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Building Safety Levy in Hounslow
Hounslow is the 21th most expensive of 298 English collecting authorities. The greenfield area rate is £58.29/m², halved to £29.15/m² where ≥75% of the red-line boundary qualifies as previously developed land. BSL commences 1 October 2026 and is collected by Hounslow at building-control and commencement stages.
Rates for Hounslow
| Rate type | £ per m² GIA | Applies when |
|---|---|---|
| Greenfield (standard) | £58.29 | Less than 75% of site is previously developed land |
| Brownfield (PDL discount) | £29.15 | ≥75% of site is previously developed land (any building since July 1948, excluding agriculture) |
Source: Schedule 3, Building Safety Levy (England) Regulations 2025, effective 1 October 2026.
Example scheme costs in Hounslow
| Scheme | Total chargeable GIA | Greenfield levy | Brownfield levy | PDL saving |
|---|---|---|---|---|
| 10 dwellings at 85 m² each (small infill) | 850 m² | £49,546 | £24,778 | £24,769 |
| 50 dwellings at 100 m² each (typical phase) | 5,000 m² | £291,450 | £145,750 | £145,700 |
| 100 dwellings at 95 m² each (mid-size scheme) | 9,500 m² | £553,755 | £276,925 | £276,830 |
| 200 dwellings at 90 m² each (major development) | 18,000 m² | £1,049,220 | £524,700 | £524,520 |
All examples assume 100% residential with no communal-area adjustments. Real schemes will differ based on communal floorspace, PBSA bedspaces, and exemptions.
The 50% brownfield discount
For a typical 50-dwelling scheme in Hounslow, successfully evidencing previously developed land status saves £145,700 in levy. That’s the whole point of the PDL evidence workflow — the statutory definition (any building on the site since 1 July 1948, excluding agriculture) is broader than the local brownfield register, and most sites qualify in full or in part when historic OS maps and aerial imagery are reviewed.
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Submitting your BSL information to Hounslow
BSL submissions happen in two stages: (1) at your building-control application, and (2) at your first commencement notice. Hounslow has five weeks from your commencement notice to assess and issue a liability notice. Any GIA or PDL discrepancy can delay commencement.
BSL Prep extracts chargeable GIA from your architectural PDFs, compiles the PDL evidence pack, and produces the submission proforma for Hounslow in one click. See pricing →