North London Basement with Spa Facilities @DeltaMembranes

System Components

  • Delta MS500
  • Delta MS20
  • Qwikseal Plugs
  • Double Sided Tape
  • Corner Strip
  • Fleece Tape
  • Drainage Channel Inc Upstand
  • Drainage Channel Corner Units
  • Drainage Channel Straight Connectors
  • Jetting Ports
  • Dual V6 Sump
  • AlertMaxx 2 Ground Water
  • Dual V4 Sump
  • AlertMaxx 2 Ground Water
  • Bespoke Dual Foul – 800×1300
  • NB 1 Grey
  • Polysil TG500



BS8102:2009 Code of Practice for the Protection of Below Ground Structures Against Water from the Ground.


The scope of this project was to demolish an existing 1960’s detached dwelling in the heart of Totteridge, North London and to construct a new build luxury house.  The proposed new build construction would be a 2-storey detached property incorporating a basement, loft with rear dormers and associated soft and hard landscaping.

The key features of this project included a swimming pool, gym, sauna, steam room and games room in the basement.

Delta Registered Installers Polytech were approached to undertake the waterproofing design and installation having undertaken many projects in the past utilizing a various range of merchant available products but sought reassurance with the products and back-up from Delta as the design requirement was to be robust for this high-end structure.

Polytech took into consideration that good design and workmanship are primary factors in achieving successful waterproof construction. Along with other key considerations such as compatibility of waterproofing systems, sealing around joints and junctions within the basement structure and for integral structural waterproofing systems to offer attention to weak areas, such as construction joints.

Polytech were keen to creating a design which was both compliant to British Standard 8102:2009 2009 ‘Code of Practice for Protection of Below Ground Structures Against Water from the Ground and practicable. The project required Grade 3 protection – No dampness or water penetration is acceptable.

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Having undertook site investigations and considerations a Cavity Drain Management System was specified for this project in conjunction with Waterproof concrete affording compliance with a structural warranty.

In principle a cavity drain membrane system allows moisture or running water that does bypass the structure to travel behind the membrane within a controlled drainage system.  A cavity drain system requires minimal preparation and disturbance to an existing substrate.

The basement walls and floor slab once constructed were given a coat of Koster Polysil TG 500, an anti-lime inhibitor.  When new concrete is introduced to structures there is a risk of excess free lime leaching out during the curing process, this free lime if untreated can enter the cavity drainage system (impeding the flow of water and potential to cause sump pump failure).

Swimming Pools can be challenging from a waterproofing perspective and dealt with in several ways. The Pool box was formed on top and in front of the Cavity drain membrane which is capable of taking 150Kn and 250K/n respectively, these loadings allow for continuity of the waterproofing.

Delta Channel was incorporated into the basement floor area, with access ports to allow for future inspection and maintenance of the channel system.

Attention was given to all weak points of construction such as the floor/wall junctions, which were adequately protected from any potential water ingress.

Koster NB 1 grey was applied to the basement floor and walls.  Koster NB is a mineral coated waterproofing slurry which contains capillary-plugging agents making it an ideal solution to protect a structure from ground moisture both for non-pressurized and pressurized water.

The waterproofing system concluded with a Type C System, Delta MS 500 applied to the basement walls and MS 20 applied to the basement floor. A Type B waterproof concrete was also deployed.

The project required a V4, V6 sump pump and bespoke foul water pump to accommodate drainage.

Polytech opted to incorporate the AlertMaxx 2 high level alarms which offered the customer further confidence.  High level water alarms are used to provide a warning of pump failure.  The AlertMaxx2 is an intelligent high-level water alarm and monitoring system which performs regular health checks on the pump system ensuing pumps are running efficiently.

Case Study Results

Polytech’s design in conjunction with assistance from the Delta technical team achieved compliance with BS8102:2009 as a minimum. Their design and quality control procedures sought to redefine waterproofing, in a cost effectively manner above and beyond standard requirements.

The customer was thrilled with the project and Polytech’s logical and professional approach.