21 Dafford Street, Larkhall, Bath

21 Dafford Street forms part of a Grade II early to mid-19th century terrace situated in the Bath conservation area and World Heritage Site. The terrace is made up of modest two-storey double-depth houses stepped down the west-east slope in pairs. There is a mix of window types used along the terrace, with the majority of dwellings having replaced a traditional 6-over-6 sash profile with a Victorian 1-over-1 sash profile. 21 Dafford Street has similarly had its windows replaced with 1-over-1 single glazed sashes, in an aluminium frame which is of detriment to the appearance and material vernacular of the listed building and the group value of the terrace. It has additionally had its traditional 6-pane timber door removed, examples of which are still common across the terrace, and replaced with a Victorian-style alternative.

BPT previously responded to application 21/01422/LBA; we were supportive of the principle of slimlite double glazing pending clarification of further design and specification details.

We continue to be strongly supportive of the opportunity for the installation of slimlite double glazing and associated thermal improvements with no loss of historic fabric. The replacement of the existing anachronistic aluminium sash windows with timber equivalents would help to reinstate the traditional material appearance and integrity of the listed building, with additional heritage gain to the group value and appearance of the Grade II terrace.

We note alterations to the scheme have addressed our previous comments, including a proposed angled meeting rail of a reduced thickness, and alterations to change the proposed glazing bar to an ovolo profile.

However, the sash window fenestration pattern has now been amended to propose a 2-over-2 sash window, rather than the previously proposed 6-over-6 fenestration. The original fenestration of the terrace has largely been lost, with the prevalent replacement style being single pane sashes that were introduced from the mid-19th century onwards. Considering the early 19th century date attributed to the terrace, a 6-over-6 sash window design would therefore be more typical and examples of this window form were retained along the terrace until at least 1973. There is no indication as part of this application as to the historic reference for the proposed 2-over-2 sash windows, which are likely a design of a later date as glazing panes could be manufactured in larger sizes.

Whilst we are supportive of the principle of the scheme, we therefore maintain a preference for a traditional 6-over-6 sash profile in this building. We consider there is a positive opportunity to reinstate a window profile traditional to the terrace, which has now been all but lost.

We maintain that we are interested in working with the applicant to monitor the performance of the windows before and after retrofit. BPT is currently seeking positive examples of energy efficiency retrofit in traditional and listed homes to create case studies that can then inform future works in Bath’s historic housing stock.