Refurbishment is priced by its surprises, not by its drawings

There is a short answer about refurbishment risk and a useful one, and they are not the same. What follows is the useful one.

You are buying an unknown building

A new building is described completely before it is priced, while an existing one is described only as far as anybody has looked. Drawings for older buildings are frequently missing, incomplete or describe an intention that the construction departed from.

Alterations made over decades are rarely recorded, so structural interventions, removed walls and added loads appear as discoveries during the work. This is why refurbishment tenders carry larger contingencies than new build and why those contingencies are so often consumed. The useful mental model is that you are paying for information as well as for work, and cheap information is expensive later.

Intrusive survey pays for itself

Opening up floors, ceilings and a sample of the structure before pricing converts unknowns into either specified work or documented absence. It costs money before any funding is certain, which is precisely why it is the item most often cut from an early budget.

A programme that skips it will meet the same conditions on site, at a point when the contractor holds the commercial advantage. Sampling has limits, since what is found in three locations may not represent the other thirty, and this should be stated rather than glossed. The realistic aim is to narrow the range of outcomes rather than to eliminate risk, and that narrowing is what lenders need.

Hazardous materials change the sequence

Buildings of certain periods contain materials that are now regulated, and their presence changes how, when and by whom work can be carried out. Surveys for these materials are required in most countries before disturbance, and the results determine the demolition and strip-out programme. Discovery mid-programme is expensive because work stops, specialists are engaged and the area is isolated until it is cleared.

On the ground, rules and thresholds vary considerably between jurisdictions, so a process learned in one country does not transfer directly to another. This is a category where the professional advice is mandatory rather than optional, and shortcuts have consequences beyond cost.

Regulatory upgrade is triggered by extent

In many jurisdictions, once works exceed a certain scope the whole building must be brought closer to current standards. That can pull in fire safety, accessibility, energy performance and structural requirements that were not part of the original brief. The threshold creates a strong incentive to keep works just below it, which sometimes produces worse buildings than a full upgrade would.

It also means a project can become dramatically more expensive because of a decision that looked minor in the scope discussion.

Knowing where the local threshold sits before scoping is one of the highest-value pieces of early advice available.

The carbon case and the cost case diverge

Retaining a structure avoids the emissions embodied in a new frame and foundations, which is usually the largest single component. That environmental advantage does not automatically translate into a financial one, because refurbishment labour is more intensive and less predictable.

Where demolition prices lower than retention, the difference is often the value of the additional floor area a new building could achieve. Policies that require a retention option to be assessed before demolition consent change the default and add process time. Both the carbon and the cost arguments are legitimate, and conflating them weakens the case for whichever one is actually being made.

Comparisons across cities are difficult because nobody counts the same things.

Reducing the surprise

Commission the survey before the design, so the design responds to the building found rather than to the building assumed. Sequence the strip-out as an early, separately procured package, which reveals conditions while the main design can still change.

Build a risk register with named items and estimated ranges rather than a single percentage contingency, since a percentage hides what it covers. Choose a contract that shares risk explicitly, because a fixed price on an unsurveyed building simply prices the unknown at the contractor rate. None of this makes refurbishment predictable, and it moves the uncertainty into a place where it can be discussed rather than discovered.

The takeaway

Pay for the survey. It is the cheapest part of the project and it prices everything else.

The design decision is visible long after the people who made it have gone.