Prior approval is one of the most commercially significant planning instruments available to property developers and landlords. The route from empty office to residential flat, or from redundant barn to country dwelling, without the delay and uncertainty of a full planning application represents a substantial reduction in development risk. The current Class MA route (for Use Class E — commercial, business and service — premises) has been the primary driver of office-to-residential conversions since the demise of the old Class O route. Class Q continues to deliver barn and agricultural building conversions across rural England. Understanding the scope, limitations, and procedural requirements of each prior approval class is essential for any landlord or developer considering a conversion project.
Class MA — Commercial to Residential Prior Approval
Part 3, Class MA of the GPDO 2015 (as amended by the Town and Country Planning (General Permitted Development) (England) (Amendment) Order 2021) permits the change of use of a building (and any associated operations) from Use Class E (commercial, business and service) to Use Class C3 (dwellinghouse). Key eligibility conditions: (a) The building must be in Use Class E: the building must have been in Use Class E use for a continuous period of at least 2 years immediately before the date of the application; buildings that were in Use Class E use before September 2020 (when Class E replaced the old A1, A2, A3, B1 uses) count for the 2-year period; (b) The building must have been vacant: the building must have been vacant for at least 3 consecutive months immediately before the date of the prior approval application; this prevents the conversion of operational commercial premises and ensures the route is used for buildings with no viable commercial future; (c) Floorspace limits: a single Class MA application covers up to 1,500 sq m of commercial floorspace; above this limit, a full planning application is required (there is no maximum number of dwellings); (d) Excluded areas: Class MA is not available in certain protected areas including sites of special scientific interest (SSSIs), safety hazard areas, military explosives storage areas, or where the LPA has made an Article 4 Direction removing Class MA permitted development rights; (e) The specified matters: the LPA can only consider: transport and highways; contamination risks; flood risk (including groundwater flooding); noise from commercial premises that could affect the residential use; the impact on natural light in habitable rooms; and the provision of education, health, and transport services in the area; the LPA cannot refuse prior approval on grounds of: loss of employment space; affordable housing requirements; design of the interior; or general planning policy; (f) External appearance: where works are required (new windows; re-roofing; new entrance) the LPA may impose conditions on the external appearance of the building; this is separate from the prior approval decision on the specified matters.
- 2-year Use Class E period: the building must have been in Use Class E use continuously for at least 2 years immediately before the application; pre-September 2020 use in the old A1, A2, A3, or B1 classes counts towards the 2-year period
- 3-month vacancy requirement: the building must have been vacant for at least 3 consecutive months immediately before the application date; this is a hard condition — evidence of vacation date is essential
- 1,500 sq m cap per application: the maximum commercial floorspace in a single Class MA application is 1,500 sq m; no limit on the number of dwellings created within this floorspace
- LPA cannot refuse on general planning grounds: loss of commercial jobs; affordable housing requirements; design quality of the conversion — none of these are within scope for prior approval under Class MA
- Article 4 Directions can remove Class MA: LPAs in high-demand office districts (City of London; Canary Wharf; central Manchester) have made Article 4 Directions removing Class MA permitted development rights to protect commercial floorspace; check before applying
Class Q — Agricultural Buildings to Residential (Barn Conversions)
Part 3, Class Q of the GPDO 2015 permits the change of use of an agricultural building (and any associated operations) to Use Class C3 (dwellinghouse). This is the primary planning route for barn conversions in rural England. Key eligibility conditions: (a) Agricultural use requirement: the agricultural building (or the agricultural unit as a whole) must have been in use for agriculture (or have been last used for agriculture) on or before 20 March 2013; this cuts off the prior approval route for buildings constructed after 20 March 2013 for agricultural purposes (though buildings on the unit constructed before that date may still qualify); the agricultural building must have been part of an established agricultural unit — not a building newly constructed and then notionally used for agriculture; (b) Number of dwellings: up to 5 dwellings can be created from a single agricultural unit under Class Q; the 5-dwelling limit is across all Class Q developments on the unit — previous Class Q conversions count towards the limit; (c) Floorspace: the total cumulative residential floorspace from Class Q conversions on the agricultural unit must not exceed 1,000 sq m; within this, 'larger homes' (above 100 sq m each) are limited to 3, and dwellings of between 100 sq m and 465 sq m each can be created; (d) Structural integrity: the key practical test is whether the existing building is capable of conversion — the courts have held that Class Q only permits 'conversion' of an existing structure, not wholesale demolition and rebuilding (Hirose Electrical UK Ltd v Secretary of State [2021]); the building must be capable of functioning as a dwellinghouse with its existing structure and envelope retained; adding a new roof, new glazed walls throughout, and new cladding that effectively replaces the barn structure has been refused on this basis; (e) The specified matters: the LPA can only consider: transport; noise; contamination; flood risk; whether the building is capable of functioning as a dwellinghouse; location or siting of the building; and the design or external appearance of the building (the last two apply only where building operations are proposed); (f) Permitted development rights after conversion: once an agricultural building is converted to residential under Class Q, the resulting dwelling has the benefit of the standard householder permitted development rights (Class A extensions, loft conversions, etc.) — subject to any conditions imposed by the LPA.
