Planning your build: the key phases from A to Z
Building a house means completing dozens of steps in a precise order. Swapping two phases or missing an intermediate check can cost weeks of delay and thousands of pounds. Whether you are self building fully or partially, you need to understand the build timeline. Here are the key phases, from site preparation to finishing, with indicative durations and the control points you cannot afford to miss.
Overview: the 8 phases of a build
Before going into detail, here is the macro view:
| Phase | Indicative duration | % of budget |
|---|---|---|
| 1. Site preparation | 1–2 weeks | 3–5 % |
| 2. Foundations | 2–4 weeks | 8–12 % |
| 3. Structural works (walls, floors) | 4–8 weeks | 20–25 % |
| 4. Roof structure and covering (watertight) | 2–4 weeks | 10–15 % |
| 5. External joinery (weathertight) | 1–2 weeks | 8–10 % |
| 6. Second fix (insulation, plasterboard, services) | 6–12 weeks | 25–30 % |
| 7. Finishing (tiling, decorating, internal joinery) | 4–8 weeks | 10–15 % |
| 8. External landscaping | 2–4 weeks | 5–10 % |
| Total | 22–44 weeks | 100 % |
Tip — When self building, multiply all durations by 1.5 to 2. A part-time self builder working weekends and holidays will take 2 to 3 years where a professional team would take 10–12 months. Be realistic in your programme — an optimistic schedule is the surest way to demoralise yourself.
Phase 1: Site preparation
What happens
- Setting out: a surveyor stakes the corners of the house on the ground.
- Groundworks / excavation: strip topsoil (20–30 cm), level the platform, and create the working area.
- Utilities / groundworks (VRD): trench runs for service connections (water, electricity, drainage, telecoms).
Control points
- Setting out verified (dimensions, squareness, levels)
- Formation level clean and at the correct depth
- Service trenches excavated before foundations begin
Warning — Never start foundations without a surveyor setting out the building. A 10 cm error at this stage carries through to everything else — and it is irreversible once the concrete is poured.
Phase 2: Foundations
What happens
- Excavations: trenches for strip footings (or piles, raft, depending on the ground investigation).
- Reinforcement: steel fixed to the reinforcement schedule.
- Concrete pour: C25/30 concrete, vibrated, in frost-free conditions.
- Substructure: substructure walls (suspended floor or basement).
- Ground floor slab: concrete slab on hardcore or suspended floor construction.
Control points
- Ground investigation followed (foundation type as specified)
- Reinforcement inspected before pour (take photos!)
- Concrete properly vibrated and to the correct mix
- Curing time respected (28 days for nominal strength)
Tip — Take photos at every stage of the foundations (excavations, reinforcement, just before the pour). This is your evidence in any dispute or inspection, and is essential for your structural warranty (equivalent to a 10-year latent defects policy).
Phase 3: Structural works / superstructure
What happens
- Load-bearing walls: built in blockwork or timber frame.
- Ring beams and columns: horizontal and vertical, cast into the blockwork.
- Lintels: over all openings (windows, doors).
- Intermediate floor: for two-storey houses (concrete beam-and-block or cast slab).
Control points
- Wall plumb checked with plumb bob and laser level
- Ring beams cast at each wall-plate level
- Openings to correct dimensions (cross-check against window/door order sizes)
Phase 4: Roof structure and covering (watertight)
What happens
- Roof structure: erect the roof (cut roof or trussed rafters).
- Sarking / underlay: fix roofing underlay or breather membrane.
- Roof covering: lay tiles, slates or standing-seam metal.
- Flashings: gutters, valleys, ridge.
The “watertight” milestone
Watertight means the house is protected from rain: roof fully laid and sealed. This is a key contractual milestone — it often triggers a stage payment (40–45 % of the total finance).
Best practice — The watertight stage is the ideal moment for a formal site inspection, checking levels, plumb and roof integrity. Everything that will be hidden by the roof covering must be verified before it is closed in.
Phase 5: External joinery (weathertight)
What happens
- Windows and glazed doors: fitted in reveal, in the wall thickness or in a rebate.
- Front door: fitted with threshold and weatherproofing.
- Shutters: roller or casement.
