The brief for this project was to design, supply and install a bespoke and sympathetic waterproofing solution to a Grade II listed, commercial structure with an impractical damp basement.

Delta Registered Installers, MacLennan Waterproofing worked closely with the Principal Contractor, HB Projects to achieve a Grade 3 habitable space whilst preserving this historic structure.

The Co-op shop in Petworth Village, provides the local community with everything they need, whether its household essentials or a place to meet friends.

The site incorporates two Listed Buildings, including part of a Listed Church. The store applied for listed building consent to reconfigure its ground and basement floors, to increase the retail floor space and improve the functionality of the store.

When designing a waterproofing/damp proofing solution in a historic building or a structure of architectural interest, additional design considerations should be employed during the design stage to maintain preserve aesthetic and structural integrity of the structure/building.  The waterproofing design should be sympathetic in application whilst offering a robust solution.

Care consideration should be applied when specifying products to ensure they are ideally suited for meeting the complexities of listed building requirements.


Ensuring that the project was fully compliant with BS 8102:2009 (Code of practice for protection of below ground structures against water from the ground), MacLennan recommended a Delta, Type C internal cavity drain membrane system.

Not only is Delta’s Type C system reliable and completely maintainable, but it is also an ideal choice for heritage structures and structures of architectural interest.  Delta’s ventilated Type C system is favoured by English Heritage, The Society for Protection of Ancient Buildings (SPAB) and local authority conservation officers because the system itself does not require any aggressive preparation and is reversible, retaining the structures original form, whilst protecting finishes to create a warmer, dry, and habitable environment.

The project was split into 2 phases.  Phase 1 construction and remedial works and Phase 2 installation of the waterproofing system.

Phase 1 – involved moving partition walls, relocating the kitchen, and excavating additional space in the basement to install a scissor lift and a new staircase.  Within Phase 1, MacLennan undertook strengthening and repairing the structure, ready for Phase 2.

Phase 2 – installation of the Delta system.   Firstly, installation of the perimeter drainage channel around the wall floor joins and wall mounted inspection ports to allow easy access for inspection cameras to check the channels during servicing.  Delta MS 500 ventilated cavity membrane was installed floor to ceilings, with Delta MS 20 being laid to the floor.

A Dual V3 sump and pump were also incorporated into the design to remove any potential water ingress. Sump pumps are critical when complying with waterproofing standards and ensuring any water ingress is safety evacuated to a suitable discharge point.

The works were carried out by MacLennan’s fully qualified, expert technicians and installed to the highest quality.

Case Study Results

The local village shop has a fully functioning and completely dry basement area which can be used for storing extra stock whilst offering a comfortable staff area and office space.  MacLennan completed the works within budget and agreed time scales and provided full company guarantee. All design and works are covered by MacLennan’s 10 million PI.

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