Three things people frequently confuse
| Question | What to check |
|---|---|
| Is the property an HMO for housing law? | Occupants, households, facilities and the applicable HMO definition or exemption. |
| Does it need an HMO licence? | Mandatory licensing and any additional or selective scheme, boundaries, conditions and current dates. |
| Can it lawfully operate in the proposed planning use? | Lawful existing use, Use Classes C3/C4 or other use, permitted development rules, signed Article 4 direction and any planning permission. |
What is a C3-to-C4 Article 4 direction?
Class C3 generally describes a dwellinghouse. Class C4 describes small HMOs occupied by three to six unrelated residents, subject to the planning-use definition. Depending on the circumstances, certain C3-to-C4 conversions may otherwise benefit from permitted development. An applicable Article 4 direction can withdraw that right in a defined area, meaning a planning application may be necessary.
Do not infer: that every Article 4 direction concerns HMOs, that the whole council is covered, or that its adoption date equals its effective date. Some directions concern unrelated building works, not HMO changes.
How to verify the address
Confirm the proposed use
Identify the existing lawful planning use, proposed number of residents and whether your proposal is a change from a C3 dwellinghouse to a C4 small HMO or involves another classification.
Find the planning authority
The postal local authority may not be the relevant planning authority in every case. Confirm the actual address and the competent planning authority.
Read the signed Article 4 direction
Check the direction instrument and confirmed maps, the class of permitted development removed, when it took effect and any exceptions. Do not treat an Article 4 map pin as legal confirmation.
Check the planning history
Look for existing lawful use, planning permissions, conditions, lawful development certificates, enforcement and changes made since the direction began.
Get a clear decision before conversion
If permitted development is unavailable or uncertain, speak to the council or a planning professional about an application, evidence and the proposal merits. Licensing checks remain separate.
Why a postcode result alone isn't reliable enough
Our screening API and the national Planning Data service may return mapped Article 4 areas at an approximate postcode centroid. That is not the property's boundary, and the national dataset is incomplete. A map hit may be unrelated to HMO use. A missing hit is not evidence of unrestricted conversion.
This is why the tool returns UNKNOWN for incomplete evidence rather than declaring an address clear. The definitive next step is checking the signed council direction and exact property circumstances.
Example: one council may have multiple directions
Ealing Council publishes directions affecting different parts of the borough, with different dates and exceptions. Reading only a council-wide summary or relying on a postcode centre could miss those distinctions. Always inspect the official Ealing direction documents and maps ↗. This example does not confirm the planning position of any specific Ealing property.
What if the house was already used as an HMO?
A lawful existing use, the timing of an Article 4 direction and any intervening change of use can materially change the question. Don't assume that a direction retrospectively makes an established lawful use unlawful or automatically permits converting back again. Review the planning history and obtain council advice or evidence of lawful use where appropriate.
Primary official references
- GOV.UK Planning Practice Guidance: when planning permission is required
- Planning Data: contributed Article 4 direction areas
- Lambeth Council: HMO-related and other Article 4 directions
- Ealing Council: HMO Article 4 directions
Then use the free HMO property checker for postcode-based research signals and our bedroom-size calculator for a separate national minimum-area assessment.