Residential basement conversion, Kent

26 July 2018


Basement type: Refurbishment Building type: Residential
Type of waterproofing: Type A & C Member: Delta Membrane Systems
Other: Heritage  

The Project

Timberwise’s (South East) team were called upon to investigate a property with an existing basement in Sittingbourne, Kent, that was suffering with damp. The property is a typical Victorian (circa 1900’s) semi-detached, brick built dwelling.

The project was to change the basement into a habitable living space and to provide the most effective waterproofing solution to resolve the damp issues. Changing a basement into a habitable living space offers a flexibility of uses, as a basement sits close to the main living areas of a property. Typical of the Victorian era, the property when constructed incorporated a basement and it would have been used to store coal or to house servants.

Sittingbourne, Kent is 17 miles from Canterbury, 45 miles from London and sits next to the Swale (a strip of sea separating mainland Kent from the Isle of Sheppey). A full inspection of the basement was carried out by a Waterproofing Design Specialist. The first stage of the process was to carry out profiled moisture meter readings on the wall surfaces. Using a moisture meter to ascertain damp readings, high readings were observed. There were no existing sump pits, open gullies or natural drainage within the basement and the basement showed no signs of any flood water having entered the building previously.


Waterproofing a basement ensures that the integrity of the structure is preserved whilst ensuring the usefulness of the basement. All basements should be constructed (or retrofitted) to cope with groundwater levels up to the full retained height of the basement. The main areas of potential weakness (where moisture could penetrate into the basement) were the wall/floor junction. The basement has a solid floor, on a mortar bed. Other areas of concern observed included the potential for moisture ingress caused by the lateral penetration of capillary holding moisture. 

All Timberwise waterproofing systems are designed by a Waterproofing Design Specialist in accordance with British Standard – BS 8102:2009 “The Code of Practice for Protection of below Ground Structures against Water from the Ground”. BS 8102:2009 sets out the limitations and scope for below ground structures, areas covered include:

  • waterproofing barrier materials,
  • waterproofing to construction joints,
  • ensuring buildings are structurally integral with watertight construction,
  • drained cavity construction,
  • ground water assessment,
  • ground water drainage; and
  • associated risk assessments.

Consideration was given to managing future water ingress issues. A Cavity Drain Membrane System was the solution recommended and the Delta Cavity Drainage System was installed.

System Components

MS500 – is a cavity drain membrane that is suitable for waterproofing walls, floors and vaulted ceilings, above and below ground, in new construction or in existing buildings over a contaminated or damp background. MS20 – is a heavy gauge membrane with deep 20 mm studs. This is used where extra drainage capacity is required, for example on deeper structures or where a larger flow rate is required. Delta MS20 can also be used as a “cavity former” for numerous types of new construction.

Cavity Drainage Channel - A cavity drain system was installed with maintainable drained channels to allow for the free flow of water to the pump or pre-determined exit point. A perimeter drainage channel was also installed complete with inspection ports for easy maintenance.

Dual Pumping System - A Delta packaged pump station was designed and installed to collect groundwater via the perimeter drainage channel. This chamber can also be used to collect grey water from showers and washbasins.


The basement was transformed into a dry, habitable living area by Timberwise and the customer was delighted with the end result. The customer also benefited from Delta’s long-term guarantee* that their basement would remain dry offering extra peace of mind.

* The Delta 30 year guarantee on their Cavity Drain Systems is only available when installed by a Delta Registered Installer.

See Delta Membranes Systems company profile