Twelve Weeks in Didsbury: A Week-by-Week Account of a Rear Extension That Stayed on Budget
Domestic extensions rarely get the forensic treatment they deserve. Too often, the trade reads about glossy finished projects with no mention of the weather delays, the client who changed her mind about bi-fold doors, or the subcontractor who vanished for a fortnight. This project in Didsbury — a 32 square metre single-storey rear extension on a 1930s semi — is documented differently. Every figure quoted below was drawn from the actual job sheet, shared with the homeowner's consent.
The Brief and the Numbers
The clients, a couple with two young children, wanted an open-plan kitchen and family space replacing a dated galley kitchen and a lean-to utility room. Planning permission was not required thanks to permitted development rights, though a lawful development certificate was secured for £259 to reassure future buyers.
The contracted price came to £68,500, with a provisional sum of £2,400 for ground conditions. Programme: twelve weeks, with a two-week buffer agreed at the outset — a decision the builder later described as the single best move of the job.
Weeks 1–2: Groundworks and the First Lesson
Demolition of the lean-to and excavation of 900mm strip foundations took ten working days, two days longer than planned after the crew hit a buried concrete slab from an old outbuilding. The contingency covered the extra muck-away (£480) without drama.
Lesson one: never price a Didsbury excavation without assuming the unexpected. Victorian and interwar suburbs across Manchester hide decades of buried structures.
Weeks 3–5: Structure Takes Shape
Foundations were poured in week three, with block and beam flooring following — chosen over suspended timber for its acoustic performance and speed. By the end of week five, the steel RSJs were in place and the oaklite roof lantern opening was formed.
Building control inspections were booked through a private approved inspector rather than the local authority. The builder's reasoning: greater scheduling flexibility. Three inspections were completed on time — foundations, damp-proof course, and the structural steel check.
Weeks 6–9: Weathertight and On Site
The roof went on in week six, and the extension was weathertight by the end of week seven — crucial, given the timing. The following fortnight covered first fix electrics, plumbing runs for the new kitchen, plastering and screeding.
One subcontractor change happened here. The original plasterer took another job mid-programme; the builder's regular second choice was on site within three days. The lesson for small firms: maintain a bench of at least two trusted trades for every critical stage. Manchester's building boom means good plasterers, bricklayers and electricians are rarely short of work.
Weeks 10–12: Second Fix and Snagging
Kitchen installation, tiling, decoration and flooring filled weeks ten and eleven. The bi-fold door commissioning and the building control final certificate landed in week twelve. A snagging list of 23 items — mostly paint touch-ups and door alignment — was cleared within four working days.
Final cost: £69,900, roughly two per cent over contract, absorbed by the contingency. Handover took place 84 days after breaking ground.
What Small Builders Can Take From This
Three practices defined the job. First, a written weekly client update — a short email with photos — eliminated the anxiety that derails domestic projects. Second, the buffer week was protected; it was never treated as spare time. Third, every Building Regulations inspection was booked a week ahead, avoiding the cascading delays that idle labour.
Extensions of this scale are the bread and butter of Britain's small building firms. Delivering them predictably — on programme, near budget, with the client still on speaking terms at the end — is what separates a sustainable business from a hand-to-mouth one.
