What a SW London Extension Project Manager Does Week by Week

Homeowners often ask what a project manager “actually does all day.” The honest answer is: it changes with the week. On a South West London extension the work is less about standing in a hard hat looking busy, and more about keeping decisions, costs and trades one step ahead of the programme — on your side of the table, not the builder’s.

This is a typical pattern for a rear or side-return extension on a Victorian terrace. Your project will differ; the sequence rarely does.

Before anyone breaks ground

Week −4 to −2 (sometimes longer): quotations and scope. Three quotes for “the same extension” are rarely the same job. The work here is lining exclusions, provisional sums, steels, drainage, scaffolding and making-good into one comparable picture — then putting gaps back to the builders in writing. This is usually the highest-value block of time on the whole project. See how to compare builder quotes.

Week −2 to −1: pre-start. Party wall notices (if not already moving), building control route confirmed, lead-in items identified (glazing and kitchens especially), a simple decision schedule so finishes are not chosen the week a trade needs them, and a live budget with contingency held where it belongs — not buried inside an optimistic headline.

On streets in Earlsfield, Wandsworth or Fulham, this is also when shallow Victorian foundations, shared drains and conservation constraints get checked against what the quote actually priced — not what everyone hoped it priced.

Early site weeks

Strip-out / opening up: the house tells you what it has been hiding. Old repairs, unexpected structure, drains in the wrong place. The job is to cost surprises properly while the plan can still change, rather than absorbing them as vague “extras” later.

Groundworks: foundations and any underpinning. This is where SW London budgets are most often lost. Extra depth agreed casually on site without a price becomes an invoice. Someone client-side needs to be close enough to catch that in the week it happens.

Structure: steels, openings, roof to the extension. Once it is in, changing your mind is expensive — so this is the check that what is being built still matches the drawings and the quote you signed, and that steel lead times have not silently slipped the programme.

Mid-build

First fix: wiring, plumbing, heating — everything that disappears behind plasterboard. Socket positions, waste runs, provision for appliances not yet bought. Cheap to adjust now; expensive after skim.

Decision chase: kitchens, sanitaryware, flooring, ironmongery, external finishes. A large part of the week can be making sure choices arrive before the trade that needs them, and sourcing bigger items at trade price where that saving is real — see trade prices vs retail.

Variations and payments: every change logged and agreed before it is just “on the bill.” Payment requests sense-checked against progress, not optimism.

Late weeks and handover

Second fix and finishes: the last ten per cent takes the longest, and attention naturally drifts toward the builder’s next job. Written snagging lists, worked through methodically, are what closes an extension out rather than leaving a trail of “we’ll come back.”

Handover: certificates, manuals, outstanding items, and a clear line between complete and merely almost complete.

What this is not

It is not architectural design, structural calculations, or acting as the main contractor. Those sit with the right professionals — the boundaries are listed on services. It is also not a guarantee that every project needs full weekly attendance; some clients only want pre-construction scrutiny, others want someone on the ground throughout.

What it costs, roughly speaking

There is no honest single figure for every extension. UK market guides describe percentage, fixed, retainer and day-rate models; I quote against the project in front of me. Renovation project manager cost explains the models and the conflicts to watch for, without dressing market ranges up as “our price list.”

If you are planning an extension

If you want a plain read on whether your job needs this level of support — or you already have quotes and want them reviewed — get in touch. No charge for the initial conversation, and a straight answer if you would be better running it yourself.

Related: how long a kitchen extension actually takes and does a project manager’s fee pay for itself?.