- Agricultural use before 20 March 2013: the agricultural building must have been in agricultural use (or part of an agricultural unit last used for agriculture) before 20 March 2013; new barns built and used solely after this date do not qualify
- 5-dwelling limit per agricultural unit: the total number of Class Q conversions from any one agricultural unit cannot exceed 5 (combining all Q(a) and Q(b) applications); this is a cumulative limit across the whole unit
- 1,000 sq m total residential floorspace: the combined residential floorspace from all Class Q conversions on the agricultural unit cannot exceed 1,000 sq m; individual dwellings cannot exceed 465 sq m
- Conversion, not rebuilding: Class Q permits the conversion of an existing structure — not demolition and reconstruction; the barn must be structurally capable of housing a dwelling in its existing form; a building that requires wholesale reconstruction is not eligible
- LPA can refuse on design: unlike Class MA, the LPA can consider the design and external appearance of the conversion under Class Q — conditions on materials and fenestration are common
The Prior Approval Application Procedure and the 56-Day Default
The prior approval application procedure applies to all prior approval classes (Class MA, Class Q, and others). Key procedural points: (a) The application: prior approval applications are submitted to the LPA on Form 1 (for lawful development certificate) or via the Planning Portal; the application must include: the description of the development; the address; a site plan; a floor plan showing the proposed residential layout; and evidence of the specified matters (transport statement; contamination report; flood risk assessment; noise assessment; natural light calculations; structural survey for Class Q); (b) The 56-day determination period: the LPA has 56 days from the date of receipt of a valid application to: (i) grant prior approval; (ii) refuse prior approval (on the grounds that one or more of the specified matters raise a problem that cannot be mitigated); or (iii) grant prior approval subject to conditions; if the LPA does not make a decision within 56 days, the prior approval is deemed to be granted by default and the development can proceed; (c) The validity of the application: the 56-day clock only runs from the date the application is 'valid' — the LPA must first confirm that the application is complete and valid; an LPA that returns the application as invalid (citing incomplete information) restarts the 56-day clock; landlords should ensure the application is complete and evidenced before submission to avoid delays; (d) Conditions on prior approval: the LPA can impose conditions on the prior approval relating to the specified matters — for example, a condition requiring the implementation of noise mitigation measures; conditions must relate to the specified matters only; conditions on internal layout, room sizes, or affordability are not permitted; (e) Using the prior approval for planning permission: where the prior approval is granted, the landlord can use it (with any conditions) to proceed with the conversion; separate planning permission may be required for external works (new windows, facade alterations) beyond those covered by the prior approval.
