A bathroom renovation is the second most popular home improvement in the UK after kitchens. It's also where I see the most disastrous DIY attempts. Bathrooms involve water, electricity, and waterproofing — get any of these wrong and you're dealing with damp, mould, leaks into the room below, and potentially dangerous electrics in a wet environment.
What Does It Actually Cost?
Budget bathroom (keep layout, replace suite): £2,500–£5,000. Mid-range (new layout, full tiling, quality suite): £5,000–£10,000. Premium (underfloor heating, walk-in shower, designer fittings): £10,000–£20,000. London prices add 35-50% on top. Our Cost Index has detailed breakdowns by region.
The One Thing That Must Not Go Wrong
Waterproofing. This is the single most important step in any bathroom renovation and the one most commonly skipped by cheap fitters. Before any tiles go on the walls around the shower or bath, the substrate must be tanked with a waterproof membrane. This is a liquid or sheet membrane that creates a waterproof barrier between the tiles and the wall behind them.
Without tanking, water seeps through grout joints (grout is NOT waterproof), saturates the plasterboard behind, and causes damp, mould, and structural damage. I've seen bathrooms where the ceiling below collapsed because the shower was tiled directly onto untreated plasterboard. The renovation cost £6,000. The repair cost £8,000. Tanking costs £200-£400. Do the maths.
The Correct Order
1. Strip out — remove old suite, tiles, flooring. Check for damp and rot underneath.
2. First fix plumbing — move or install water supply and waste pipes to new positions.
3. First fix electrics — run cables for lighting, extractor fan, heated towel rail. Must comply with Part P bathroom zones.
4. Waterproof/tank — membrane on all wet areas. Allow 24-48 hours to cure.
5. Plasterboard and plaster — moisture-resistant board in wet areas.
6. Tile — walls first, then floor. Use flexible adhesive and waterproof grout in wet zones.
7. Second fix plumbing — install bath, toilet, basin, shower, taps.
8. Second fix electrics — fit lights, extractor, towel rail, shaver socket.
9. Paint and finish — moisture-resistant paint on untiled walls. Silicone sealant around bath and shower.
Ventilation Matters More Than You Think
Bathrooms without adequate ventilation breed mould. If your bathroom doesn't have an opening window, an extractor fan is mandatory under Building Regulations. Even with a window, a good extractor fan prevents condensation damage. Budget £100-£300 for a quality fan with a humidity sensor that activates automatically.
Choose Everything Before Work Starts
Every tile, every tap, every fitting. Have it all delivered and on site before the first tradesperson arrives. Nothing wastes more money than a plumber sitting idle for two days waiting for a shower valve to arrive because you hadn't ordered it yet. You're paying for their time regardless.
Plan Your Bathroom Renovation
Get the exact trades, costs, timeline, and materials. Phase-by-phase breakdown.
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