19 Sion Hill, Lansdown, Bath

19 Sion Hill is a Grade II early 19th century townhouse situated within the Bath conservation area and World Heritage Site. It immediately adjoins the Grade II late 18th century dwelling at 18 Sion Hill, and forms the wider, indicative streetscape setting for a number of Grade II late 18th and early 19th century detached and terraced dwellings along Sion Hill.

We emphasise that BPT is not supportive of the principle of unauthorised works to listed buildings without first securing the appropriate planning consent.

We maintain strong concerns with the proposed, retrospective works to apply a “waterproofing compound” to the southern retaining wall of the vault. A “15mm integral styrene butadiene resin structural waterproofing system” is proposed; this appears to be a liquid waterproofing treatment although further material specifications as to the mix and type of the system in use is strongly recommended. BPT maintains an in-principle resistance to the use of cementitious or ‘slurry’ tanking within historic buildings. The use of impermeable, cement-based systems is not compatible with the traditionally porous qualities of historic building materials such as Bath stone and would impact the building’s ability to ‘breathe’, causing more serious long-term issues and damage. The use of a liquid system would result in irreversible harm to historic fabric and would be very difficult to remove from stonework at a later date.

We maintain that Bath’s historic vaults and basements are attributed particular evidential and historic significance as areas where their distinctive, frowsty character is frequently sustained with limited later intervention. There is limited information provided as to their existing character and appearance prior to works (although it is indicated that the walls were already plastered) against which to assess the proposed changes.

Furthermore, we do not consider that the proposed interventions are appropriately justified when the D&A Statement indicates that water ingress issues experienced at basement level were largely attributable to the failed seal to the pavement skylight. Repairs to the skylight should therefore be adequate to mitigate further water ingress and there is subsequently no reason for the use of far more materially intrusive measures.

This application would therefore fail to sustain the special interest of a listed building, contrary to the Planning (Listed Buildings and Conservation Areas) Act 1990, Section 16 of the NPPF, and Policies B1, BD1, CP6, D1, D2, D3, and HE1 of the Core Strategy and Placemaking Plan and should be refused or withdrawn.