Room sizes + kitchen + bathroom + communal + heating
HMO Standards 2018 mandatory minimums (Housing Act 2004 s65 + Licensing of HMOs (Mandatory Conditions) Regs 2018): (1) Bedrooms — Single 6.51m² (10+); double 10.22m² (both 10+); below 4.64m² unfit; 4.64–6.51m² child under 10 only. Useable area excludes sub-1.5m headroom + chimney breast + en-suite + fixed wardrobe. (2) Kitchen — 5m² minimum + cooker ratio: 5 occupants share 1; 6+ need 2 cookers OR commercial 6-ring + 2 ovens. Worktop 0.5m linear per occupant. Fridge 30L per occupant; freezer 25L. Sink + drainer + hot/cold water. Wall + base storage. Extract 30L/s (Part F). FD30 kitchen door to lobby. (3) Bathroom + WC — 1 bathroom (bath OR shower + WHB) per 5 occupants up to 4; from 5 typically 2 bathrooms required + separate WC if 6+ occupants. Each bathroom 3m² + extract 15L/s (Part F) + non-slip floor. (4) Communal living — required above 5 occupants: 11m² + 1.5m²/occupant above 5 (e.g. 8-occupant HMO needs 15.5m²). Can combine with kitchen if total meets sum. (5) Heating + hot water — 18°C bedrooms + 21°C living + bathroom; hot water 24/7; thermostatic control; annual CP12. (6) Lighting — natural to all habitable rooms (windows ≥10% floor); artificial + emergency to escape routes ([[hmo-fire-safety-compliance-london]]). (7) Refuse + cycle — secure refuse store (3 wheelies for 6-bed); cycle 1 secure space per occupant (Sheffield stand or Cycle Hoop); recycling per borough.
Borough variations + LPA standards + Builderr design margin
Borough overlays via HMO licence conditions / local plan: Tower Hamlets HMO Standards 2023 (9m² single + 14m² double — strictest London; 1 bath per 4 from 6+; communal + kitchen separate from 7+); Newham Local Standards 2024 (7.5m²/11m² + ensuite required 8+ occupants); Hackney HMO Policy 2021 (8.5m² single combined with ensuite; 12m² double; 12m² communal + 1.5m²/occupant from 5; sprinkler conditioned 7+); Camden Local Standards 2022 (7m²/10.5m²; 1 bath per 4; 2 cycle/occupant; refuse 1.5m²/occupant); Westminster HMO Standards 2020 (7.5m²/11m²; 24/7 manager + CCTV common areas); K&C HMO Policy 2022 (8m²/12m²); Islington HMO Standards 2023 (7m²/10.5m²); Lambeth HMO Policy 2024 (7m²/10.5m²). Always check LPA HMO standards before design. Pre-app advice (£280–£540) reveals borough position. Builderr design default — exceed minimum by 10–15% margin: singles 7.5m²; doubles 11.5m²; communal 13m² + 1.8m²/occupant; bathroom 1 per 4; cycle 1.5 per occupant; refuse 2m²/occupant. Cost premium 5–12% (£4,800–£18,500 on 4–8 bed) paid back via faster licence + fewer conditions + tenant retention. Common design fails London 2026: undersized bedrooms (chimney breast + alcove not deducted = inspection fail); undersized kitchen 6+ occupants (single 4-ring insufficient); shared bathroom 6+ without 2nd WC (queue + complaint); no communal space (all areas converted = refusal); no refuse storage (rubbish = ASB complaint + breach). See [[hmo-licensing-london-cost-and-process]] + [[minimum-room-sizes-hmo-london-2026]] + [[converting-house-to-hmo-london-planning]].
