Planning & Budgeting — 3 min read — February 17, 2026
The Most Underestimated Cost in a Refurbishment
Budgeting is the backbone of any successful project. We explain preliminaries: the hidden site costs that catch London homeowners off guard.
Somewhere between finalising your kitchen specification and approving the bathroom tiles, a line item will appear on your contractor's quote for something called preliminaries. It will represent a significant portion of your total build cost, and it will not include a single tile, tap, or square metre of flooring. Clients who have spent weeks researching worktop materials and comparing appliance specifications tend to find this figure genuinely shocking, which is understandable, and which is also the reason it deserves a proper explanation.
The Infrastructure of Construction
Preliminaries — prelims, in the industry shorthand — cover everything required to establish and maintain a functioning building site. The term is deceptive because it implies something that happens before the real work, when in practice it describes a continuous overhead that runs for the entire duration of the project. Protective coverings for existing floors and staircases, dust barriers between active work zones and habitable rooms, temporary lighting, site signage, welfare facilities for the trades, temporary power distribution when the existing electrics have been disconnected, scaffolding, skip hire, waste removal, and the daily supervision that keeps the whole operation coordinated and legally compliant. On a typical London refurbishment, prelims account for 10 to 15 per cent of the total build cost.
The reason this figure catches people off guard is that every other line on the quote corresponds to something tangible in the finished home. Prelims correspond to the process of getting there, and once the project is complete, the evidence of that expenditure has been entirely removed. The scaffolding is gone. The skips are gone. The dust barriers have been taken down. You are left with a beautiful house and no visible trace of the infrastructure that made it possible, which makes the cost feel retrospectively abstract in a way that a new kitchen does not.
Period Properties and the Cost of Protection
In a Victorian or Edwardian townhouse with original features worth preserving — encaustic floor tiles, decorative plasterwork, timber staircases — the protection element of prelims can represent a significant portion of the total on its own. This is not overcaution. A cracked original mosaic floor or a damaged ceiling rose means specialist restoration at rates that can exceed the cost of entire rooms elsewhere in the project. The quality of site protection is one of the more reliable indicators of a contractor's competence, and it is worth scrutinising in any quote, because the cost of doing it properly is always less than the cost of repairing what happens when it is done cheaply.
The Line Items That Accumulate
Scaffolding on a multi-storey London townhouse is a substantial cost in itself, with additional weekly charges if the programme overruns. Council scaffolding licenses in central boroughs add time and cost to the process. Skip hire across a full refurbishment accumulates quickly, with permit charges on top in areas with parking restrictions, which in London is most areas. Temporary services — welfare facilities, temporary water, temporary power distribution — are unglamorous and entirely non-negotiable. Site management and supervision represent real person-hours of coordination: organising deliveries, managing access, maintaining security, and ensuring that work is built as specified rather than as interpreted. These costs are built into every contractor's pricing. They are not profit margin in disguise. They represent the actual operational cost of running a building site in a dense, regulated, expensive city.
Calibrating the Budget
The practical consequence of prelims is that the budget available for finishes, fixtures, and fittings is meaningfully smaller than the total project budget. Knowing this early — ideally at feasibility stage, before any design work begins — is the difference between a specification that aligns with what the project can actually afford and one that needs to be painfully value-engineered halfway through construction when the costs become real. A well-prepared feasibility study breaks prelims out as a visible line so that the remaining budget can be allocated honestly. The alternative is the slow, demoralising discovery that the finishes you designed around are no longer within reach, at a point in the project when changing direction is expensive and changing nothing is worse.