0405 Architecture · England · Guidance checked 20 October 2026

Possibly. An extension can require Party Wall etc. Act 1996 notices because of work to a shared wall, a new wall at the boundary, or excavation near a neighbouring building. Whether you need a surveyor’s award depends on the work and the response to the relevant notice. Start by establishing what the design actually involves.

For homeowners in Worcestershire and the West Midlands, the useful first step is a coordinated drawing showing the extension, neighbouring structures and proposed foundations. A friendly conversation matters, but it cannot fill gaps in that information.

Is a party wall agreement the same as planning permission?

No. Planning permission, Building Regulations approval and the party wall process are separate. This article concerns extension projects in England; the Act also applies in Wales. Source: GOV.UK, party walls overview.

Treat each as a separate item in your programme. Record who is dealing with it, what information they need and what must happen before the relevant work starts. A planning approval should prompt that review rather than close it.

Which parts of an extension need checking?

Check three situations: alterations to an existing party wall or structure; a new wall at the boundary; and nearby excavation. Cutting into a party wall for structural work can be relevant even where most of the extension stands on your land. Minor work such as ordinary shelving or replastering is generally different. Source: GOV.UK, work you must tell your neighbour about.

For excavation, distance alone is insufficient. Within 3 metres, compare the excavation depth with the neighbour’s foundations. Within 6 metres, a separate test concerns a line descending at 45 degrees from their foundation base towards the excavation. The detailed tests need a project-specific assessment. Source: government explanatory booklet, paragraph 28.

A detached house can therefore need a review. Equally, do not assume every trench within 6 metres automatically requires notice. Ask the designer and engineer what is known about the neighbouring foundations and how any uncertainty will be resolved.

What information makes the decision clearer?

0405 Architecture suggests using the following table to brief the design team and a party wall surveyor where needed. It is a coordination checklist, not a statutory test or a substitute for specialist advice.

Proposed work	Information to assemble	Question to resolve
Beam near a shared wall	Existing wall arrangement and proposed beam support detail	Will the work cut into or otherwise affect the party structure?
Extension wall at the boundary	Survey, ownership information and wall section	Where will the wall, foundations and roof edge sit?
New foundations near next door	Dimensioned plan and excavation section	What are the relative distances and foundation depths?
Drainage trench beside a building	Drain route, trench depth and adjacent structures	Does excavation need assessment alongside the main foundations?
Uncertain boundary position	Relevant title documents and survey evidence	Is separate boundary advice needed before fixing the design?
Later structural redesign	Revised drawings with changes clearly marked	Does the notice or agreed information need reviewing?

Begin with a plan, then add a section through the tightest relationship. Show the proposed excavation rather than only the finished wall. Record uncertain information explicitly: an assumed foundation depth should not look like a surveyed fact.

Ask who will arrange any necessary investigation and how it will be carried out safely and lawfully. Do not ask the builder to discover the neighbour’s foundations informally while digging the main works.

Notice, consent and award: what is the difference?

A notice formally describes relevant proposed work. Consent is the adjoining owner’s written agreement. A party wall award is the document made by the appointed surveyor or surveyors when resolving a dispute; it sets out the work and how and when it is carried out. Source: GOV.UK, if you cannot agree.

For existing party-structure work and qualifying excavation, no written consent within 14 days means a dispute is deemed to arise. New boundary walls have different provisions; do not apply that rule indiscriminately to every notice. Source: government explanatory booklet, paragraphs 49–51.

A quiet neighbour is not evidence of consent. Keep written responses with the relevant notice and drawing revision. Source: GOV.UK, reaching agreement.

How early should this be addressed?

Typical minimum notice periods differ: two months for party-structure work, and one month for line-of-junction work or qualifying excavation. Earlier commencement needs the adjoining owner’s written agreement. Source: government explanatory booklet, notice guidance.

Those periods are not a promise that every issue will be resolved within that time. Build the review into design development, before committing to a start date. Identify all relevant owners: a property may have more than one qualifying owner. Source: government explanatory booklet, introduction.

Tell your neighbour what you hope to achieve while the proposal is understandable and still open to considered adjustment. Share a clear drawing and explain which technical details remain under development. Keep that discussion separate from asking for a formal response.

Can changing the design help?

It may change the issues that need assessment. Compare options with your architect and engineer before choosing one solely to avoid paperwork. Moving a wall, changing beam supports or revising foundations can affect the room, structure, cost and construction sequence.

For example, compare the usable kitchen width and roof junction for two wall positions. Show how each option would be built and maintained. This is a suggested design exercise, not a claim that a particular offset removes the Act’s requirements.

Once an option is selected, keep the architectural drawings, structural details and notice information aligned. If the engineer changes the foundation proposal, flag the change before excavation. A small revision on one drawing can alter the question the neighbour was originally asked.

What does the party wall process leave unresolved?

The Act does not settle a disputed boundary line. Resolve uncertainty through appropriate separate advice. Source: government explanatory booklet, paragraph 43.

Keep a separate list of other project constraints, including drainage, access arrangements and outstanding approvals. Our guide to building an extension over a drain or sewer explains another issue to investigate before fixing the layout.

Planning an extension close to your neighbour?

Send 0405 Architecture your property location, available drawings, photographs of the boundary and intended start date. Explain whether structural details or notices already exist. We can discuss a scope and fee for extension design and technical coordination, with specialist party wall advice separately identified where needed.

Our residential and technical design services can help turn those constraints into a coordinated proposal, according to the agreed appointment.

0405 Architecture is a RIBA Chartered Practice based in Kidderminster, Worcestershire. Its legal entity is 04/05 Architecture Limited.