Serving Party Wall Notices in London: When, What to Send and How the Process Works

The Act covers three categories of work:

Section 1 — New wall on the boundary line (Line of Junction): building a new wall on or astride the boundary between two properties (for example, a new boundary wall or the wall of a new outbuilding on the boundary line).

Section 2 — Party wall works: works to an existing party wall (the shared wall between two properties). This includes:

• Cutting into or removing the party wall
• Increasing the height or thickness of the party wall
• Demolishing or rebuilding the party wall
• Inserting a damp-proof course through a party wall
• Underpinning a party wall
• Structural work to a chimney breast on the party wall

Section 6 — Excavation near the boundary: excavation within 3 metres of an adjoining building (where the excavation goes below the bottom of the foundations of the adjoining building), or within 6 metres where excavation meets a 45-degree plane drawn from the base of the adjoining foundation.

Most relevant for London home projects:

• Rear extensions (if they touch or are within 3 metres of the party wall or boundary)
• Loft conversions (if structural work is being done to the party wall at roof level, e.g. forming a new party wall above the ridge, steel on the party wall)
• Basement or below-ground excavation within 3 or 6 metres of the adjoining property's foundations
• Chimney breast removal on the party wall

Section 1 Notice (Line of Junction): served at least 1 month before starting work. The neighbour can agree or dissent. If they agree, the work can proceed as agreed. If they dissent, a party wall award is produced.

Section 3 Notice (Party Structures Notice): served at least 2 months before the planned commencement date for Section 2 party wall works. The notice must specify the works proposed. The neighbour has 14 days to respond. Silence (no response) counts as dissent.

Section 6 Notice (Excavation Notice): served at least 1 month before starting excavation works that fall within the Section 6 categories. Must specify the excavation proposed.

A valid party wall notice must include:

• The building owner's name and address
• The address of the affected property
• A description of the proposed works
• A proposed start date
• Be signed by the building owner (or their agent)

Model form notices are available from the Ministry of Housing, Communities and Local Government and from party wall surveyor associations. Notices can be served by recorded delivery, personal service, or through the Planning Portal in some cases.

If the adjoining owner consents (within 14 days): works can proceed as proposed. A Schedule of Condition of the adjoining property before works start is strongly recommended (though not legally required where consent has been given — it protects both parties in case of damage claims).

If the adjoining owner dissents (or does not respond within 14 days): both parties must appoint surveyors (or agree a single agreed surveyor). The surveyors produce a party wall award setting out the conditions under which work may proceed, the obligations of the building owner, and providing for making good any damage.

If the adjoining owner is unreachable: the Act provides for this — the building owner can proceed via the surveyor process even where the neighbour cannot be located, after demonstrating reasonable attempts to serve notice.

Notice must be served sufficiently in advance of the start date. Common errors include serving notice too late (notices must be served at least 1 month or 2 months before the start date, depending on the type of work) or trying to start works before the 14-day consent period has expired.

For a typical rear extension starting in April: Section 3 notice must be served no later than early February (2 months before). If the programme is tight, serve notice as early as possible.

See the separate guide to party wall surveyors for information on appointing surveyors, the award process, and typical costs.