In Case Studies

Delta Membranes‘ expertise ensures the new basement in the Portman Estate’s 90,000 sq ft redevelopment of 1-9 Seymour Street is perfectly waterproof despite the challenges of working within a multi-facaded property.

As with any basement construction, consideration to groundwater, soil type, precipitation, topography and ground conditions/site analysis needed be addressed. On 1-9 Seymour Street, Delta’s approach was to carry out full and thorough check and to make a decision on what types of waterproofing would be best suited to this project, as no two projects are identical.

Waterproofing a basement ensures that the integrity of the structure is preserved whilst ensuring the usefulness of the same. All basements should be constructed to cope with groundwater levels up to the full retained height of the basement. BS8102: 2009 sets out the scope and limitations for below ground structures.

An initial and important consideration in the overall waterproofing strategy was to ensure that all construction joints were appropriately detailed and waterproofed using Hydrophylic waterstops. Through knowledge and experience Delta’s advice was to incorporate two forms of waterproofing into the design. With over 2500sqm to cover Delta Membrane Systems Ltd’s NB1 in-depth migratory crystalline slurry (a Type A System, a water barrier), and Delta MS500 and MS20 (a Type C System, cavity drain membrane system) would be a great solution.

Koster NB1 is a crystallizing mineral waterproofing slurry system which has a capillary plugging agent ideal for sealing against pressurized water (> 13 bar) and is watertight (>130m water head). Koster NB1 is a Type A waterproof system as set out in BS8102:2009. NB1 is suitable for new builds and in restoration properties. Koster NB 1 Grey is characterized by its excellent resistance to pressure and abrasion as well as excellent resistance to chemicals.
Koster NB1 was applied using a peristaltic pump which provided a uniform spraying application, this method saves considerable man hours and is a great way to ensure complete and even coverage.

Having applied a Type A waterproofing system a secondary Type C system offered a robust waterproofing design.

The finished project will be a truly stunning building that adds to the growing portfolio for all involved and will add to London’s ever evolving skyline and landscape.

Read more about the project here.

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