2 Alice Park, Gloucester Road, Lower Swainswick, Bath

2 Alice Park forms one half of a pair of Grade II listed 1930s-1940s cottages associated with park keeper of Alice Park, situated within the Bath conservation area and World Heritage Site.

We encourage further provision of information regarding the type of cavity insulation to be used and how it may function with the porous, ‘breathable’ properties of the Bath stone external wall (although it remains unclear as to whether the internal wall of the cavity wall system is also in a matching Bath stone). When considering insulation of a historic building, potential insulation solutions should be considered with regards to how they facilitate the natural properties of historic fabric and continue to allow these to ‘breathe’ without exacerbating potential issues with water ingress or water retention resulting in damp. We recommend any works are undertaken by a heritage accredited professional, or a professional with relevant experience of working with listed and traditional-construction buildings.

It is indicated that cavity wall insulation of an unspecified type has already been installed at 1 Alice Park. It would therefore be helpful to further assess the existing condition of this property to see whether there has been any adverse impact resulting from this type of insulation, which may then be used to inform the best practical approach to the adjoining property.

We also recommend that further information is required regarding the ‘plugging works’ following installation of the cavity insulation. Typically, this type of insulation is installed via a large number of plug holes in the external walls. It is proposed that these would be infilled “with material from the drilling such that the colour and texture of the filled holes will match the original stone”; however, in many cases the outline of the plug holes may still be visible upon completion with cumulative detriment to the appearance of the building. We therefore recommend that the methodology of the proposed remediation works following installation is included to ensure that the external works to the building are completed to a high standard. In Historic England’s guidance on Insulating Early Cavity Walls, it is recommended that “it may be preferable to take out bricks or stones and then replace on completion.”