Southwark SE1 GDV Calculator

Southwark SE1 GDV 840 to 1350 £/sqft. Borough CIL 350 £/sqm. Mayoral CIL2 zone Z1. Workbench prefills with London BCIS Q2-2026 build cost and the borough mid-band GDV.

GDV and CIL working numbers

  • GDV: 840 to 1350 £/sqft
  • Mid GDV: 1050 £/sqft
  • Borough CIL: 350 £/sqm
  • Mayoral CIL2: Z1

Southwark CIL Old Kent Road zone. 35 percent affordable threshold above 10 units.

Local context

  • SE1 covers Borough, Bermondsey, Elephant and Castle.
  • Southwark CIL Old Kent Road zone plus Mayoral CIL2 Zone 1.
  • BTR yields hold at 4.5 to 5.0 percent net initial yield on prime SE1 stock.
  • 35 percent affordable threshold applies above 10 units.

Open the workbench

Inputs
MAX LAND BID£3,406,174At 20% profit on cost, 9 units, 950 sqft GIA each.
MARGINAL
GDV£7,630,875
Build cost£2,422,678
Prof fees£290,721
s106/CIL/BNG£220,500
Contingency£220,042
Finance interest£224,718
Target profit£675,732
Total costs (excl land)£3,378,660
Senior debt @ LTGDV£4,960,069
PoC12.5%
PoGDV11.1%
LTC73.1%
Sensitivity (PoC %)
Build -5%Build +5%Build +10%Build +15%Build +20%
GDV -15%13%14%15%15%16%
GDV -10%13%14%14%15%15%
GDV -5%13%13%14%14%14%
GDV 0%12%13%13%14%14%
GDV +5%12%12%13%13%14%

Cells show profit-on-cost percentage at each GDV stress / build-cost shock pair. Cells below your target PoC turn amber-warm; cells below 10 percent abort.

Mayoral CIL2· Mayoral CIL2 in forceAppraisal model reviewed by Oliver Wakefield-Smith (data integrity) with chartered-surveyor (MRICS) and CTA tax review. No affiliate links.