Commercial to Residential Conversions: Prior Approval Guide

How to convert offices, shops and other commercial buildings to residential use through prior approval, including Class MA and other permitted development routes.

Converting commercial buildings into homes has become one of the most popular development routes in England, thanks to permitted development rights that allow many conversions to proceed through a streamlined prior approval process rather than full planning permission. This guide explains the main routes, conditions, and practical considerations.

What Is Prior Approval?

Prior approval is a lighter-touch application process. Instead of full planning permission, the developer submits a prior approval application covering specific issues (transport, flooding, contamination, etc.). The council can only consider these specified matters - they cannot refuse on wider grounds such as the principle of residential use or the impact on the streetscape.

This makes prior approval significantly faster and more certain than a full planning application.

Class MA - Commercial, Business and Service to Residential

Class MA of the General Permitted Development Order is the most commonly used route. It allows the change of use of buildings in Use Class E (shops, restaurants, offices, light industrial, gyms, health centres, creches, and more) to residential use (Class C3).

Key Conditions

• The building must have been in commercial use for at least 2 continuous years before the date of application
• The building must have been vacant for at least 3 continuous months immediately before the date of application
• Maximum floor space: 1,500 square metres per building
• The building must not be a listed building or a scheduled monument
• The building must not be in a Safety Hazard Zone or Military Explosives Storage Area
• The site must not be an SSSI (Site of Special Scientific Interest)

Prior Approval Matters

The council can only consider the following issues when deciding a Class MA application:

• Transport and highways - impact on the road network
• Contamination - risk from previous commercial use
• Flooding - risk to future residents (check the flood risk map)
• Noise - from commercial premises
• Natural light - adequate daylight to habitable rooms
• Fire safety - adequate means of escape and firefighting access
• Impact on the sustainability of a key shopping area - if the building is in a designated area
• Impact on the intended occupiers from the introduction of residential use in the area

Application Fee and Timeline

The prior approval fee is £125 per dwelling (up to 50 dwellings). The council has 56 days to determine the application - if they do not respond within this period, prior approval is deemed to have been granted.

Class G - Retail (A1/A2) to Residential (Historic Route)

Before Class MA was introduced in August 2021, Class G allowed the change of use from retail (A1 or A2) to residential. This route still technically exists but has been largely superseded by Class MA, which is broader and covers all Class E uses.

The key difference is that Class G was limited to 150 square metres of floor space, whereas Class MA allows up to 1,500 square metres.

Class O - Offices to Residential (Historic Route)

Class O previously allowed office (B1a) to residential conversions. Like Class G, this has been superseded by Class MA for new applications, as offices now fall within Use Class E.

What About Listed Buildings and Conservation Areas?

Class MA prior approval is available in conservation areas - the designation does not prevent the conversion. However:

• Listed buildings are excluded - you cannot use Class MA for a listed building. You will need full planning permission and listed building consent
• External alterations in conservation areas may still require planning permission, even if the change of use is permitted
• Article 4 Directions - some councils have removed Class MA rights in specific areas (typically town centres) through Article 4 Directions. Check with your local council

Practical Considerations

Building Regulations

Prior approval covers only the change of use. The physical conversion work must comply with building regulations, which cover structural safety, fire safety, sound insulation (between flats), ventilation, drainage, and energy efficiency. Building regulations approval is separate and must be obtained before works commence.

Minimum Space Standards

Since 2021, dwellings created through permitted development must meet the Nationally Described Space Standard. This means minimum floor areas of:

• 37 square metres for a 1-bed, 1-person flat
• 50 square metres for a 1-bed, 2-person flat
• 61 square metres for a 2-bed, 3-person flat
• 70 square metres for a 2-bed, 4-person flat

Natural Light

One of the most contentious issues in office-to-residential conversions is natural light. Many office buildings have deep floor plates with limited window openings, making it difficult to provide adequate daylight to all rooms. This is now explicitly assessed as part of the prior approval process, and proposals with inadequate natural light can be refused.

Affordable Housing

Developers using Class MA must pay a Community Infrastructure Levy (CIL) where applicable. However, unlike full planning permission, prior approval does not allow councils to require affordable housing through Section 106 agreements. This is one reason why the PD route is commercially attractive to developers - but also why some councils oppose it.

Council Tax and Business Rates

Once converted, the building will switch from business rates to council tax. This happens when the conversion is complete and the properties are habitable.

When Full Planning Permission Is Better

While prior approval is faster and more certain, there are situations where a full planning application may be preferable:

• Floor space exceeds 1,500m² - Class MA does not apply
• Significant external alterations are needed - demolition and rebuild, new floors, extensions
• Listed buildings - prior approval is not available
• Mixed-use proposals - retaining some commercial space at ground floor level
• The building has not been vacant for 3 months - the vacancy requirement may not be met

Steps to Converting a Commercial Building

1. Confirm eligibility - check the use class, floor area, vacancy period, and any Article 4 restrictions
2. Commission a feasibility study - assess the building's suitability for residential conversion (layout, light, structure, services)
3. Submit prior approval application - include floor plans, flood risk assessment, transport statement, contamination report, and noise assessment as applicable
4. Obtain building regulations approval - separate application for the physical conversion works
5. Complete the conversion - typically 3 to 12 months depending on scale
6. Notify the council - confirm completion for council tax purposes

Commercial to residential conversions represent a significant opportunity for developers and investors. With the right building and a clean prior approval application, the route from empty shop or office to occupied flats can be remarkably fast. Check your local council's position on Article 4 Directions and use Planning Signal to research what conversions have been approved in your target area.