Party Wall Notices for Rear Extensions: When Is a Notice Required?

Rectory Surveyors
2 days ago
5 min read

Party Wall Notices for Rear Extensions: When Is a Notice Required?

Rear extensions are among the most common residential building projects undertaken across London. Although the design may appear straightforward, the work can engage several provisions of the Party Wall etc. Act 1996.

An extension may involve building at the boundary, excavating beside a neighbouring property or carrying out work directly to an existing party wall. In some cases, more than one type of notice will be required.

Planning permission and Building Regulations approval do not remove the need to comply with the Act. These are separate statutory processes and must be considered independently.

Does Every Rear Extension Require a Party Wall Notice?

No. The need for notice depends upon the location, depth and construction of the proposed work and its relationship with neighbouring buildings and boundaries.

A notice may be required where the project includes:

• Building a wall at or astride the boundary

• Excavating below the level of a neighbouring building’s foundations within the relevant distance

• Cutting flashings, beams or other structural elements into a party wall

• Raising, thickening, rebuilding or otherwise altering a party wall

• Removing projections from a party wall or adjoining structure where the Act applies

The architectural drawings alone may not provide enough information. Foundation depths, structural connections and the position of existing walls must also be considered.

Building at the Boundary

Section 1 of the Act concerns new walls built at the line of junction between adjoining land. If the building owner proposes to construct a new wall astride the boundary, the adjoining owner’s written consent is required.

Without that consent, the building owner cannot use the Act to compel the adjoining owner to accept a wall built partly on their land. If consent is not provided, the building owner may usually build the wall wholly on their own land, subject to the design and other legal requirements.

A notice may also be required where a new wall is built wholly on the building owner’s land but directly up to the boundary. The precise location should be established before construction begins. An assumption based solely on the apparent position of a fence can cause serious difficulty if the fence does not follow the legal boundary.

Party wall surveyors do not have unrestricted jurisdiction to determine a disputed boundary. If the boundary position is genuinely uncertain, separate investigation and legal advice may be required.

Work to an Existing Party Wall

Section 2 applies to specified work undertaken directly to a party wall or party structure.

A rear extension may involve:

• Cutting flashings into the wall

• Cutting in beams or roof supports

• Raising the wall to enclose the extension

• Thickening, repairing or rebuilding it

• Exposing and weathering a previously enclosed part

• Removing projections where the statutory conditions are satisfied

These works can require notice even if everything is undertaken from the building owner’s side. Not every minor fixing into a shared wall is notifiable. The nature and consequences of the work must be considered. Structural work, substantial cutting or alteration of the wall is more likely to engage the Act than ordinary domestic fixings.

Excavating Near a Neighbouring Building

Section 6 can apply where excavation is proposed within three metres of a neighbouring building or structure and will extend below the level of the neighbour’s foundations. It can also apply within six metres where the proposed excavation meets the deeper test set out in the Act, assessed by reference to a 45-degree line drawn from the bottom of the neighbouring foundations. The neighbouring structure does not have to be a house. Garages, extensions and other qualifying structures may also need to be considered. An architect’s drawing showing the distance between the buildings does not establish whether the excavation will be deeper than the neighbouring foundations. The foundation information must be reviewed.

Why Foundation Depth Matters

Older London houses often have relatively shallow foundations, while a modern extension may require deeper concrete foundations because of current design requirements, ground conditions, nearby trees or the recommendations of a structural engineer. The new foundation may therefore extend below the neighbour’s foundation even where the properties are several metres apart. Where the neighbouring foundation depth is unknown, the project team may need to use available records, knowledge of the building’s age and construction or targeted investigation. Any assumption should be stated clearly and reviewed if different conditions are uncovered during excavation.

Planning Permission Is Not Party Wall Consent

Planning authorities consider matters such as design, scale, appearance and the effect of development upon neighbouring amenity. They do not determine compliance with the Party Wall etc. Act 1996. Building Control considers compliance with the Building Regulations. Approval does not constitute consent under the Act and does not resolve the statutory dispute between owners. Similarly, an adjoining owner’s planning objection or support does not replace their formal response to a Party Wall Notice. The Government’s explanatory booklet confirms that the Act operates separately from planning and Building Regulations procedures:

https://www.gov.uk/government/publications/preventing-and-resolving-disputes-in-relation-to-party-walls/the-party-wall-etc-act-1996-explanatory-booklet

When Should Notices Be Prepared?

Party wall matters should be considered before the intended construction date, not after the contractor has arrived on site. The statutory notice period depends upon the type of work. Notices concerning work to an existing party wall generally require two months, while notices relating to building at the line of junction or adjacent excavation generally require one month. The adjoining owner may agree to an earlier commencement, but is not required to do so. Sufficient drawings and structural information should accompany the notice where necessary to explain the work. Excavation notices require plans and sections showing the site and depth of the proposed excavation and whether underpinning or strengthening is proposed.

Late or incomplete notices can delay the project and increase professional costs.

What Happens After Notice Is Served?

The adjoining owner may consent, dissent and appoint a surveyor, or fail to respond. For notices under sections 2 and 6, a failure to respond within 14 days generally results in a deemed dispute. The statutory appointment procedure can then be followed. The owners may jointly appoint one Agreed Surveyor or each appoint a separate surveyor. The appointed surveyor or surveyors resolve matters within their jurisdiction and prepare a Party Wall Award regulating the notifiable work.

The adjoining owner cannot use the process simply to prevent lawful work. Equally, the building owner should not commence notifiable work merely because planning and Building Regulations approvals have been obtained.

Speak to the Neighbour Before Serving Notice

Early communication can reduce concern and make the statutory process more efficient. The building owner should explain the project, likely timing and protective measures before the formal documents arrive. Drawings should be sufficiently developed to answer reasonable questions. Informal discussions do not replace a required notice. Any consent must be properly recorded in writing.

Need Advice Regarding a Rear Extension or Party Wall Notice?

Rectory Surveyors Ltd advises building owners and adjoining owners regarding rear extensions, loft conversions, structural alterations and other work falling within the Party Wall etc. Act 1996. We can review the proposed drawings, advise whether the Act applies, prepare and serve the necessary notices and accept appointments where a dispute has arisen.

To learn more about our services, please visit:

https://www.rectorysurveyors.co.uk/services/party-wall-surveying-and-boundary-disputes