Top Flat, 21 Henrietta Street, Bathwick, Bath

21 Henrietta Street forms part of a terraced group of Grade I listed late 18th century townhouses at 20-35 Henrietta Street, situated within the Bath City-Wide Conservation Area and World Heritage Site.

As existing, the roofscape is indicated to have been refinished in fibrous cement slates, and as such a traditional, historic material roof treatment has not been retained. The inner roof slope is also described as having the same treatment, though it appears in photographs the cement slates seek to mimic the colour and style of clay pantiles seen elsewhere along the terrace.

We recognise the urgency of the existing condition of the property with the collapse of the mansard roof beam over the rear dormer window and resulting damage to the building’s roof structure and water ingress. Suitable repair works are encouraged as soon as possible to prevent further damage and restore the top flat to a liveable condition.

Works are further proposed for the re-finishing of the external rear mansard roof slope in “new Redland interlocking Cambrian slate grey pre-weathered” to replace the existing fibrous cement slates. We are generally supportive for the replacement of an unsympathetic, non-historic roof surface where this offers an opportunity to reinstate a more traditional and sympathetic material finish that would enhance the character and appearance of a listed building. There would be some limited visibility of the rear roof slope from Henrietta Park, though this is partially screened by established planting and surrounding trees.

We recognise that where the existing roof finish is already an artificial, modern addition, this intervention has already resulted in less than substantial harm and any further works would have a very limited impact on historic fabric. Nonetheless, given the Grade I status of the building and its contextual relationship with its built setting, we maintain that the use of a reconstituted slate would be inauthentic, visually inappropriate, and would fail to sustain the special historic and architectural interest of the listed building. Reconstituted slate is not an acceptable alternative to natural slate and remains visually discordant in comparison to natural slate in its thickness, finish, and how it weathers. Approval of this material would individually and collectively compromise the authenticity of the historic environment.

We maintain that the opportunity should be taken to reinstate a materially coherent roof surface to the Grade I listed building, with the use of a natural Welsh slate being the traditionally appropriate local material which would sustain the historic and architectural significance of not only the building, but the Conservation Area and World Heritage Site setting. Given the relatively limited size of the roof slope to be re-surfaced, options for the use of reclaimed slate may also be available.

At this stage, the priority is to address the collapsed mansard beam and restore the structural integrity of the roof, which we maintain should be facilitated as soon as possible to prevent further material harm to a listed building. However, we are currently unable to support the proposed material roof finish and strongly encourage other options to be explored further.

This application proposes the use of inappropriate materials which would harm the architectural interest and significance of the Grade I listed building, would neither preserve nor enhance the character or appearance of the Conservation Area, and risks cumulative harm to the OUV of the World Heritage Site. This application is therefore contrary to the Planning (Listed Buildings and Conservation Areas) Act 1990, Section 16 of the NPPF, and Policies B1, B4, BD1, CP6, D1, D2, D3, and HE1 of the Core Strategy and Placemaking Plan.