How to plan a renovation budget that holds

The most common budgeting mistake is asking "how much does a bathroom cost?" before deciding what the bathroom will be. Write down, room by room, what will be removed, what will be repaired and what will be new: wall finishes, floor, electrics, plumbing, heating, doors, fixtures.

A clear scope does two things: it makes quotes comparable, and it shows the dependencies — new tiles may mean new pipes behind them, a new floor may mean new skirting and trimmed doors.

Budgeting in this order helps you spot gaps (who makes good the walls after the electrician?) and plan payments in stages instead of all at once.

1. Strip-out and disposal
2. Structural repairs, windows and external work
3. First fix: electrics, plumbing, heating pipes behind walls and floors
4. Plastering, screeds, drying time
5. Tiling, flooring, second fix of electrics and plumbing
6. Decorating, fitting kitchens and furniture

• Give every contractor the same written scope.
• Ask whether materials, disposal, protection of floors and cleaning are included.
• Check how taxes are shown — with or without VAT, depending on your country.
• Ask for unit prices (per m², per point, per metre) so you can recalculate when the scope changes.
• Agree in writing what happens with extra work: how it's priced and approved.

Old buildings hide things: rotten joists, old wiring, uneven floors, pipes in unexpected places. A reserve is not a sign of poor planning; it's part of it. A common rule is 10% for simple, well-defined work and 15–20% for older houses or when walls, floors and pipes will be opened up.

Keep the reserve separate and only use it for genuine surprises. Once the work is finished and paid for, whatever is left is yours to spend on upgrades.

Keep a simple list with three columns: budgeted, committed (orders and signed quotes) and paid. Updating it weekly shows early when a category is drifting, while there is still time to adjust elsewhere — for example by choosing a different tile or postponing a non-essential item.

Painting, simple demolition and fitting click flooring are common DIY jobs that save labour costs. Electrical and gas work, structural changes and anything that needs certification should be left to qualified professionals — in many countries this is a legal requirement, and mistakes are expensive to fix.