A home renovation budget only works if it has a contingency line above 15%, a fixed order of priorities, and a number attached to living costs during the work. Most budgets fail not because people guess wrong on paint, but because they never plan for the three things above.
Set the number in three passes, not one
Pass one: the wish list total. Add up everything you want, at the high end of every range, with no editing. This number tells you the ceiling of the project as imagined.
Pass two: the must-have total. Strip the wish list to what fixes something broken or unsafe, plus whatever the sale or livability of the place depends on. This is usually 40-60% of pass one.
Pass three: the funded total. What you can actually spend, from savings plus whatever financing you’re comfortable with. Compare it against pass two. If funded is below must-have, the project needs phasing, not more scrimping on paint colours — see the guide on renovating in phases if that’s where you land.
Where the money actually goes
| Category | Typical share of total budget | Notes |
|---|---|---|
| Labour | 40-55% | Rises sharply once plumbing or electrical is involved |
| Materials | 25-35% | Flooring and cabinetry dominate this |
| Fixtures and fittings | 10-15% | Taps, lighting, hardware, appliances |
| Design and permits | 3-8% | Skipped by DIY projects, mandatory for structural ones |
| Contingency | 15-25% | Non-negotiable, see below |
| Living costs during work | 2-5% | Storage, takeaway, laundromat, short-term rental |
The contingency line is not optional
A contingency fund isn’t padding, it’s the part of the budget that pays for what the walls were hiding. Rewire that turns out undersized. A subfloor that’s rotten under three layers of old vinyl. A structural beam that isn’t where the plans say.
Set contingency as a percentage of the must-have total, not the wish list, and hold it in a separate account you don’t look at until something goes wrong. If nothing goes wrong, it becomes budget for the wish-list items you cut in pass two.
The order that protects the budget
- Structural and systems first. Roof, foundation, plumbing, electrical, insulation. Nothing visible matters if these fail.
- Layout changes second. Moving a wall or a door is cheapest before finishes go in, and gets exponentially more expensive after.
- Fixed finishes third. Flooring, tiling, cabinetry. These set the palette everything else responds to.
- Furniture and decor last. The cheapest category and the easiest to defer if the budget is tight by this point.
Doing this in reverse order is the single most common way a renovation budget blows up: people buy the sofa in month one and discover the wiring problem in month four with no money left.
A worked example: €35,000 kitchen and bathroom refresh
| Line | Amount |
|---|---|
| Kitchen: cabinetry, worktop, appliances, plumbing | €16,000 |
| Bathroom: retiling, fixtures, waterproofing | €9,500 |
| Electrical updates (both rooms) | €2,800 |
| Design fee | €1,200 |
| Contingency (20% of the above) | €5,900 |
| Living costs (6-week project) | €900 |
| Total | €36,300 |
Notice contingency is the second-largest line after the kitchen itself. That’s normal, not a sign of bad planning.
Where budgets quietly leak
- Scope creep between quote and start. “While we’re in there” additions rarely get re-budgeted before they’re agreed to.
- Delivery and installation fees left off supplier quotes, especially for large appliances and stone worktops.
- VAT or sales tax applied inconsistently across quotes, making comparisons look closer than they are.
- Skipping a proper cost estimate before committing to a look. Deciding on a finish before pricing it means re-deciding later under time pressure.
For cosmetic changes specifically, check what it actually costs to paint a room before you fold painting into a bigger renovation line, since it’s often cheaper done separately and early.
Try it yourself
Homie’s Cost Estimate add-on takes a photo of your room and gives you a broken-down range for the redesign it generates, in the same categories as the table above. Run it against a few room options before you commit to a scope, so pass two of your budget is based on real numbers instead of guesses. Try Homie on the room you’re most unsure about.