Basement Flat, 1 Belmont, City Centre, Bath
1 Belmont forms part of an extensive terraced group of Grade II late 18th century houses at 1-20 Belmont, situated within the Bath conservation area and World Heritage site. The building occupies an end of terrace position on the corner of Hay Hill with an attractive single storey projecting entrance on the south elevation with coved niches and ornate pilasters flanking the central door.
The basement floor is indicated to have been in residential use from around 1995-1999 (see LB-2537-11 & LB-2537-10).
As part of the overall scheme of works to the lower ground floor flat, it is proposed to address ongoing issues with damp and water ingress. In places, previous inappropriate material works have been undertaken to install “injected DPC and plastered cement slurry system tanking”; the focus of these works appears to be the external north wall abutting Bedroom 2. The D&A Statement therefore proposes that “Where cement slurry system has been used in the past it is proposed to leave it intact and overlay with delta system, given the potential damage to the existing stone wall if cement slurry to be removed. It is proposed to use delta system.”
BPT acknowledges the difficulty of managing these poorly ventilated spaces, and we recognise that these may be susceptible to multiple forms of water ingress/damp, including run-off from the pavement above, which can be complex to address.
There do not appear to be signs of any significant material deterioration in the cement slurry used in Bedroom 2, although this is based on assessment of the photographs only and it is difficult to tell based on photographs alone without the benefit of the site visit. This is worth noting based on the relative difficulty of removing cementitious renders/slurries when these have not yet started to fail.
We have heritage concerns regarding the proposed retention of the existing cementitious layer under a delta membrane. The existing concrete render is likely responsible for exacerbating damp conditions and water retention in the vaults by trapping moisture within the walls and will continue to have a progressive impact on the condition of the historic stonework. Having said this, we also note that the use of an injected DPC would have a detrimental effect on the natural permeability of the stonework, but this measure is far more intrusive and irreversible. We maintain that the cited harm to the stonework resulting from the removal of the cement slurry should be considered against the ongoing damage to the stonework due to water retention and loss of ability to ‘breathe’; where possible, we encourage the removal of as much of this tanking as practicable to allow the space to dry out and then re-assess what damp mitigation works may be most appropriate to balancing the historic interest and “optimum viable use” of this basement flat.
We are further concerned that the proposed floor plan as provided on p.8 of the D&A Statement appears to indicate the proposed “injection of damp proof course and re-plastering” on a number of walls (highlighted green) including the rear external south wall and the external west wall of the lower ground floor lightwell. This is despite the fact that none of these walls are indicated in the existing plans (highlighted blue) to have already undergone damp proofing works. BPT remains strongly resistant to the use of cementitious tanking or injected damp proofing systems to listed buildings where this would directly inhibit the porous ‘breathable’ qualities of Bath stone and are frequently prone to failure whilst being incredibly difficult, if not impossible in the case of injection DPCs, to remove/reverse. No further mention is made to these proposed damp proofing works as part of this application, and as such we maintain that there is insufficient justification of the proposed harm to the special historic and architectural interest of a listed building. We strongly recommend that this aspect of the scheme is omitted and more sympathetic measures are considered to mitigate the effects of damp such as the application of a limewash or lime plaster of an appropriate sample and finish.
This application proposes inappropriate material alterations to a historic building without adequate justification contrary to the Planning (Listed Buildings and Conservation Areas), Section 16 of the NPPF, and Polices B1, BD1, B4 CP6, D1, D2, D3, and HE1 of the Core Strategy and Placemaking Plan and should therefore be refused or withdrawn.