Party Wall Matters for London Extensions
Understand your rights and obligations under the Party Wall Act when extending terraced and semi-detached properties in London.
Party Wall Facts
London extension reality
⚠️ Start party wall process 3+ months before construction
When Do Party Wall Procedures Apply?
Three main categories of work trigger Party Wall Act procedures. Most extensions fall into one or more categories.
Work Directly to the Party Wall
Any structural alterations affecting the shared wall
💡 Most single-storey rear extensions require this
Common Examples:
- Inserting steel beams into party wall
- Creating openings in party wall
- Underpinning foundations
- Raising party wall height
Excavation Near Boundaries
Digging foundations within 3m/6m of neighbour's building
💡 Complex calculations - always get professional advice
Common Examples:
- New foundations within 3m and deeper than neighbour's
- Any excavation within 6m and below 45° line
- Basement extensions and deep foundations
- Garden studios with foundations
Special Foundations and Boundary Work
Building on or astride the boundary line
💡 Rare in typical extensions but can apply
Common Examples:
- Foundations built on boundary line
- Retaining walls on boundaries
- New party walls between properties
- Boundary wall construction
Common Extension Scenarios
Likelihood of party wall procedures by extension type, with typical costs and timelines.
Single-Storey Rear Extension
Why: Steel beam typically inserted into party wall for support
Process: Section 2 notice for work to party wall
Two-Storey Rear Extension
Why: Multiple beams, possible wall raising, excavation
Process: Section 2 and possibly Section 6 notices
Loft Conversion
Why: Depends on structural work to party walls
Process: Section 2 if beams inserted into party wall
Basement Extension
Why: Deep excavation always triggers procedures
Process: Section 6 (excavation) + Section 2 (walls)
The Party Wall Process
Step-by-step timeline from initial notice to construction completion. Allow 3+ months before starting work.
Serve Notice
2 months before work starts
Formally notify neighbours of intended work
💰 Cost: £0 (if you do it yourself)
Requirements:
- Party Wall Notice served by registered post
- Detailed drawings and structural calculations
- Clear description of proposed work
- Statutory form correctly completed
Pro Tips:
💡 Use registered post for proof of service
Neighbour Response
14 days for neighbour to respond
Neighbour can consent or dissent to the work
💰 Cost: £0
Requirements:
- Written consent (rare) - work can proceed
- Written dissent - triggers formal process
- No response - deemed dissent after 14 days
- Counter-notice if they want protective work
Pro Tips:
💡 Most neighbours dissent to protect their interests
Appoint Surveyors
10 days after dissent
Select surveyors to manage the formal process
💰 Cost: £2,000-£4,000 for simple extensions
Requirements:
- Agreed surveyor (ideal but rare)
- Two surveyors (one each) plus Third Surveyor
- All must be qualified party wall surveyors
- Building owner pays all surveyor fees
Pro Tips:
💡 Try to agree on single surveyor to reduce costs
Party Wall Award
4-6 weeks
Surveyors produce formal agreement document
💰 Cost: Included in surveyor fees
Requirements:
- Schedule of Condition (pre-work survey)
- Method statements for protection
- Access arrangements agreed
- Dispute resolution procedures
Pro Tips:
💡 Award must be in place before work starts
Construction Phase
Duration of building work
Work proceeds under Party Wall Award terms
💰 Cost: Potential damage costs
Requirements:
- Comply with all Award conditions
- Provide required notices to surveyor
- Neighbour access for monitoring
- Rectify any damage caused
Pro Tips:
💡 Good contractors reduce party wall risks
Party Wall Cost Breakdown
Detailed breakdown of party wall costs. Remember: building owners pay all surveyor fees.
Building Owner's Surveyor
£1,500-£2,500Your surveyor to manage the process
One-off fee
Adjoining Owner's Surveyor
£1,500-£2,500Neighbour's surveyor (you pay)
One-off fee
Third Surveyor
£500-£1,000Dispute resolver (if needed)
Only if disputes arise
Schedule of Condition
£400-£800Pre-work survey of neighbour's property
One-off
Legal Fees
£300-£600Neighbour's legal advice (you pay)
If neighbour instructs solicitor
Potential Damage Costs
£500-£5,000+Repair any damage caused by work
If damage occurs
Total Party Wall Budget
Budget £2,000-£4,000 for simple extensions, £4,000-£8,000 for complex projects. Add 15% contingency for potential complications.
Building Owner Pays All Costs
Rights and Obligations
Understanding what you can and cannot do under the Party Wall Act helps set realistic expectations.
Building Owner Rights
Rights:
- Right to carry out necessary structural work
- Right of access to adjoining property (with notice)
- Right to temporary protection and support
- Right to recover costs if work benefits neighbour
Obligations:
- Serve proper notices at correct times
- Pay all party wall surveyor fees
- Compensate for damage caused
- Provide temporary accommodation if required
Adjoining Owner Rights
Rights:
- Right to consent or dissent to proposed work
- Right to appoint own surveyor (at building owner's cost)
- Right to receive Schedule of Condition
- Right to compensation for damage or inconvenience
Obligations:
- Allow reasonable access for surveys
- Respond to notices within statutory periods
- Not unreasonably delay the process
- Comply with Party Wall Award terms
Remember
Party wall procedures exist to protect both parties' interests. While they add cost and time, they provide legal protection and clear frameworks for resolving disputes.