1A Oak Street, Westmoreland, Bath
1A Oak Street forms part of a Grade II early 19th century terrace of residential dwellings, situated within the Bath World Heritage Site and the immediate townscape setting of the Bath conservation area. The terrace is modest in scale and form at two storeys with a two bay frontage in Bath stone ashlar, stepping down the slight south-north slope towards Lower Bristol Road. The terrace as a whole encompasses two ‘halves’ - 1A, 1-5 & 33-38 Oak Street, and 20-28 Oak Street – which were bisected by the introduction of the St James Viaduct, now Grade II*, in 1840. This application forms part of a wider scheme that encompasses 23 and 25 Oak Street, also Grade II listed.
There is a lapsed permission for the works as proposed (see application 18/04736/LBA).
BPT is strongly supportive of the proposed replacement of the existing, non-historic sash windows. These are aluminium-framed and as such are of negligible material or historic interest. Their replacement with timber-framed sash windows would be more materially in-keeping with the appearance and integrity of the listed building, and would enhance the grouped appearance and cumulative significance of the terrace.
In light of the Climate Emergency, BPT is supportive of sensitive sustainability retrofits, where deemed appropriate, within the historic environment, as well as the sympathetic upgrade of traditional housing stock to better meet modern standards of living. As such, we therefore note a positive opportunity for the sensitive implementation of energy efficiency retrofits and thermal improvements without the loss of historic fabric.
We have previously encouraged the consideration of slimlite double glazing at 36 Oak Street (see application 19/03755/FUL).
In this particular case we recognise this proposal would result in less than substantial harm and no loss of historic fabric. We note the associated heritage gains of the use of a more traditional sash window and the improved thermal performance of the proposed windows.
We note that the extant window treatment along the terrace is varied, with a number of fenestration types present such as single pane sashes as well as multi-pane designs including 2-over-2 and 6-over-6 sash windows. Therefore, whilst it may be considered that there is some scope for the type of window articulation selected as a replacement without being of direct harm to the appearance of the terrace, there could be an opportunity to reinstate a 6-over-6 sash style which would have likely been used along the terrace at the date of its construction.
Whilst supportive of the principle of this scheme, we therefore maintain a preference for 6-over-6 timber sash windows to reinstate the historic appearance of the terrace, and match other existing examples along Oak Street.
We note that the proposed glazing bar is as previously proposed under application 18/04736/LBA and was described as a lamb’s tongue profile. However, as part of this application there is no reference to existing glazing bar profiles or styles as existing along the terrace. We recommend that the proposed design reference for the replacement window profile is clarified with reference to the listed building’s wider context and shared group value as part of the terrace. This could be an opportunity to reinstate a historically-evidenced profile, or reinforce a prominent glazing profile type already present.
BPT is very interested in working with the applicant to reach an acceptable solution and to assess the performance of the windows before and after retrofit to create a ‘best practice’ case study. This application, as part of a group of applications for the upgrade of a number of listed properties along Oak Street, could help provide an invaluable opportunity to monitor the thermal and acoustic efficiency of the windows, before and after, whilst also observing any additional repercussions such as changes in humidity levels. This information could then be used to more accurately assess the suitability of slimlite installation in Bath’s historic building stock, and inform future upgrades of listed buildings.