HMO planning permission London — Article 4 directions by borough

The C3-to-C4 shortcut is gone across much of London — check the borough, then the address.

By Planning Permission Checker Editorial · Reviewed by Savas Bulduk MRICS, Director, Hampstead Chartered Surveyors & Building Consultancy — RICS-regulated (Firm Reg. 923064)

For years, converting a single dwelling house (use class C3) into a small house in multiple occupation (use class C4 — typically three to six unrelated occupants sharing facilities) could proceed as permitted development in many places. Across London that shortcut has been systematically removed: borough after borough has made Article 4 directions requiring a full planning application for small HMO conversions. If you are buying, refinancing or converting for shared occupation, the planning route is now the rule, not the exception.

What changed: Article 4 and the C3→C4 route

An Article 4 direction does not ban HMOs. It withdraws the national permitted-development right for a defined area so the change of use needs planning permission and can be tested against local housing, amenity and concentration policies. Small HMOs (C4) are the usual target; larger HMOs (sui generis, seven or more occupants) already needed permission. Always read the direction's schedule — some are borough-wide, some cover wards or conservation streets only.

What the official geometry shows (and what it misses)

Planning Permission Checker's London Article 4 Coverage Index grid-samples every borough against planning.data.gov.uk geometry. Nine boroughs show at least one direction whose footprint is effectively borough-wide (a geometric signal, not a free-text classification of the schedule): Camden, Westminster, Kensington and Chelsea, Barnet, Brent, Enfield, Waltham Forest, Hillingdon, and Barking and Dagenham. In several of those cases the borough's own commentary and Article 4 notes identify the controlling instrument as HMO-related or as a stack that includes HMO control — but the index never invents a direction title from a percentage alone.

Nineteen of the 33 London boroughs currently have no Article 4 geometry at all in the national dataset. That is a dataset-coverage gap, not proof those boroughs lack HMO directions. Many councils operate significant HMO Article 4s that are not yet in the national layer — including examples documented on this site from each borough's own register (for instance Enfield since October 2013, Waltham Forest since September 2014, Newham since July 2013, Redbridge since December 2019, Bexley since September 2017, Sutton from February 2025, and Lewisham in two stages through January 2024). Always confirm on the council's Article 4 pages as well as any map-based check.

Borough patterns worth knowing

Outer and north-east boroughs were early and thorough on small-HMO Article 4s — Enfield, Waltham Forest, Newham, Redbridge, Bexley, Havering and Barking and Dagenham all document borough-wide (or dual-direction full-coverage) HMO control in their published notes.
West and north-west boroughs have followed: Brent (from November 2022), Ealing (October 2024), Hounslow (2022 across most of the borough), Hillingdon (borough-wide HMO direction among a wider Article 4 stack).
Inner boroughs often stack HMO control with conservation-area design directions and commercial-to-residential controls — Southwark's many directions, for example, are largely pubs and frontages rather than householder extensions, while tower-centre commercial protection is common in Tower Hamlets and Kingston.
A mapped '100% coverage' borough is not automatically 'no PD for extensions' — check which right each direction removes.

How to check before you buy or convert

Run the postcode through the free area report for live conservation-area and Article 4 geometry where the national dataset holds it.
Open the council's Article 4 register for that borough — especially if the national map shows 'not held' or you are planning a C3→C4 change.
Confirm use class, occupancy number (C4 vs sui generis) and any additional licensing regime — planning permission and HMO licensing are separate tracks.
If the property is a flat or maisonette, permitted development for change of use does not help you the way it once did for houses; freeholder consent and lease terms sit on top.
Budget for a full planning application and evidence on amenity, waste, parking and concentration where local policy requires it.

If permission is refused

Refusal is usually about concentration, amenity, or conflict with local HMO and housing mix policies — not a blanket moral judgment on shared living. Read the decision notice, check whether a revised scheme or a different occupancy model fits policy, and consider appeal only with professional advice. Unauthorised occupation as an HMO where permission is required can attract enforcement.

Check the address against official conservation-area and Article 4 geometry, then confirm HMO directions on the council register before you commit to a conversion.

Check an address

Do I need planning permission to create a small HMO in London?

In most London boroughs, yes — borough-wide or wide-area Article 4 directions have removed the old permitted-development right to convert a house (C3) to a small HMO (C4). Confirm the direction that applies at the specific address on the council's Article 4 register; do not assume from the borough name alone if the national map shows a gap.

What is the difference between C4 and a large HMO?

C4 covers small HMOs of three to six unrelated occupants sharing basic amenities. Larger shared houses (typically seven or more) are usually sui generis and already needed planning permission before the recent wave of small-HMO Article 4s.

Does an HMO Article 4 stop me extending my own home?

Not by itself. HMO directions target change of use to shared occupation. Rear extensions, lofts and similar householder works are controlled by other PD rules, conservation areas and any separate householder Article 4 directions.

Why does the national map miss some boroughs?

Nineteen London boroughs currently have no Article 4 geometry in planning.data.gov.uk even though many operate real directions. Treat 'not held' as a data gap and verify on the council's own pages — the same honesty rule used across this site.

Where can I see borough-by-borough coverage?

The London Article 4 Coverage Index ranks mapped coverage for all 33 boroughs from official geometry, with downloadable CSV/JSON and an explicit blended-metric caveat. Pair it with the householder approval-rate league table if you are comparing how strict boroughs look on decision outcomes.

HMO planning permission and Article 4 directions in London