Party Wall Agreements and Plumbing Work in London: What Owners Need to Know

When the Party Wall Act Applies to Plumbing Work in London

The Party Wall etc Act 1996 applies to three categories of work: works to an existing party wall or party structure, the construction of a new wall on or at the boundary of two properties, and excavations within three metres of an adjoining owner property where the excavations will be deeper than the foundations of the adjoining property, or within six metres where the excavation will intersect a line drawn at 45 degrees from the base of the adjoining property foundations. For plumbing work in London, the most common trigger for the Party Wall Act is excavation for new drain runs, inspection chambers, or connection points that are within the proximity thresholds defined by the Act. In London terraced and semi-detached properties where houses are built close together on narrow plots, these thresholds are regularly triggered by drainage works that are only a short distance from the boundary.

Works to shared or party drain runs are also a potential trigger for the Act where the drain passes through or beneath a party wall. In older London properties, it is common for the foul drain from a terrace of houses to run as a combined drain beneath the rear gardens, passing through each plot in turn before connecting to the public sewer at the end of the terrace. Works to this shared drain, including relining, excavation for repairs, or modifications to the drain route, may constitute works to a party structure if the drain passes through a wall or structure shared with an adjoining property. A drainage survey to establish the exact route and construction of the drain system is advisable before any works are planned on a shared or potentially shared drain run in a London terrace.

Serving Party Wall Notices for London Plumbing Projects

When a London plumbing or drainage project triggers Party Wall Act obligations, the building owner must serve the appropriate notice on all adjoining owners before commencing the works. The notice period is one month for works directly to a party wall or party structure, and two months for excavation works near an adjoining property. The adjoining owner has 14 days to respond, and if they do not respond in writing or if they dissent from the proposed works, a dispute is deemed to have arisen and one or two party wall surveyors must be appointed to agree an award that governs how the works are to be carried out. The award will typically include provisions for the protection of the adjoining property during the works, a schedule of condition recording the state of the adjoining property before works commence, and requirements for making good any damage caused.

In practice, the majority of London Party Wall Act notices served in connection with plumbing and drainage projects are met with written consent from the adjoining owner, particularly where the works are straightforward and the building owner has explained the nature of the works clearly in advance. However, obtaining consent requires that the notice has been properly served and that the adjoining owner has had the full notice period to consider the proposal. A building owner who commences notifiable works without serving the required notice cannot retrospectively satisfy the Act, and an adjoining owner who discovers that notifiable works have commenced without notice can apply for an injunction requiring the works to stop until the party wall process has been followed. Prestige Engineers can advise London property owners on whether their proposed drainage or plumbing projects trigger Party Wall Act obligations and can recommend party wall surveyors when the notice and award process needs to be followed.