Removal of uPVC windows and doors to the main house and replace with traditional timber windows. Replace uPVC bay windows with Crittall windows. Provision of external wall insulation to a…
Our Response

The Towers is an unlisted, late 19th/early 20th century semi-detached residential dwelling, situated within the Bath City-Wide Conservation Area and World Heritage Site. It forms one half of a pair with the adjoining residence at The Glen, although these may have originally been part of a single detached dwelling that was subdivided later in the 20th century. The Towers forms a clearly-visible aspect of the Entry Hill streetscape, particularly in short to mid-range views from the northern approach. It retains some visual and architectural interest due to its variation from the standard pitched roof form of the surrounding townscape, utilising a crenellated parapet (likely on the tail-end of the Gothic Revival movement). The building has been subject to significant later alterations, including the removal of the southern ‘wing’ in the late 20th century and associated alterations to the eastern, street-facing façade.

In response to the Climate Emergency, BPT is supportive of the principle of retrofit works to improve the energy efficiency and thermal performance of Bath’s existing building stock, where this does not result in adverse impact to the character and appearance of the conservation area.

We emphasise the importance of finding solutions to make improvements to Bath’s existing housing stock, where reuse and retrofit remains a more sustainable solution than new construction, as well as securing functional future for traditional and unlisted buildings.

We are supportive of the proposed replacement of the existing uPVC windows with timber-framed sash windows, which would be generally more in keeping with the age and character of the building, and the visual amenity value of the conservation area. Whilst not specified as part of the application, we encourage the replacement windows to be timber double glazed/slimlite double glazed to improve both the appearance and thermal efficiency of the building.

The D&A Statement indicates that “the southern elevation of this area has been rendered, possibly to combat damp issues in the loft space”, but this area of render is not indicated on the existing/survey elevations. The photos of the building as provided within the application indicate the existing use of Bath stone ashlar across the east and south elevations, though the stone appears newer where the southern ‘wing’ has been removed.

The building is indicated to suffer from damp and condensation issues in the eastern wing, where “the walls are only a single skin of solid stone thick, less than 200mm.” We are therefore supportive of proposals that seek to improve the liveable standards of this housing type and subsequently ensure its continued occupation, whilst considering the natural qualities and ‘breathability’ of porous Bath stone and the need for a compatible intervention.

It is proposed to install a “breathable” external wall insulation, finished with a lime render. This would result in some visual impact where the existing east and south Bath stone elevations would be obscured by an overlaid insulation product and render finish. BPT has concerns regarding the use of render across principal or high-visibility elevations within the conservation area, where the colour and finish of a render typically results in an over-bright and jarring appearance in a heritage context, against the weathered Bath stone palette. Whilst we recognise the cited public benefits of the scheme to improve the thermal performance of a dwelling, its overall energy efficiency, mitigate ongoing damp issues, along with sustaining occupation and maintenance, this should be appropriately weighed against the change to the character of the street scene and townscape and if the degree of visibility and quality of views of the building within its wider streetscape setting amounts to any degree of harm, or adverse effect to the character of the local area.

Furthermore, the planning application process provides an opportunity for the consideration of why this approach to insulation has been selected in relation to the behavioural properties of this traditional building (ie. solid external walls in porous stone) and the appearance and character of the context. And why other options such as internal insulation; have been discounted as unviable or less effective. These details should be included as part of the overall design journey and justification for the proposals.  

In this instance the visual impact, whether the change in material appearance preserves or enhances the conservation area and degree of harm would be dependent on the proposed render mix, colour, and finish, which we strongly recommend are provided as part of the application and the decision-making process. The use of a lime render may help to soften the appearance of this intervention where an appropriately textured finish and colour are selected to better match the material palette of the streetscape.

It is important to ensure a well-detailed finish to minimise risks such as cold bridging at external corners of the building, as well as how the proposed render system would relate to window/door openings. For instance, the intersection of the external render system with the east elevation of The Glen, whilst providing a neat junction between properties, would require the relocation of the rainwater pipe and may intrude on the existing first floor window opening, depending on the proposed insulation thickness. The insulation system is also indicated to cover the crenellated parapet, which would be difficult to appropriately finish to match this detail. A rendered finish in this area would be more prone to staining in the absence of any drip or stringcourse above. It may be more appropriate to use the stone stringcourse as a cut-off point for the proposed insulation system, although the practicalities of this are dependent on the projection of the string course, the height of the parapet and whether the first floor ceiling extends above the string course.

We recommend that additional evidence of the carbon saving results of installing similar insulation systems on traditional stone (solid wall) homes elsewhere should be provided for comparison and to appropriately understand the public benefits as part of the planning balance.

Application Number: 23/00700/FUL
Application Date: 21/02/2023
Closing Date: 30/03/2023
Address: The Towers, Entry Hill, Lyncombe, Bath
Our Submission Status: Comment