Property development glossary

Forty terms, defined the way developers actually use them. Related: our developer guides and live £/sqft data by area. Updated July 2026.

Absorption rate: The pace at which a scheme or market sells new homes, expressed as units per month. Derived from completion dates of nearby new-build sales; drives cashflow, finance cost and scheme sizing.
Achievable price: The price a unit can realistically be sold for in the current market, evidenced from comparable sold transactions rather than asking prices.
Affordable housing contribution: Homes (or payments) a developer must provide under planning policy, typically via a Section 106 agreement; reduces net GDV in appraisal.
Asking price: The advertised marketing price of a property. Not evidence of value — appraisals should use sold, completed, registered prices.
Build cost per sqft: Construction cost divided by gross internal floor area; the core cost input in a residual appraisal alongside externals and abnormals.
CIL (Community Infrastructure Levy): A fixed, published per-sqm planning charge levied by many local authorities on new floorspace; a known cost line in appraisal, unlike negotiated S106.
Comparable (comp): A sold property used as evidence of value for another. Good comps are nearby, recent (or indexed), of similar type and size, with a verified floor area.
Completion: The legal transfer of ownership; the date recorded by HM Land Registry. Off-plan sales complete months after they are agreed.
Confidence score: A measure of how trustworthy a statistical price estimate is, reflecting comp count, evidence weight and dispersion. Thin evidence should show low confidence, not false precision.
Development finance: Lending secured against a development scheme, drawn in stages against build progress and repaid from sales; priced against GDV, costs and sales-rate assumptions.
EPC (Energy Performance Certificate): A public record of a dwelling’s energy performance that also records its total floor area and habitable rooms — the floor-area source for £/sqft analysis.
Evidence radius: The distance around a site within which sold transactions are treated as evidence; typically 1–3 miles, boundary-checked against real market divides.
Floor area (GIA/total): The internal area of a dwelling. EPC certificates record total floor area in square metres (×10.764 for sqft); consistency of definition matters when applying £/sqft.
GDV (Gross Development Value): The total expected sales revenue of a completed scheme: achievable £/sqft × planned floor area, summed across the unit mix.
Ground rent: A periodic charge on leasehold property. Effectively abolished for new residential leases in England and Wales since 2022.
Habitable rooms: The EPC’s count of living rooms and bedrooms (kitchens and bathrooms excluded); used to estimate bedroom counts, which should always be flagged as estimates.
HPI (House Price Index): The official UK index of house-price levels, published monthly. Used to restate historic sold prices in today’s money (indexation).
Incentives: Discounts or extras (stamp duty paid, upgrades, part-exchange) used to support new-build sales; largely invisible in public data, so registered prices can overstate net achieved prices.
Indexation: Adjusting a historic sold price by the ratio of today’s HPI to the HPI at sale date, so sales from different years can be compared fairly.
Land Registry (HM): The official register of property ownership and transactions in England and Wales; its Price Paid Data records price, date, address, type, tenure and the new-build flag for every sale.
Leasehold: Ownership of a property for a fixed term under a lease, common for flats; pricing reflects lease length, service charges and management quality.
Market boundary: A line across which buyer behaviour changes (catchment, transport, flood zone). Evidence radii that straddle one mix two different markets.
New-build flag: The Land Registry’s official Y/N field marking the first sale of a newly built home — the authoritative way to separate new-build from resale evidence.
New-build premium: The percentage by which local new-build £/sqft exceeds resale £/sqft; varies widely by area and should be measured from local evidence, not assumed.
Off-plan sale: A sale agreed before construction completes. Registered months later at completion, which lags the true point of demand.
Optioned land: Land controlled via an option agreement — a fee for the right (not obligation) to purchase, typically exercised on planning consent.
Outlier trimming: Removing extreme values (e.g. £1 transfers, data errors) before averaging, commonly the top and bottom 2%; prevents a handful of records distorting an area’s statistics.
Overage: A contractual right for a land seller to receive extra payment if the buyer later achieves a better consent or higher value than assumed at sale.
Planning risk: The probability that consent is refused, delayed or degraded; priced into unconditional land offers via probability-weighting or transferred via conditional structures.
Plot ratio / density: Buildable floorspace relative to site area. With £/sqft and absorption, one of the three levers of land value per acre.
Price paid data: The Land Registry’s public dataset of every registered sale in England and Wales since 1995.
Price per square foot (£/sqft): Sold price divided by internal floor area; the standard unit of comparison in development appraisal because it transfers across sizes and types.
Profit on GDV: Developer profit expressed as a percentage of gross development value; lenders typically expect roughly 17.5–25% on speculative residential schemes.
Residual land value: What a developer can pay for land after subtracting build costs, fees, finance and target profit from GDV; the maximum rational bid.
Resale: Any sale of a property after its first sale — the counterpart to new-build in the Land Registry’s flag.
Section 106 (S106): A negotiated legal agreement attached to a planning consent obliging contributions (affordable housing, infrastructure); a scheme-specific appraisal cost.
Sensitivity analysis: Re-running an appraisal with adverse inputs (lower GDV, higher costs, slower sales) to see whether the deal survives; standard lender practice.
Tenure: The legal basis of ownership — freehold or leasehold — recorded for every Land Registry sale and relevant to comparability.
Unit mix: The combination of house types and sizes on a scheme; evidence on per-type rates, demand depth and absorption should drive it.
Yield (investor): Annual rent as a percentage of price; governs investor demand for flats and build-to-rent, and thus part of absorption in flat-heavy markets.