Updated 20 September 2026
Housing cost
Every extra cost on a leftover plot has to be paid by someone. In cheaper coastal Norfolk and Fenland the bill often kills the site. In Cambridge, Hertfordshire and west Essex the same bill is loaded into the sale price. Either way, leftover land is not a cheap-homes policy.
Someone has to pay
A leftover site only becomes homes if the finished houses are worth more than the cost of building them, cleaning the ground, meeting the rules, and paying the landowner enough to sell. In the East those extra costs stack up:
- knocking down and cleaning the old use, using the official cost ranges
- building above flood level and giving up plots to drainage
- nutrient credits in Norfolk and the Stour and Orwell
- 10% more nature, often bought off-site because the plot has no spare ground
Those costs come off the land price first. Then they come off the quality of the homes. Then they come off the decision to build at all.
Two different outcomes
In Fenland, Great Yarmouth, King's Lynn and other cheaper markets, the extra bill often cannot be paid. The site stays on the list. The headline number does not change. No houses appear.
In Cambridge, south Hertfordshire and parts of Essex, prices can carry the bill. The cost does not vanish. It is paid in the house price, in fewer affordable homes, or in a smaller scheme. Reusing leftover land in those markets can make housing dearer than a planned new place that pays for roads and schools once.
What this is not
This is not an argument against cleaning dirty land. It is an argument against treating the leftover-land total as a pile of cheap, ready homes. The government has already said the lists do not hold the volume the country needs. Cost is one reason the workable slice is smaller still.
How to read the map
Cost is the one step on the walk that removes nothing. It cannot: a bill is not a boundary, and taking sites out for being expensive on top of taking them out for the flood, the ground and the nutrients that made them expensive would count the same problem twice.
What the step lights instead is the lower-value coastal and Fenland authorities, where the bill is least likely to be payable. Read it as an overlay on the other screens rather than a screen of its own. It is also the crudest tag on the map — a whole-authority proxy for a judgement that is really made scheme by scheme, on the day someone prices the works.
Questions people ask
- Why would homes on leftover land cost more?
- Demolition, cleanup, flood-safe building, nutrient credits and extra nature space are costs a clean field does not carry. If buyers will pay, they pay. If they will not, the site stays empty.
- Is this just developers talking the site down?
- The planning system already asks whether a site can actually pay for itself. The cleanup cost handbook and the nutrient and nature rules are public. Values are weakest in the same places that flood and need nutrient credits.
Where the numbers come from
- Guidance on dereliction, demolition and remediation costs — Homes and Communities Agency, 1 January 2015
- Banking on Brownfield — Lichfields, for the Land Promoters and Developers Federation, 1 June 2022. National register capacity equated to 31% of 15-year housing need, with less brownfield where demand is highest.
- Planning Practice Guidance: biodiversity net gain — Department for Environment, Food and Rural Affairs / MHCLG, 12 February 2024. 10% biodiversity net gain became mandatory for major development in February 2024.
- Nutrient neutrality advice to competent authorities — Natural England, 16 March 2022. Covers the River Wensum SAC and Broads SAC/Ramsar catchments, affecting all seven Norfolk local planning authorities.
- State of Brownfield 2025 — CPRE, 1 September 2025. Uses 2024 register data. East of England: 132,338 minimum net dwellings, of which 75,212 (57%) had planning permission.