House Extension and Electrical Work

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01/10/25, 16:19

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Site survey, drawings & planning (architect measurements, concept plans, planning/Building Reg applications).
Groundworks & structure: foundations, drainage alterations, block/brick walls, structural steel installation, roof frame and covering.
First‑fix services: new ring main, lighting circuits, consumer‑unit upgrade, plumbing pipe runs.
Insulation & weather‑tight shell — membranes, cavity batts, windows/doors fitted.
Second‑fix carpentry & electrics: sockets, switches, LED downlights, cabling test & NICEIC certificate.
Plaster, screed & finishes, plus make‑good to the existing house junction.
Site clearance & handover with building‑control sign‑off and electrical installation certificate.

Charge type	Low £	High £	Notes
Call‑out / minimum	350	1,100	Architect site survey £350; single‑storey design package £900–£1,100 Extension Architecture
Labour per hour	40	60	General builder c. £40‑£50/h Checkatrade; electrician £45‑£60/h Checkatrade
Materials	2,640	3,960	Per m² finished floor area; single‑storey extension £2,200–£3,300 ex VAT ≈ £2,640–£3,960 inc VAT Homebuilding
Disposal	190	450	Builder‑size (6‑8 yd) skip hire per week Checkatrade
Extras (scaffolding)	650	1,100	Two‑storey semi‑detached scaffold hire per week Checkatrade
TOTAL (most jobs come in here)	65,000	120,000	20‑30 m² single‑storey extension incl. full rewire & finishes Homebuilding

Typical: 10 – 16 weeks from break‑ground to completion for a single‑storey build with rewiring.
Longer: complex ground conditions, planning delays, bespoke glazing or steels, poor weather, or client variations.
Shorter: modular wall panels, straightforward trench foundations, or excellent access for materials.

What planning, Party‑Wall or building‑control approvals are included in your quote?
How will you phase electrical first‑fix and testing to keep the existing house live?
What contingency for hidden services or structural changes is allowed before extras apply?
Which warranty and certificates (NICEIC, Part P, structural steel calcs) will you hand over?
How do you manage programme and trades overlap to avoid idle weeks on site?
Will you provide a fixed price or cost‑plus contract, and what’s the
retention?
Who arranges & pays for scaffolding, skips and parking suspensions?

Access & parking: book bay suspensions for skips, concrete pumps and scaffold lorry.
Utility maps: locate gas, water and mains cables before trenching.
Neighbour liaison & Party‑Wall notices to head off objections.
Lead‑time items: order steels, glazing and consumer unit early to match programme.
Variation log: agree a written process for any spec changes.
Building‑control stage checks—foundation, damp‑course, insulation and final—notify 48 h in advance.