Market report · 7 July 2025 · 11 min read
How we value a house nobody has sold before
There are no comparables for a one-off. Here is the method we use instead, and where it is weakest.
Conventional valuation leans on comparables, and a house that is the only one of its kind has none. We build a value from three components instead: replacement cost of the fabric, a market rate for the floor area in that neighbourhood, and an authorship weighting derived from the panel’s score.
The authorship weighting is the contentious part. We publish the multipliers and version them, so an owner can see exactly what a named architect in original condition is worth in our model, and argue with it if they disagree.
Where it is weakest is at the very top. Above roughly eight million the sample thins out to a handful of transactions a year, and any model built on that few points is closer to a considered opinion than a calculation. We say so in the report rather than hiding it behind a decimal place.
Written by Mara Okonjo · Appraisal
