How do I know if I need piles?

Soil investigation (boreholes + tree survey) at design stage. NHBC tree guide and BRE/Eurocode rules dictate pile requirement based on tree species, distance and soil shrinkability.

Sometimes — removing the offending tree (with proper TPO/CA checks) or deepening strip foundations. Often piling is cheaper than 3m+ strips.

How disruptive is piling?

Mini-piling rig: 2–4 days on site, modest vibration, noticeable noise. Neighbours notified via party wall agreement; works typically 8am–5pm.

Does Builderr handle piling?

Yes through specialist piling subcontractors with our engineer's design. Programmed alongside groundworks.

Quick Answer

How much does piling cost for a London extension?

Piled foundations for a London extension typically cost £12,000–£35,000 depending on pile count, depth and rig access. Mini-piling (most common in London — tight-access rigs): £180–£280 per linear metre. Typical extension needs 6–14 piles at 6–12m depth — total £12k–£28k. CFA piling (continuous flight auger) for larger footprints: £200–£320/m. Adding piling adds 2–4 weeks to the programme.

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When you need piles

Three triggers: trees within influencing distance (London Clay shrinkable soil + tree roots — NHBC tree guide), made ground or weak strata revealed by soil investigation, or where strip foundations would be uneconomic at depth >3m. London Clay sites in Wandsworth, Lambeth and Richmond often need piles where mature trees are present.

Pile types

Mini-piles 150–300mm diameter, 6–15m deep — fit through standard garden side access. Driven steel-cased: best for variable ground. CFA: large rigs, only viable on open-access sites. Screw piles: niche, used for lightweight extensions and timber-frame rears. Engineer selects based on soil investigation.

Hidden costs

Soil investigation £1,500–£3,500 (boreholes + lab tests). Engineer's piled foundation design £1,200–£2,800. Rig access prep (drive plates, gravel mat): £400–£900. Excavation of pile caps and ground beams: £1,800–£4,200. Total piling package typically 15–25% of structural budget.

Ready to get started?

Senior consultant call within one business hour. Free desk-based planning assessment. Fixed-scope quote — no provisional sums, no day-rate creep.