Basement, 5 Camden Crescent, Lansdown, Bath

5 Camden Crescent is a Grade II listed late 18th century terraced townhouse, since converted internally into flats, situated within the Bath City-Wide Conservation Area and World Heritage Site. It immediately adjoins the southernmost dwelling of the Grade I section of the late 18th century terraced crescent curving round towards the north across Nos. 6-21. Its neighbouring properties at Nos. 1-4 are also Grade II listed due to a simpler elevational treatment and stepped setback from the homogenous articulation of the central crescent intended to read as a single building.

The proposed focus of works is internal at basement and sub-basement level within No. 5. It is indicated that the property was previously granted consent for works to the basement and sub-basement, including the use of an injected DPC and a Vandex waterproofing treatment to the vaults (see application 98/00347/LBA). The existing tanking treatments in situ at the property are indicated by the applicant to align with previous consent, though in places it is summarised that the tanking is now failing. However, there are areas indicated to be new or later applications of tanking, potentially to address ongoing failure of the earlier system, which would not be considered to fall within the original consent – see where this is illustrated in detail of the photographs submitted of Vaults 01 & 02.

BPT maintains that the previous application of a cementitious slurry does not adequately justify continued use of this material treatment where it has been demonstrated to be of significant detriment to historic fabric, and in some cases results in irreversible damage. Any further waterproofing applications or repairs should not be carried out without first securing appropriate consent.

Whilst we recognise that the original waterproofing system has been in place since the 1998 consent, BPT expresses a strong preference against the use of cement-based waterproofing works where this would be incompatible with historic fabric and harmful to the special interest of a listed building. Where possible, we encourage consideration of its removal to allow the underlying stonework to breathe, though the feasibility of removal must be appropriately balanced against the resulting harm to stonework that would be caused by removal works. In the planning balance, it may therefore be considered that there would be greater harm to historic fabric from the cement slurry’s removal, which may therefore justify its retention, though we consider that the newest layers of cement waterproofing should not be considered to be authorised as part of this application.

We are supportive of the opportunity to remove harmful tanking works wherever this opportunity presents itself, in the case where the tanking layers are starting to fail (see proposed works to the rear vaults). Where several options have been proposed for finishing the rear vaults, either a membrane lining or application of a limewash over the original stonework, we express a strong preference for the latter where this would be more compatible with the material qualities of historic fabric and allow the texture of the original interior finish of the historic vaults to be legible, where limewash typically offers a thinner, more translucent finish. At this stage, it is unclear as to whether the conditions of the vault would justify the need for a waterproofing membrane, or whether existing damp levels would be sufficiently managed through the use of a limewash. We therefore encourage the failed render to be removed to allow the natural stone surface to be restored, and where necessary to dry out, and then re-assess what damp mitigation works may be most appropriate.