Concrete Basement Gas Protection

Leafy Windlesham in Surrey was the location for this 5-bedroom, £15,000,000 mansion by Searchfield Homes, complete with a 4-metre deep basement containing a swimming pool and spa pool, all of which needed to be protected from water ingress and ground gases.

The Project

Considering the prestigious nature of the property, the high water table, and the risk from ground gases, Newton Specialist Contractor Maclennan Waterproofing were contacted by the architect to provide a specification combining waterproofing and ground gas remediation, as well as providing an insurance-backed installation guarantee.

The Solution

Maclennan recommended the patented Newton PAC-500 System to protect against both gas and water ingress. The PAC-500 begins as a Newton CDM System by Maclennan’s installers, all of whom have obtained or are working towards their Level 2 NVQ qualification. Newton 508 membrane is installed to the walls and floor, with MultiPlugs to secure it and Waterseal Tape to seal the joints. Water captured by the membrane is then directed via a series of Basedrain and Floordrain channels to a Titan-Pro sump and pump chamber.

During the installation process Maclennan also worked closely with specialist gas remediation contractor Prestige Air in order to convert the CDM System into a Positive Air Curtain (PAC) System too. This was achieved by fitting an air duct behind the membrane at ceiling height around the basement, then using a high volume, low-pressure fan to deliver a curtain of air behind the membrane, blocking gas from entering by creating a continual flow of pressurised air.

The Result

By utilising the specialist expertise of both Maclennan and Prestige Air from an early stage, the architect and client benefited from a combined system that not only protects against both water and gas, but is also compliant with all relevant British Standards and supported by Maclennan’s insurance-backed installation guarantee.