This article is for general information only. Seek planning and legal advice before proceeding with a conversion project.
Converting commercial property to residential is one of the most established development strategies in UK property. The introduction of Class MA in May 2021 expanded the range of commercial buildings eligible for conversion via prior approval, making it easier to create residential units from offices, shops, and other Class E premises.
The economics can work well. Commercial buildings are often cheaper per square foot than residential, and the prior approval route avoids the cost and uncertainty of a full planning application. But the compliance requirements (building regulations, fire safety, sound insulation) are substantial, and underestimating build costs is the most common cause of project failure.
Class MA: office and commercial to residential
Class MA of the GPDO permits conversion of any building in use class E to residential dwellings (C3) via prior approval.
The conditions are specific: the building must have been in a qualifying Class E use for at least two continuous years before the date of the prior approval application. The building must have been vacant for at least three continuous months immediately before the application. The total floor space being converted must not exceed 1,500 sqm. The property must not be a listed building, in a conservation area (for the Class MA element), in a SSSI, or in a safety hazard zone.
The council assesses transport impacts, contamination risk, flood risk, noise from nearby commercial premises, and whether natural light is adequate. It cannot refuse on design quality grounds. The prior approval fee is £100 per dwelling created.
Class Q: agricultural to residential
Class Q allows conversion of agricultural buildings on established agricultural units to up to five dwellings, with a total combined floor space of no more than 465 sqm. The building must have been in agricultural use on a specific qualifying date, and the works must be "reasonably necessary" for the conversion.
This means you can convert an existing agricultural building but you cannot demolish and rebuild it. The structural shell must be capable of conversion without substantial reconstruction. If the roof is missing or the walls are structurally unsound, Class Q is unlikely to apply.
Prior approval assesses transport, noise, contamination, flooding, and the design or external appearance of the building.
Build costs
Conversion costs vary widely depending on the condition of the commercial building, the specification of the finished units, and the extent of structural work required.
| Conversion type | Build cost per sqm |
|---|---|
| Office to residential (light refurb, structure retained) | £800 to £1,200 |
| Office to residential (full fit-out, new services) | £1,200 to £1,800 |
| Retail to residential (requires M&E, layout changes) | £1,000 to £1,500 |
| Agricultural to residential (Class Q) | £1,200 to £2,000 |
On top of build costs, budget for professional fees (architect, structural engineer, building control, project manager) at 10% to 15% of build cost, plus CIL if applicable in your council area.
Building regulations
A change of use from commercial to residential triggers building regulations requirements regardless of whether planning permission is needed. The main areas:
Fire safety: residential fire escape routes, compartmentation, smoke detection, and emergency lighting must meet Approved Document B. Sound insulation: party walls and floors between dwellings must meet Approved Document E. Ventilation: habitable rooms must meet minimum ventilation rates under Approved Document F. Natural light: each habitable room should have a window area equal to at least 1/20th of the floor area. Energy efficiency: the conversion must meet current energy efficiency standards (Part L), and you must commission an EPC before letting or selling.
The deal appraisal
Before buying a commercial building for conversion, run this calculation:
Gross Development Value (GDV): the total sales value of the completed residential units based on comparable evidence. Total development cost: acquisition price plus stamp duty (commercial rates, not residential surcharge) plus build costs plus professional fees plus finance costs plus contingency (10-15%). Profit: GDV minus total development cost.
Most lenders and experienced developers target a minimum profit margin of 15% to 20% on GDV. Below that, the margins are too thin to absorb cost overruns, market slowdowns, or delays.
Sources
- Class MA, Town and Country Planning (General Permitted Development) (England) Order 2015, legislation.gov.uk. https://www.legislation.gov.uk/uksi/2015/596/schedule/2/part/3/crossheading/class-ma [Accessed 6 May 2026]
- Planning Portal, "Permitted development rights". https://www.planningportal.co.uk/permission/responsibilities/planning-permission/permitted-development-rights [Accessed 6 May 2026]