- 56-day default: if the LPA does not determine the prior approval application within 56 days of the valid application, the prior approval is deemed granted; a landlord who records and evidences the 56-day period can proceed without an LPA decision
- Application must be valid: the 56-day clock only runs from a valid application; ensure all required documents (floor plans; supporting assessments) are included at submission; an invalid application resets the clock
- Conditions limited to specified matters: the LPA can only impose conditions relating to the specified matters (transport; contamination; flood risk; noise; natural light); conditions on internal design, room sizes, or affordable housing are not permitted
- Three-year implementation period: once prior approval is granted (or deemed granted), the development must commence within 3 years; failure to commence within 3 years means the prior approval lapses and a fresh application is required
- External works may need separate permission: where the conversion requires external alterations (new windows; cladding; roof works) beyond those inherent in the conversion, those works may require a separate planning application or householder prior approval
Other Prior Approval Classes Relevant to Landlords
In addition to Class MA and Class Q, the GPDO 2015 includes several other prior approval classes relevant to property landlords: (a) Class A — Extensions to residential dwellings (larger home extension): householders can extend a detached or semi-detached dwellinghouse beyond the standard permitted development limits (4m rear extension for detached; 3m for other houses) under a prior approval scheme; the neighbour consultation scheme requires the LPA to notify neighbours and the extension is only permitted if no neighbour raises a reasonable objection; (b) Class AA — Additional storeys on existing buildings: permits the addition of up to 2 storeys to an existing detached house (up to 3 storeys above original ground level) or 1 storey to a terrace or semi-detached house; prior approval is required; the LPA assesses: impact on the amenity of adjoining occupiers; the external appearance; natural light; transport; noise; air traffic; (c) Class AB — New flats above existing shops and offices: permits the addition of up to 2 new flats above an existing building in Use Class E or F2 (local community) use via prior approval; a significant route for creating new residential units above shops and commercial premises without full planning permission; (d) Class N — Casinos and amusement centres to residential: permits the change of use of a casino or amusement park use to Class C3 residential via prior approval; (e) Class P — Storage and light industrial to residential: change of use from B8 (storage or distribution) or B2 (general industrial) to C3 residential via prior approval; this route can be used for some warehouse conversions to residential where the building is in B8 use (not Use Class E light industrial — which is covered by Class MA).
- Class AA (additional storeys): adds up to 2 storeys to a detached house or 1 storey to a terrace or semi via prior approval; the LPA assesses amenity impact and external appearance; widely used for residential extensions within the planning context
- Class AB (new flats above shops): up to 2 new flats above Class E or F2 buildings via prior approval; a cost-effective route to creating residential units from underused airspace above commercial premises
- Class P (storage to residential): change of use from B8 storage/distribution to C3 residential via prior approval; not the same as Class MA (which is Use Class E); check the current use class of any warehouse or storage building before choosing the application route
- Prior approval is property-specific: all prior approval classes are dependent on the specific use class, history, and characteristics of the individual building; confirm the current and historical use class of any building before relying on a prior approval route
- Local planning policies still apply at full application stage: prior approval removes general planning policy from the decision on the specified matters; if a full planning application becomes necessary (e.g. because the building exceeds floorspace limits), local planning policies on affordable housing, design standards, and commercial floorspace protection will apply
Frequently asked questions
What is prior approval and how is it different from planning permission?+
Prior approval is a simplified planning procedure under the GPDO 2015 where the LPA's assessment is limited to specified technical matters (transport, contamination, flood risk, noise, natural light). Unlike a full planning application, the LPA cannot consider general planning policy, affordable housing requirements, or loss of commercial floorspace. If the specified matters are acceptable, prior approval must be granted. If the LPA fails to decide within 56 days of a valid application, prior approval is deemed granted.
Can I convert an office to flats without full planning permission?+
Yes, via prior approval under GPDO 2015 Part 3, Class MA. The building must have been in Use Class E (offices, shops, light industrial) for at least 2 years and vacant for at least 3 months before the application. The LPA assesses transport, contamination, flood risk, noise, and natural light. The conversion is limited to 1,500 sq m per application. The LPA cannot refuse on grounds of loss of office space.
What is the 56-day rule for prior approval?+
Once a valid prior approval application is submitted, the LPA has 56 days to grant or refuse prior approval. If the LPA does not make a decision within 56 days, the prior approval is automatically deemed to be granted by default. The developer can then proceed with the conversion. Document and timestamp the valid application date carefully — the 56-day clock only runs from the valid (not the submitted) date.
Can I convert a barn to a house under permitted development?+
Yes, via prior approval under GPDO 2015 Part 3, Class Q. The agricultural building must have been in agricultural use before 20 March 2013. A maximum of 5 dwellings can be created from a single agricultural unit, with a total of 1,000 sq m of residential floorspace. The building must be capable of conversion in its existing structure — wholesale demolition and rebuilding is not permitted. The LPA can consider design and external appearance.
Are there areas where prior approval does not apply?+
Yes. Class MA does not apply in Sites of Special Scientific Interest (SSSIs), safety hazard areas, military explosives storage areas, or where the LPA has made an Article 4 Direction removing Class MA permitted development rights (common in central London and other major commercial districts). Class Q does not apply to agricultural buildings constructed after 20 March 2013 or where there are specific GPDO exclusions. Always check the LPA's Article 4 Direction register before relying on a prior approval route.