What structural planning does an extension need? In order: existing-structure and ground homework (trees, drains, previous alterations), engineered design (openings, new structure, foundations) from your architect's drawings, Building Regulations submission, party wall notices served months before excavation, and construction-stage discipline — build to the calculations and get every discovery re-engineered rather than improvised.
Extension Structural Planning Checklist
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Before design
Design stage
Approvals & notices
Construction
Important: this tool provides general, indicative guidance only. It is not a survey, a diagnosis or a quotation, and it cannot assess your specific property. Figures are broad London planning ranges; the appointed professional confirms actual fees and any repair costs are confirmed by contractors pricing an engineered specification. If you are concerned about your property, request a structural assessment or call.