100+ five-star reviews · FPWS & RPSA members · London & the Home Counties
Rear extension project guide
Planning a rear extension? We’ll help establish whether Party Wall Notices are required for boundary walls, excavations or work affecting a shared structure.
Party Wall considerations
The Party Wall Act is often relevant to rear extensions because new foundations are frequently excavated close to neighbouring buildings.
The position depends on factors including the distance between the excavation and neighbouring structures, the relative foundation depths and whether new construction is proposed at the boundary.
Excavation close to a neighbouring structure can fall within Section 6 where the proposed excavation will extend deeper than the neighbour’s foundations.
Some deeper excavations can fall within the 6 metre provisions, depending on the depth and geometry of the proposed excavation relative to neighbouring foundations.
A new wall proposed on or at the Line of Junction can involve Section 1 of the Act.
Foundation design, depth and any projection beyond the boundary can affect the Party Wall position and should be considered before work starts.
Do I need a Notice?
Many rear extensions require at least one Party Wall Notice, but not every extension does.
The answer depends on the proposed foundations, neighbouring buildings, boundary position and the design of the works.
The Party Wall process
We review the proposed works and identify the relevant Party Wall requirements.
Where required, the appropriate Party Wall Notices are prepared and served.
The next stage depends on the adjoining owner’s response.
Two possible routes from here
Route A — If they consent
The adjoining owner consents to the Notice.
The neighbouring property can be inspected and recorded before the relevant works begin.
The relevant works can proceed subject to the wider requirements of the project.
Route B — If they dissent
A Party Wall dispute arises for the purposes of the Act.
The owners appoint an Agreed Surveyor or separate surveyors.
The neighbouring property is inspected and recorded where appropriate.
The surveyor(s) agree and serve the Party Wall Award dealing with the notifiable works.
The relevant works can proceed in accordance with the Award and wider requirements of the project.
How we help
One dedicated surveyor reviews your plans and stays your point of contact throughout.
The Party Wall route
If the Act applies, we’ll identify and serve the appropriate Notices for the proposed works.
Learn about Party Wall NoticesThe Party Wall process may remain relatively straightforward.
A Schedule of Condition can also be arranged where appropriate.
Surveyor appointment(s) are required and the matter can progress towards a Party Wall Award.
Tell us about your project and we’ll confirm which route applies.
Already have drawings?
Architectural drawings are usually enough for an initial review. Structural information can also be provided where available.
Frequently asked questions
General guidance only. Whether the Act applies depends on the drawings and the position of neighbouring buildings.
No. Many do, because of excavation close to neighbouring buildings or work at the boundary, but an extension well away from neighbouring structures and the boundary may not involve notifiable work.
Under Section 6, excavation within 3 metres of a neighbouring building or structure can be notifiable where it will extend deeper than the bottom of the neighbour’s foundations.
Within 6 metres, excavation can be notifiable where it would cut a line drawn downwards at 45 degrees from the bottom of the neighbour’s foundations. It is more commonly relevant to deeper foundations.
The relative depth of your new foundations and the neighbour’s existing foundations is central to whether the excavation provisions apply. Older properties often have shallow foundations, so the drawings and any trial holes are useful.
A new wall can be built wholly on your own land up to the Line of Junction, and a Section 1 Notice may be required. Building a wall astride the boundary requires the adjoining owner’s consent.
Where a wall is built at the Line of Junction, the Act can allow projecting footings below the neighbour’s land in some circumstances, subject to Notice and the Act’s requirements. Reinforced concrete foundations need the adjoining owner’s express consent.
Where the adjoining owner consents in writing, a dispute does not arise for that Notice and the notified work can proceed subject to the wider requirements of the project. A Schedule of Condition can still be arranged where appropriate.
A dispute arises for the purposes of the Act. The owners appoint an Agreed Surveyor or separate surveyors, who agree and serve a Party Wall Award dealing with the notifiable works.
Related
How the correct Notices are prepared, served and responded to online.
Learn moreWhat an Award covers, the surveyor appointment routes and the fixed fees.
Learn moreA dated record of the neighbouring property before works begin, where appropriate.
Learn moreWhere your neighbour dissents and separate surveyors are appointed.
Learn moreAn initial indication of whether a Party Wall Notice is likely to be required.
Learn moreDeep excavation, underpinning and engineering information.
Learn moreChimney breasts, steel beams and party structures.
Learn moreSend us your drawings and we’ll confirm whether the Act is likely to apply and agree a fixed fee before any work begins.
Practical guidance from our Party Wall Surveyors to help you understand the process and your options.
Planning Building Work
Planning an extension? Understand when excavation, boundary walls and work to shared structures may require a Party Wall Notice.
Read guide: Do I Need a Party Wall Notice for My Extension?
Planning Building Work
Understand the Party Wall rules for new walls at the boundary, including when neighbour consent is needed.
Read guide: Building at the Boundary: What Are the Party Wall Rules?The Party Wall Act
Special foundations beneath neighbouring land require previous written consent. Understand the statutory definition, possible alternatives and Bailey Rail case.
Read guide: Special Foundations and Consent: Section 7(4) and the Bailey Rail Case