Class MA floorspace limits and the conversion threshold

The Class MA floorspace limit no longer exists. From 1 August 2021, when the right to convert commercial, business and service premises to dwellings was introduced, Class MA of Part 3 of Schedule 2 to the General Permitted Development Order carried a cap of 1,500 m² and a requirement that the building had been vacant for three months. A 2024 amendment removed both. Anyone working from guidance written before March 2024, and a good deal of it is still online, will apply limits that have gone.

What remains is the continuous use requirement, the prior approval matters, and a long list of exclusions. Those are what decide whether a scheme works.

The scope of the right and what it covers

Class MA permits change of use from Class E, the commercial, business and service use class, to Class C3 dwellinghouses. Class E is broad: shops, restaurants and cafes, offices, light industrial, gyms, nurseries, clinics and indoor sport all sit within it.

The right covers change of use. Building operations reasonably necessary to convert are permitted in a limited way, though anything substantial, including external alterations of any consequence, needs a separate planning permission. Do not assume you can add windows, alter the roof or build out.

A number of situations are excluded entirely. Listed buildings and land within their curtilage, scheduled monuments, sites of special scientific interest and certain safeguarded areas are outside the class, and additional considerations apply in conservation areas. The full list sits in the class itself and it is amended periodically, so read the current consolidated text rather than a summary.

The floorspace position and how it changed

The removal of the cap changed what the right is for. A 1,500 m² limit made Class MA a small-building tool suited to a high street unit or a single office floor. Without it, whole office buildings fall within the class, subject to the prior approval matters.

That has consequences beyond the planning route. A large conversion still needs to satisfy Building Regulations, fire safety requirements and, for higher-risk buildings, the gateway regime, none of which the permitted development right touches.

Verify the current position before advising. Permitted development rights are amended frequently, and this class has already been changed twice.

The continuous use requirement

The building must have been in a use falling within Class E for a continuous period of at least two years before the date of the prior approval application. This is the requirement that most often defeats an application.

Evidence it properly. Useful material includes business rates records, leases and licences covering the whole period, utility accounts, dated photographs, company accounts showing trading at the address, and statutory declarations from the occupier or the owner. A single lease covering two years is good evidence. A lease with a six-month gap in the middle is a problem, because the use has to have been continuous.

Mixed buildings need care. Where part of a building was in Class E use and part was not, the two-year test applies to the part being converted, and the evidence has to distinguish between them.

Prior approval matters the authority considers

The authority cannot refuse on general planning grounds. It can only consider the matters listed in the class, which include transport impacts particularly on highway safety, contamination risk, flood risk, noise from commercial premises affecting future occupiers, the impact of losing the ground floor use in a conservation area, the effect of introducing residential use into an area important for industry or storage, and the provision of adequate natural light in all habitable rooms.

Each of those is an evidence question rather than a policy argument.

• Contamination usually needs a desk study, and a former light industrial or vehicle-related use will attract a request for a contaminated land assessment.
• Noise affecting future occupiers is assessed against the surrounding commercial uses, and a building next to a late-licensed venue or a servicing yard will need a Noise Impact Assessment with a glazing and ventilation strategy.
• Natural light is the one that catches deep-plan office floors. Habitable rooms need adequate natural light, and an internal bedroom will fail. Where the layout is marginal, a Daylight and Sunlight Assessment of the proposed internal conditions is worth submitting rather than waiting for the question.

There is also a condition requiring the new dwellings to meet the nationally described space standard, which on an awkward floorplate is often the binding constraint on unit numbers.

Article 4 directions removing the right

A local planning authority can remove Class MA in a defined area by making an Article 4 direction, and a number have done so for town centres and office locations they want to protect.

Check the direction's exact boundary and its date. Directions are made for specified areas and sometimes for specified uses within the class, so a direction covering the primary shopping frontage may not cover the street behind it.

Where a direction applies, the route is a full planning application assessed against the development plan, and the loss of employment or retail floorspace then becomes a policy issue with a very different outcome.

Where a full application is the better route

Class MA is not always the right choice even where it is available. A full application allows external alterations, extensions, a different unit mix and a scheme that is not constrained by the prior approval matters or by the space standard condition.

Three situations favour the full application route. Where external works are substantial. Where the two-year use evidence is weak or contested. Where the conversion only works with additional floorspace. Against that, a full application engages the whole development plan, including affordable housing policy on larger schemes, and takes longer. The small site thresholds that trigger those policies are worth checking, as set out in the permission in principle small site limit.

Evidence to assemble before applying

Gather six things before submitting: proof of continuous Class E use for two years, a plan showing the extent of the building being converted, existing and proposed floor plans with room areas against the space standard, a daylight position for every habitable room, a contamination desk study, and an acoustic assessment where commercial neighbours exist.

The prior approval period is short, so an application that arrives without this material invites a refusal rather than a request. Authorities are not obliged to chase, and on a prior approval they rarely do.

And check the current text of Class MA on the day you apply. The class has been amended twice already, and a summary written last year may no longer be accurate.

Enter your postcode on PlanScope to see which reports a commercial to residential conversion is likely to need.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. A Lawful Development Certificate is the only formal way to confirm that works are lawful. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.