What is the most expensive part of a house renovation?
Structural work and building services — walls, steels, foundations, rewiring, plumbing and heating — typically account for 40 to 50 percent of a full renovation budget. Kitchens and bathrooms feel more expensive because you choose them, but they are usually a smaller share.
The expensive parts of a renovation are the parts you cannot see when it is finished. Removing a structural wall requires a designed steel beam, padstones, temporary support, building control inspection and substantial making good — £4,000 to £8,000 for a single opening. Underpinning, new foundations or a basement dig run into tens of thousands before anything is visible.
Services are the other half of the invisible cost. A full rewire of a Fulham terrace is £8,000 to £14,000 including chasing and making good, and the making good is often half of that on a solid-walled Victorian house. A complete replumb with a new heating system is £8,000 to £15,000. Neither changes how a single room looks.
Kitchens and bathrooms are where the psychology misleads. A £20,000 kitchen feels enormous because you stand in a showroom choosing it, but on a £250,000 whole-house renovation it is 8 percent of the budget. The steels, the rewire and the plastering that nobody chooses are collectively three times that.
There is a practical implication. When a quote comes in over budget, the instinct is to downgrade the kitchen — but that saves less than expected and costs you the thing you interact with daily. The larger savings are almost always in scope: doing three rooms instead of five, keeping a wall, phasing the loft into a later year. We would rather have that conversation openly than quietly specify cheaper materials.
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