Planning a basement is exciting—big gains in space and value without the SDLT pain of moving. It’s also the highest-risk category of domestic work under the Party Wall etc. Act 1996, so the party wall process must be watertight. Here’s a practical, no-nonsense guide to stay lawful, protect neighbours, and keep your programme realistic.
1) Accept the risk profile (and plan for it)
- Notice Dissents are the norm. Basements almost always trigger Section 6 (adjacent excavation) notices and are routinely dissented by adjoining owners. Expect the two-surveyor route (one for each owner), with a third surveyor selected as the safety-valve tribunal.
- Higher professional input = higher fees. Basement Awards demand more drawings, calculations, risk reviews and iterations than lofts or simple extensions. Build time and budget for this.
- Security for Expenses (s.12). For high-risk schemes (deep digs, underpinning, contiguous piles), adjoining owners often request security (a ring-fenced sum) to cover making safe or making good if works stall or cause loss.
2) Expect advising-engineer involvement
Competent adjoining-owner surveyors will instruct an advising/checking engineer to review:
- Temporary works (needles, propping, sequencing, back-propping)
- Final foundation system (underpinning, raft, piles, capping beams)
- Excavation/dewatering strategy (lowered water tables, heave control)
- Movement/settlement predictions and trigger levels
- Party wall interfaces (bearing into/against shared structures)
This extra engineering step adds time and fees, but it dramatically reduces risk and later disputes.
3) Understand “special foundations”
If a foundation includes “an assemblage of rods or beams” (i.e., reinforcement/steel integrated with the concrete), it is treated as a special foundation. Key practical takeaways:
- Consent issue at the boundary. Where your design places special foundations on or under the line of junction/onto the neighbour’s land, the adjoining owner can refuse that detail.
- Design fallback. If refused, be ready to revert to mass concrete or a detail that keeps reinforcement wholly on your land.
- Underpinning clarity. Many basement schemes use pin underpinning. Your engineer should set out whether reinforcement crosses the boundary; if so, prepare a plan B that preserves stability without requiring neighbour consent.
4) Programme: it’s a marathon, not a sprint
Basement Party Wall procedures involve more moving parts and deeper scrutiny than almost any other domestic project:
- Drawings pack must be complete: plans/sections/elevations, underpinning sequence, temporary works GA, dewatering notes, concrete specs, reinforcement intents and site logistics.
- Iterative engineer-to-engineer queries: expect a few rounds before everyone is comfortable.
- Monitoring set-up before dig: tell-tales, crack gauges or vibration/settlement monitoring often required, with green/amber/red trigger levels and a Method Statement for what happens at each threshold.
- Access protocols (s.8): scaffold, plant routes, hoarding, protection to paving/planting, daily housekeeping, and reinstatement are typically baked into the Award.
5) What a robust Basement Party Wall Award usually includes
- Time & manner of works: working hours, sequencing, breaks in works during key neighbour events if agreed
- Temporary works: specific propping schemes and hold points for inspections
- Excavation & dewatering: method, staging, maximum open duration of trenches/pins, contingency for inflows
- Monitoring: locations, frequency, thresholds, reporting, and stop-work/escalation steps
- Construction controls: hand tools adjacent to party elements, non-percussive breaking, dust/soot containment (covering flues/vents), noise/vibration limits
- Access licence under the Act: defined routes, protection, hours, security, and making-good duties
- Damage & making good: liability, valuation route (quotes vs. schedule rates), payment terms, and further award mechanism if needed
- Variation protocol: how material design changes are notified and approved before implementation
6) Managing damage and claims—stay calm, stay procedural
- Report early; record well. Notify surveyors immediately; log with dated photos/video.
- Causation first. Surveyors (with engineer input if needed) confirm whether damage is attributable to the notifiable works.
- Make good or cash settlement. You can propose your contractor to make good, or fund the neighbour’s contractor against reasonable quotes.
- If no agreement: the surveyors determine liability and quantum via a further/variation Award—which is enforceable.
7) Basement pre-start checklist
- Final structural set frozen (permits, Building Control route aligned)
- Section 6 notice(s) validly served ≥1 month before excavation (earlier is wiser)
- Section 1 notice if working on/astride the boundary (note: astride needs consent)
- Award served with full engineering pack attached
- Monitoring installed and baseline readings taken before works
- Contractor briefed on Award; method statements match Award obligations
- Security for Expenses resolved (if requested/awarded)
- Access plan agreed and neighbours informed of key dates
Typical pitfalls (and easy wins)
- Incomplete drawings in the notice → Invalid for Section 6; include clear location & depth info.
- Design drift on site → Notify surveyors before changing temporary works, sequences, or depths.
- Skipping monitoring → If required by the Award, it’s not optional.
- Underestimating water → Dewatering affects neighbours; plan containment and monitoring.
- Communication silence → Weekly updates to neighbours reduce friction and claims.
Simple Survey — clear, fixed pricing (nationwide)
Straightforward fees
- Party Wall Notice service: £25 per adjoining ownership (multi-notice bundles discounted)
- Act administration as Agreed Surveyor (single surveyor): typically £300 fixed-fee (depends on complexity and number of notices/owners)
- Two-surveyor route (we act for the Building Owner): fixed-fee proposals from £325 for our side
We work to keep your neighbour’s surveyor’s hourly fees reasonable and contained.
Why Simple Survey
- RICS-qualified building surveyors (deep building-pathology and basement experience)
- Nationwide, fixed-fee model—no surprises
- Calm, neighbour-first administration that keeps complex basements moving
Planning a basement?
Email your drawings for a free notifiability review and a fixed-fee plan. We’ll serve valid notices, coordinate the engineering dialogue, agree a robust Award, and brief your contractor—so your basement stays safe, lawful, and on programme.
Our fees are always fixed. We’re nationwide. We’re both experienced and qualified.