Basement waterproofing for a three storey detached apartment building


20mm floor membrane, 2 x No. 650mm cubed sump chambers


A Victorian spa town nestled within a designated Area of Outstanding Natural Beauty and often affectionately known as “the heart of Yorkshire”, North East Surveyor Martin Wilkinson was called upon to carry out a survey on a three storey detached apartment building in one of the most sought-after areas in Harrogate. Martin was instructed to inspect the lower ground floor basement as the client wanted this to be converted into habitable accommodation as well as an extension. This would include a lounge with adjoining snooker room, a wine cellar, exercise studio, hallway and cloakroom.

The client knew they could trust our Timberwise Basement Waterproofing Contractors to design, install and guarantee a solution that would not only meet all of their specific needs but also meet NHBC guidelines which included two forms of waterproofing in the form of an external barrier and an interior maintainable barrier.

The Waterproofing Design Methodology

For the new build extension, a Type A system consisting of an external waterproofing barrier was specified to the outside face of the structure. This was combined with a Type C system applied to the entire internal surface of all of the rooms.

Type C

A Type C system involves the use of cavity drain membranes to internal walls and floors, which includes internal drainage channels and pumping stations as a means of exiting water from the basement.

Cavity drain membrane was applied and fixed vertically and horizontally on the floors alongside a perimeter drainage channel, two separate sump chambers both incorporating two pumps and a battery back up giving the customer complete peace of the mind that the system will still work in the event of a power failure.

Prior to any waterproofing works, it was important to treat the concrete floor with a lime pre-treatment to ensure that there were no lime deposits that would track through and potentially block the free flow of water on the floor between the membrane and the slab prior to it entering the channels and sump chambers.

Timberwise worked closely with the finishing contractors to advise of the installation of fixtures and fittings, so as to ensure the waterproofing system maintained its effectiveness and integrity. Following completion of the waterproofing works the entire basement was completely dry, clean and water free, and with the installation of a central spiral staircase made for a real feature within the property.

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