When you appoint a main contractor, the sequencing and coordination of trades is their problem. When you manage a project directly, appointing each trade separately, it becomes your problem. The advantage is cost: removing the main contractor's margin (typically 15-25% of trade costs) can be substantial on a larger project. The disadvantage is that you're taking on a job that requires real skill, knowledge, and sustained attention.
This guide assumes you've made that decision and focuses on how to do it well.
Building a Programme
The foundation of multi-trade management is a written programme that sequences every trade and shows their dependencies. Trade B cannot start until Trade A has finished. If Trade A is late, Trade B is delayed, and the knock-on effects cascade through the rest of the project.
A basic programme for a ground floor extension might look like this:
- Groundworks (excavation, foundations, drainage): 2-3 weeks
- Bricklayer/blockwork (walls to plate level): 2 weeks
- Carpenter/joiner (roof structure, joist hangers): 1 week
- Roofer (roof covering, flashings): 1 week
- Window and door installation: 1-2 days
- First-fix plumber (heating, underfloor pipes if applicable): 1 week
- First-fix electrician (cable runs, back boxes): 1 week
- Plasterer: 1-2 weeks
- Second-fix electrician (sockets, switches, consumer unit): 2-3 days
- Second-fix plumber (radiators, taps, sanitary ware): 2-3 days
- Kitchen or joinery fitter: 2-3 days
- Tiler: 1 week
- Decorator: 1-2 weeks
- Floor finishes: 1-2 days
That's a simplified illustration. Real projects have more complexity, overlap between trades on different areas of the building, and dependencies on building control inspections. Use a spreadsheet or a simple Gantt chart. The tool doesn't matter; the discipline of thinking through the sequence matters enormously.
Booking Trades in Advance
Good tradespeople are booked weeks or months in advance. If you approach a tiler three days before you need them, expecting them to be available, you'll either wait or use whoever is available at short notice (which is rarely the best option).
Book every trade before the project starts, not as you need them. Once you have a programme, you know approximately when each trade is needed. Give each contractor the programme dates, build in some contingency, and confirm bookings in writing.
Discuss with each contractor what notice they need to mobilise and what happens if the previous trade runs late. Most experienced tradespeople are used to this: they have other work and can usually flex their start by a few days if you give enough warning. What they can't tolerate is a call on Monday asking if they can start Tuesday.
Understanding First and Second Fix
Many trades have two phases: first fix and second fix. Understanding this is essential for sequencing correctly.
Electrical first fix: Running cable to all points (sockets, switches, lights, consumer unit) before plastering. Cable is chased into walls or run through floor voids and ceiling joists. Outlet boxes are fitted. No visible equipment yet.
Electrical second fix: After plastering and decorating, fitting sockets, switches, light fittings, and consumer unit. Testing and certification.
Plumbing first fix: Pipe runs in walls and floors, valve positions, underfloor heating if applicable. Before plastering and screeding.
Plumbing second fix: Radiators, taps, sanitary ware, boiler connections. After plastering and tiling where relevant.
Plastering happens between first and second fix for both plumbers and electricians. This is a critical sequencing point. If the plasterer starts before first fix is complete, you have a problem. If second fix happens before decorating is complete, you risk damage to new fittings. Discuss the handover points explicitly with each trade.
Get all first-fix trades to verify each other's routes before boarding or plastering. Electricians sometimes run cables through spaces that conflict with plumbing pipes. Catching this before the walls are closed costs nothing. Cutting open finished plasterwork costs time, money, and goodwill.
Managing Clashes and Dependencies
Trade clashes happen when two trades need to work in the same space at the same time, or when one trade's work needs to be completed before another can proceed. Common clashes to plan for:
Plumber and electrician competing for space in the same ceiling void. Resolve this by having both present at the same time to agree the routing before either commits to a route.
Screed drying time. A liquid screed needs 24-48 hours per 10mm of depth to dry before flooring can be laid. A 75mm screed needs a week minimum. Trying to lay tiles or flooring on a damp screed causes adhesion failure. Build drying time into the programme explicitly.
Plaster drying time. Plaster needs at least four weeks to dry before decorating with solvent-based paints, and preferably two weeks before water-based primer. Rushing this causes paint failure. Build it in.
Building control inspections. Some work cannot proceed until a BCO has inspected and approved the previous stage. The programme must include notification and inspection windows at the relevant stages.
Communicating Across Trades
When you're managing multiple trades, you're the communication hub. Each trade needs to know what the trades before and after them are doing, where they're running services, and what they need from the previous trade to start. They won't get this information from each other automatically; you need to facilitate it.
Before each trade starts, brief them on what the previous trade has done, any issues to be aware of, and what they need to leave for the next trade. Ask them to flag any clashes or problems they see immediately, not on their last day.
Keep a site diary. Record when each trade is on site, what they completed, any issues, and what's outstanding at handover to the next trade. This is your record of what happened and when, and it's invaluable if any question arises about sequencing or blame for a problem.