A bathroom is the hardest room in the house to price and the easiest to lose money on. It stacks half a dozen trades into a few square metres, and most of the risk is hidden behind the old tiles. Here's a method that turns "gut feel" into a number you can defend — and a full worked example.
Price the parts, not the room
Never price a bathroom as one lump. Break it into the components that actually drive cost, then add them up:
- Strip-out & disposal — labour + skip. Older buildings hide surprises here.
- Waterproofing & screed — the part clients never see and never value, but the part that causes callbacks if you skimp.
- Tiling — split into labour (per m²) and material (per m², from real supplier prices).
- Sanitary suite — WC, basin, shower/bath, taps, priced per unit.
- Fit & connections — plumbing and installation labour.
- Buffer — a single contingency line that prices the unknowns once.
A worked example
A small guest bathroom, roughly 4 m² floor, 18 m² of tiling:
| Component | Basis | CHF |
|---|---|---|
| Strip-out & disposal | 1.5 days | 1,260 |
| Waterproofing & screed | 6 m² + consumables | 820 |
| Tiling — labour | 18 m² | 1,980 |
| Tiling — material | 18 m² @ supplier price | 1,980 |
| Sanitary suite | WC + basin + shower | 2,650 |
| Fit & plumbing | 2 days | 1,680 |
| Subtotal | 10,370 | |
| Contingency buffer (12%) | absorbs the unknowns | 1,244 |
| Fixed price (excl. VAT) | 11,614 |
Illustrative figures for a small bathroom in the Basel region — adapt to your own labour rate and supplier prices. The structure is what matters.
Where jobs actually lose money
- Under-costing the strip-out. In older Swiss housing stock, what's behind the tiles is the biggest variable. Walk the room, tap the walls, and price for what you might find — that's what the buffer is for.
- Forgetting the consumables. Adhesive, grout, silicone, waterproofing and screed add up. Cost them by coverage (m²), not by guess.
- Quoting a range. "Between 10k and 14k" reads as "14k, probably more." One fixed number reads as competence.
Keep it defensible
The reason to build a price up from parts isn't bureaucracy — it's that every line is referenceable. When a customer asks "why so much for the tiling?", you have an answer: labour per m² plus material at the current supplier price. This is also why Mastro cites the live supplier price and article number on each material line — a price you can point to beats a price you have to defend.
Price the parts, buffer the unknowns once, and give one fixed number. Do that and your quotes stop being a gamble and start being a competitive advantage.
Related: how pricing and buffers work · fixed-price vs hourly estimates.