Waterproofing An Existing Historic Leaking Vault

Waterproofing An Existing Historic Leaking Vault Overview Vaults are a common feature of 18th and 19th century buildings in Bath. Originally built to support the cobbled streets above and were a constructional response to the precipitous topography that surrounds Bath, in order to provide a level site. Bath’s vaults are said to be an integral part of the area’s historic integrity in both architectural and social historic terms. Although vaults in Bath are subterranean spaces, they were built on what was the original ground level. Many of the vaults within historic Bath suffer with water ingress and damp related problems. Delta Registered Installers, Cannon Clarke were commissioned to design and install a guaranteed waterproofing solution for Po Na Na, a Moroccan-themed nightclub venue situated in a vaulted cellar in Bath’s popular Parade area. The vault was suffering high volumes of water ingress during rainfall due to the road above. Methodology During initial onsite inspections, it was evident that the original tanking system used within this venue was failing. It’s believed the vault had originally been tanked over 50 years ago. In keeping with the Local Planning Authority’s position in determining listed building applications for their alteration and for damp proofing works, it was agreed that the venue owners could update the tanking system. Cannon Clarke designed and installed a Type C Drained Protection waterproofing system incorporating Delta’s BBA Certified MS 20 and MS 500 membranes. The walls were treated using Delta MS 500 Cavity Drain Membrane. The Delta MS20 and MS 500 Membrane Systems have been specified in many Grade 1 and 2 listed buildings throughout the United Kingdom due to its sympathetic value. The Delta Membrane System offers an ‘air gap’ technology which is favoured by English Heritage, The Society for Protection of Ancient Buildings (SPAB) and local authority conservation officers. The Delta Membrane System itself doesn’t need any aggressive preparation therefore it will not create damage to historical or heritage structures. The Delta Membrane System is a reversible system, which can easily be removed at any time, retaining the structure underneath intact. The wooden nightclub floor was replaced with a concrete floor which has allowed for a fully serviceable perimeter drainage channel to be installed, discharging to a combination of passive and powered disposal points. An application of Koster Polysil TG 500 (an anti-lime coating/surface primer) was installed to reduce the risk of excess free lime leaching out of the concrete during the curing process. This free lime, if untreated, can enter the Cavity Drainage System which can impede the flow of water and cause sump pump failure. To seal the floors prior to finishes being applied Delta’s MS 20 flooring Cavity Drainage Membrane was installed. Case Study Results Cannon Clarke were able to design and install an ideal remedy for this listed building as the Delta MS 20 and MS 500 system is deemed ‘reversible’ satisfying local planning authority recommendations. The Delta System complies with BS 8102:2009 ‘Code of practice for protection of below ground structures against water from the ground’ and has an EN1350-1 Class E fire reaction classification. With a service life of over 100 years, this waterproofing solution will ensure the historic integrity of Bath’s vaults. The client was delighted with Cannon Clarke’s dedication to quality, authenticity and exceptional customer service.

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