Internal alterations for regularization of unauthorized tanking works to basement vaults. Replacement of Vandex tanking system with Delta membrane system.
Our Response

4 & 5 North Parade are two individually-listed Grade II* mid-18th century terraced townhouses designed by John Wood the Elder, situated in the city core of the Bath conservation area and World Heritage Site. They present a dual, uniform façade in Bath stone ashlar with retained Georgian-style six-over-six single glazed sash windows. Both buildings currently operate as offices, but retain a minimal, unobtrusive approach to commercial advertisement on the ground floor. It forms part of the wider terrace with the Grade II* mid-18th century premises of the Abbey Hotel, also attributed to John Wood the Elder. 4 & 5 North Parade forms the wider townscape setting of a high concentration of Grade II terraced buildings, and immediately overlooks the Grade II Parade Gardens to the north-east.

The focus of this application is on the unusual subterranean vaults that connect the buildings with the Grade II Parade Gardens, public gardens established from the beginning of the 18th century and consolidated as Orange Grove in 1734. The vaults form part of the layered levels of the city, setting North Parade up and back from the river but these allowed for privatised access to the sunken Parade Gardens, level with the river edge. Unusually, the vaults are indicated to have had a more direct residential function to allow residents to move from the houses to the gardens through an interconnected series of vaults accessed via the basement. Examples of doorways remain in the northern retaining wall with glazed fanlights, indicating a more polite function and likely immediate use by residents rather than servants. From the existing plans, the vaults of 4-5 North Parade appear to retain a connecting door to the gardens via a later 1930s link.

Vault 4 has been lined with a failed “Vandex render treatment”, although this more likely refers to a cementitious waterproofing slurry. Vaults 5 and 6 have been lined with a Delta membrane which has partially failed.

We note that the Heritage Statement has been commissioned to provide a historic overview of the vaults at 4-5 North Parade and the Abbey Hotel. We therefore refer to application 21/04188/LBA where we have already submitted comments also relevant to this application, but amend our comments as follows to account for the slight variation in proposed works:

We maintain our opposition to works to listed buildings that go ahead without first securing the appropriate listed building consent.
In principle, we object to the use of cementitious tanking within historic buildings. These impermeable materials do not allow the permeable traditional building fabric to breath or moisture to pass through; thus, moisture is displaced or trapped and frequently this can lead to problems elsewhere. In addition, these approaches have a short life span and are known to fail over the passage of time, but can result in irreversible damage to historic fabric when removed. We are therefore supportive of the proposed removal of the Vandex system, where possible, to prevent further detrimental harm to historic fabric.

We are concerned regarding proposals to “locally [strip] back [the Delta membrane] where defective and [repair it]” with the implied retention of the majority of the unpermitted membrane in situ. It is unclear as to how the membrane can be effectively and sustainably patch repaired without undermining its long term performance. The D&A Statement sites that there has been damage to the original hydraulic lime capping due to invasive overhead service works, and there has been an inspection of ongoing water penetration through the vault crown in Vault 3 as reported in the Heritage Statement. However, this is assumed to be the case throughout all of the vaults without further relevant investigation works. We therefore do not consider that the works as proposed have been fully justified or clearly evidenced in relation to the high significance of an unusual historic structure and part of a pair of Grade II* listed buildings.

We continue to strongly recommend that all unpermitted insertions are removed as part of this application to best reverse the harm that has already been caused. An assessment of the vault stonework across Vaults 4, 5, and 6, once uncovered, is required to fully comprehend the extent of the reportedly ongoing water ingress, the current condition of historic fabric, and consequently justify the fitting of a new cavity membrane system.

There is some evidence provided within the Heritage Statement of the fitting of dados and matchboarding, as well as plastering over of stonework, pre-1940s. Due to the unusual, residential associations of these vaults as access to the gardens, it may be considered that a similar internal decorative treatment may be considered acceptable, albeit it remains unclear as to the extent of this type of treatment and does not consider the possibility of a dual service use in vaults set back from the main through route to the gardens (Vault 4?). Figure 21 directly references the removal of plaster from the basement “front room”, which includes a window, and the “back room”, which suggests a more polite room treatment on those vaults directly adjacent to, and accessible from, Parade Gardens.

We suggest further information is provided regarding the full extent of the proposed fitting of matchboarding and the reasons for doing so. From the photos provided the vaults appear to serve a storage/service use in relation to the main building, soon to be converted to hotel use following a recent grant of planning permission (see 21/00879/FUL) We maintain some concerns that possible aesthetic reasons for the proposed fitting works could indicate an intention for the habitable use of the vaults. Whilst these vaults may have had a more directly residential or polite function historically, exacerbation of conditions such as increased water ingress and poor ventilation mean that the vaults are no longer suitable for this type of use. A more immediate use, such as creation of bedrooms or amenity spaces for guests as part of the anticipated change of use, would place the vaults under increased pressure for further invasive measures to manage the damp conditions, with further harm to the special architectural and historic interest of a listed building.

Application Number: 21/04215/LBA
Application Date: 14/09/2021
Closing Date: 15/10/2021
Address: 4 North Parade, City Centre, Bath
Our Submission Status: Comment