Use Classes Order 1987
The Town and Country Planning (Use Classes) Order 1987 groups buildings by their function. A change between use classes generally requires planning permission; a change within a class does not. For landlords, the critical classes are C3 (dwelling house), C4 (small HMO), C5 (short-term let) and sui generis (large HMO).
C3 Dwelling House and C4 Small HMO
C3 covers single-family occupation and small households. C4 covers houses occupied by 3–6 unrelated people sharing facilities. GPDO 2015 Part 3 Class L grants a permitted development right to change between C3 and C4 without planning permission — unless the LPA has removed it with an Article 4 Direction. Many LPAs in areas of high HMO concentration have Article 4 Directions removing the C3↔C4 PD right, requiring full planning permission.
- Article 4 LPAs removing C3↔C4 PD right include Oxford, Cambridge, Bristol, Manchester, Leeds, Newcastle, York, Nottingham, Southampton, Portsmouth, Brighton, and Bournemouth
- Conversion of C3 to C4 without planning where Article 4 applies is a breach of planning control
- LPAs can enforce for up to 4 years (operational development) or 10 years (change of use)
C5 Short-Term Let
Class C5 was introduced from 26 February 2024 by SI 2024/244 under LURA 2023. It covers dwellings let for short periods of up to 31 consecutive days. A PD right allows change between C3 and C5 without planning permission, but LPAs in tourist hotspots can remove it with an Article 4 Direction. St Ives, parts of Cornwall, the Lake District, and South Hams have introduced or are introducing Article 4 Directions for C3↔C5 changes.
Sui Generis — Large HMO
An HMO occupied by 7 or more unrelated people is sui generis — it falls outside any use class. Planning permission is always required to create a large HMO regardless of any Article 4 Direction. There is no PD right for C3 to sui generis conversion. LPAs can also impose conditions limiting the proportion of HMOs in a street or area.
Class Q — Agricultural to Residential PD
GPDO 2015 Part 3 Class Q allows conversion of agricultural buildings to up to 5 dwellings, capped at 865 sqm total (each up to 465 sqm), where the building has been in agricultural use for at least 10 years. Prior approval is required — the LPA assesses transport, noise, contamination, flooding, design, natural light, and protected species. Class Q does not apply in National Parks, AONBs, or where the building was erected under agricultural PD rights after 20 March 2013.
Class MA — Commercial to Residential PD
GPDO 2015 Part 3 Class MA allows conversion of Class E commercial premises (offices, retail, cafes) to C3 residential where the building has been vacant for at least 3 consecutive months. Prior approval is required. The building must not exceed 1,500 sqm and must not be in an AONB, National Park, or SSSI. Class MA applies in Conservation Areas from July 2021 with an additional condition that the development must not reduce Class E floorspace in an area where the LPA has demonstrated it is needed.