Why sequence matters more than any single trade
Every stage of a renovation covers the one before it. First-fix cabling disappears behind plasterboard, plasterboard disappears behind skim, skim disappears behind paint. Install anything out of order and it has to come back out — which is why a project run in the wrong sequence costs more than the same project run slowly in the right one. The sequence below is the one nearly every domestic project in London follows: strip-out, structure, weathertight envelope, first fix, plaster, second fix, decoration, sign-off. Where a programme slips, it almost never slips because a trade worked slowly; it slips because a trade was booked before the one in front of it had finished.
Before site: drawings, structure, party wall
Three appointments sit ahead of the building work. The designer or architectural technologist produces the measured survey and the drawing set that every later trade prices and builds from. The structural engineer sizes any steel and designs new foundations, and issues the calculations building control checks — on a London terrace that is nearly every project, because the rear wall almost always comes out. The party wall surveyor is needed where work affects a shared wall or excavates within 3 metres of a neighbouring structure, or 6 metres for deeper foundations. The Party Wall etc. Act 1996 sets notice periods of 2 months for work to a party structure and 1 month for line-of-junction and excavation notices, and those run in calendar months regardless of how ready your builder is. Party wall is the single item most likely to move a start date when it is left until last.
Stage 1 to 3: strip-out, structure, weathertight
Strip-out is where the survey meets reality. Floors come up, plaster comes off, and the things a survey could not see — a chimney breast removed without support, a joist notched to nothing, a drain running where no drawing shows it — appear in the first week rather than the last. Budget a contingency specifically for this stage. Structure follows: foundations, steelwork, load-bearing alterations, and the new roof. Then the envelope is closed — roof covering, windows, external doors — so that every internal trade after this point is working in a dry building. Attempting first fix before the building is weathertight is the most common cause of ruined plasterboard and of a second visit from the same trade.
Stage 4: first fix
First fix is everything that later disappears inside a wall or a floor: electrical cabling, pipe runs, waste and soil connections, extract ductwork, studwork, and floor structure. It is the stage where the drawings earn their fee, because once boards go on, the position of every socket, radiator and waste is fixed at the cost of opening the wall again. Fixed electrical work in a dwelling is notifiable under Part P of the Building Regulations, so the electrician should be registered with a competent-person scheme such as NICEIC or NAPIT — otherwise the work needs separate inspection by building control before it can be certified. Anyone working on gas appliances or pipework must be on the Gas Safe Register, which replaced CORGI as the statutory scheme on 1 April 2009.
Stage 5: plastering, and why it is the pinch point
Plastering sits between first fix and decoration, and the flatness of the wall it produces sets the quality of every coat of paint that follows. It is genuinely skilled work, and it cannot be corrected downstream — a decorator can fill and sand, but poor plastering shows under raking light for the life of the wall. It is also the stage most often compressed, because it sits at the point in the programme where all earlier slippage has accumulated. Book it early. Good plasterers are booked weeks ahead, and a firm such as London Plastering Service, which covers skimming, rendering and dry lining across London, is the kind of specialist worth securing while the structure is still going in rather than phoning once the boards are up. A 2-week wait for a plasterer stops every trade behind it.
Stage 6: second fix and the wet rooms
Second fix connects to what first fix left: sockets and switches, radiators and towel rails, sanitaryware and brassware, kitchen units, internal doors, skirting and architrave. Bathrooms and kitchens are where a specialist reliably outperforms a generalist, because a bathroom compresses drainage falls, electrical zones, waterproofing and tiling setting-out into roughly four square metres — and the elements that fail are the ones nobody can see once the room is finished. A specialist renovation firm such as London Renovate handles design, supply and installation of bathrooms and interior finishes as a single package, which removes the familiar argument about whether a defect belongs to the fitter or the supplier. Whoever does it, brief them from the drawing rather than a mood board: the layout has to work with the soil stack before it can look like the picture.
Stage 7 and 8: decoration, snagging, sign-off
Decoration and flooring are the last trades in, and the ones every occupant judges the whole project by. Good decorators do the making-good — filling, caulking, sanding — that turns fresh plaster into a flat finish, and that work takes the time it takes. Then comes sign-off: the building control completion certificate, the electrical installation certificate, the gas safety certificate where applicable, and a written snag list agreed before the final payment is released. Hold a meaningful retention until snagging is complete. A snag list agreed in writing while the scaffold is still up gets fixed; the same list raised after final payment becomes a favour.
Where London programmes actually slip
Four things, in our experience, account for most of the lost weeks on a London job. Party wall notices served late, because the statutory clock runs in calendar months and cannot be compressed. Structural steel fabricated to a drawing that changed after it was ordered. Materials with long lead times — sanitaryware, bespoke glazing and staircases in particular — ordered after the strip-out rather than before it. And the finishing trades booked to a date fixed before the structure started, then squeezed when the structure overran. None of those are trade failures. They are all sequencing decisions made months earlier, which is precisely why the drawings and the programme deserve more attention than the choice of any individual contractor.
