GDV Calculator Changelog

When source data refreshes or features ship, the entry lands here first. BCIS quarterly cuts, NPPF revisions, PPG-Viability updates, SDLT / LBTT / LTT rate changes all show up here. Audit trail for the data integrity stamp on every page.

2026-06-24 - Launch (workbench v1)

Initial workbench shipped with 12 BCIS regions and 6 London borough deep-dives.
BCIS Q2-2026 build-cost bands wired in.
NPPF Dec-2025 + PPG-Viability Dec-2025 viability framing applied across the cost-line pages.
9 scheme-type presets loaded.
5-by-5 sensitivity heatmap on the hero.

2026-06-15 - BCIS Q2-2026 ingest

BCIS Q2-2026 vintage cut against Q1-2026 baseline.
Regional adjustment factors refreshed; NW remains baseline (index 100).
Conversion rate band tightened on the back of recent BCIS reporting.

2025-12-19 - NPPF Dec-2025 + PPG-Viability Dec-2025

NPPF Dec-2025 revision picked up; small-sites threshold language refreshed.
PPG-Viability Dec-2025 17.5 percent PoGDV benchmark applied across viability and developer-return pages.

BCIS General Building Cost Index Q2 2026· Q2 2026Appraisal model reviewed by Oliver Wakefield-Smith (data integrity) with chartered-surveyor (MRICS) and CTA tax review. No affiliate links.