National Extensions Dispatch handles single-storey rear extensions, side returns, and wraparounds from planning through build control sign-off. We manage Planning Permission applications, Building Regs approval, Party Wall notices, beam calculations, and CIL payments—then build to completion.
Planning submitted week 1. Build Regs approved week 3. Foundations week 4. Roof on week 7. Signed off week 10.
RIBA-qualified architectural designers handle drawings (1:50 scale plans/elevations required for Planning). Structural engineers provide SE calculations for steel beams (Building Regs Part A compliance). CIAT-qualified project managers coordinate trades. We work to Building Regulations 2010 (as amended 2022) and handle Local Authority liaison.
From planning application to building control sign-off
3m-6m rear projections (4m max for detached, 3m for terraced/semi under Permitted Development). Typical 4x4m kitchen extension: £35k-45k build cost + £2k Planning fees if needed + £1,200 Building Regs. Timeline: 2 weeks Planning decision (or PD cert), 3 weeks Build Regs approval, 6-8 weeks build. Includes strip foundations (1m deep), cavity walls (100mm insulation, U-value 0.28), structural glazing/bifolds, screed floors. Party Wall notices served 2 months before (£700-1k surveyor fees). We provide 1:50 scale drawings, structural calcs, SAP calculations for Part L thermal compliance.
Infill narrow side passages (common on Victorian/Edwardian terraces). Side return: 1.2m-2m width gain. Wraparound (side + rear): creates large open-plan kitchen/diner. Cost: £40k-60k depending on size. Always needs Planning Permission (not Permitted Development). Structural challenge: removing side/rear walls requires steel beam calculations (203x203 UC sections typical). Building Regs critical: Part B fire regs (30min fire doors to hallway), Part F ventilation (mechanical extract). Timeline: 8-10 weeks Planning, 3 weeks Build Regs, 8-10 weeks build. Party Wall Act applies both sides—expect neighbour liaison.
Adding bedroom/bathroom above kitchen extension. Cost: £60k-90k (roughly 1.5x single-storey cost due to first-floor structure, stairs, additional plumbing). Requires full Planning Permission—cannot use Permitted Development if over 3m high at boundary. Structural complexity: load-bearing calculations for first floor (timber joists or steel beams), foundation depths increase (1.2m-1.5m). Building Regs intensive: Part B fire escape (bedroom windows must allow escape), Part E sound insulation (floor separating rooms), Part L thermal (wall/roof insulation). Timeline: 10-12 weeks Planning, 4 weeks Build Regs, 12-16 weeks build. Party Wall Act applies if within 3m of boundary.
Handling Local Planning Authority (LPA) submissions when Permitted Development doesn't apply. We prepare: 1:50 scale plans/elevations/sections, site location plan (1:1250 scale), Design & Access Statement, CIL forms. Standard householder application: £206 fee, 8 weeks decision time. Permitted Development Certificate (checking if you need Planning): £120 fee, 8 weeks. We liaise with planning officers, respond to neighbour objections, amend drawings if needed. Success rate: 92% first-time approvals. If refused, we handle appeals (6 months written process) or revise design. Typical planning cost: £800-1,200 for drawings + LPA fees.
Full Plans application to Building Control (council or private inspectors). Required before building starts (£1,200-1,500 fee for typical extension). We submit: structural calculations (SE-stamped), SAP calculations (Part L thermal performance), ventilation strategy (Part F), drainage plans (Part H). Approval takes 2-5 weeks. Inspections during build: foundations, DPC, drainage, structural frame, insulation, completion. Building Control issues Completion Certificate when satisfied—essential for selling property. Without this, solicitors flag extension as unauthorised (mortgage/sale issues). We coordinate all inspections and ensure compliance—no surprises.
Legal requirement when building within 3m of neighbour's property or working on shared wall. Process: serve Party Wall notices 2 months before work (1 month for non-excavation). Neighbour consents or dissents. If dissent, appoint surveyors (yours, theirs, or shared "agreed surveyor"). Surveyor prepares Party Wall Award (document setting work scope, access, dispute resolution). Surveyor fees: £700-1,500. Covers you legally—neighbour cannot stop work if Award in place, and provides damage dispute mechanism. Ignoring Party Wall Act: neighbour can injunction to stop work, claim damages, delay project 6-12 months. We handle notice service and surveyor liaison.
From concept drawings to Building Control sign-off
Tell us your timeline and what you want to build