled away effectively. Filter fabric of the
membrane was positioned to prevent soil entering the membrane cavities and
impede drainage. The land drains were then installed to the water outlet
before the whole area was back filled with great care taken to ensure no
damage occurred to the membrane.
The waterproofing system was designed
and project managed to ensure correct installation and all works complied
with the NHBC and BS8102 documents in order for a guarantee on the system
to be provided. The work was approved by the NHBC on completion.
This case
study has been submitted by a member and the British Structural
Waterproofing Association accepts no responsibility for its content.