The “weathertight” milestone
Weathertight means the house is closed up: windows and doors fitted. The interior is protected from the elements. Stage payment: 60–65 %.
From this point you can work inside in any weather.
Phase 6: Second fix
This is the longest phase and the one where the self builder is most heavily involved.
Order of works for second fix
The order is critical — some works must absolutely precede others:
| Order | Works | Why this order |
|---|---|---|
| 1 | First fix electrics (conduit, back boxes) | Conduit goes inside walls before insulation |
| 2 | First fix plumbing (pipes, waste runs) | Same — pipes before partitions are closed |
| 3 | Insulation (walls, roof, floor) | After services, before plasterboard |
| 4 | Plasterboard / partitions | Closes walls after insulation and services |
| 5 | Screed (sand-cement or liquid) | After plasterboard, before floor tiling |
| 6 | Wet room tanking | Before tiling in bathrooms and kitchen |
| 7 | Tiling | On dry screed (28 days min for sand-cement) |
| 8 | Second fix electrics (sockets, switches) | After decorating, or before — your choice |
| 9 | Second fix plumbing (taps, sanitaryware) | After tiling |
| 10 | Decoration | After plasterboard, before or after tiling |
Warning — The most common self-build mistake: fixing plasterboard before first fix electrics and plumbing are complete. The result: you have to cut back into partitions to run the services → wasted time and materials.
Second fix control points
- Part P certificate (electrical compliance) — required before connection to the DNO network
- Air pressure test (required under Building Regs Part L) — after insulation and external joinery are complete
- Building Control sign-off for drainage if private drainage — before backfilling
Phase 7: Finishing
What happens
- Decoration: walls and ceilings, minimum two coats.
- Floor finishes: tiles, timber, LVT depending on the room.
- Internal joinery: doors, skirtings, fitted wardrobes.
- Kitchen and bathroom fitting: units, worktops, taps.
- Second fix electrics: faceplates, light fittings.
Duration
Finishing almost always takes longer than expected — it is detailed work. Allow 4 to 8 weeks when self building, even for the “small” remaining jobs.
Phase 8: External landscaping
What happens
- Terrace / patio: concrete, timber decking or paving on adjustable pedestals.
- Access drive: gravel, concrete or tarmac.
- Fencing and gates: installed after the main build to avoid plant damage.
- Lawn and planting.
- Final DNO connection after electrical compliance certificate issued.
Tip — Externals are frequently pushed back due to budget pressure. Budget as a minimum for the access drive and patio from the outset in your initial budget — living without a hard standing or any outdoor space for two years is genuinely exhausting.
Typical programme: 120 m² house, partial self build
Total duration: 12 to 14 months for a partial self build (roof by a contractor, second fix done by yourself full-time). Double this if you can only work at weekends.
Planning pitfalls
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Underestimating curing and drying times — Concrete takes 28 days to reach nominal strength. Sand-cement screed needs 3 weeks before tiling. Plasterboard joints need 48 hours to dry before decorating. These times cannot be compressed.
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Forgetting lead times — Bespoke windows and doors take 4 to 8 weeks to manufacture. Ready-mix concrete needs 48 hours’ notice. Plan ahead.
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Ignoring the weather — Do not pour concrete below 5°C or above 35°C. Do not apply external decoration in rain. Build contingency into your programme.
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Moving on without checking — Each phase must be signed off before starting the next. A wall out of plumb is the moment to fix it — not after the plasterboard is on.
Key takeaways
A well-planned build is one that moves forward without having to go back. The phase sequence is non-negotiable — it follows the logic of construction. Master this timeline, build in realistic contingency, and inspect every phase before you move on. That is the foundation of a stress-free build.
Checklist: build planning
- Detailed programme written out covering all phases
- Realistic duration estimated (× 1.5 to 2 for self build)
- Second fix order of works understood
- Supplier lead times anticipated (joinery, concrete, materials)
- Intermediate inspections scheduled (Part P, air test, drainage sign-off)
- Weather contingency built in (2 to 4 weeks buffer)
- Budget aligned to phases (stage payment triggers)
- Photos planned at every stage (evidence and progress record)