Class MA prior approval or full permission for flats

Class MA prior approval is faster and narrower than a full application, and it costs less, and it is the right route for an office to flats conversion only when the building passes every eligibility gate and the scheme needs no change to the external envelope. A full application under section 70 of the Town and Country Planning Act 1990 costs more and takes longer, but it lets you alter the building, add floorspace, argue the planning merits and secure a permission that is not vulnerable to an argument about whether a limitation was met.

The deciding question is rarely which route is quicker. It is whether the conversion you actually want fits inside what Class MA permits.

What Class MA does

Class MA sits in Schedule 2 Part 3 of the General Permitted Development Order 2015 and permits a change of use from Class E, the commercial, business and service class, to Class C3 dwellinghouses. It grants the change of use only. It does not grant external alterations, new windows, extensions, balconies, changes to the roof or new access arrangements, all of which need their own permission.

Before anything else, read the current consolidated text of Class MA. The eligibility gates in it, including how long the building must have been in Class E use, any requirement that it be vacant, and any cap on the floorspace changing use, have been amended since the class was introduced in August 2021. Commentary written against the original version is no longer a safe guide, and these are the provisions on which a prior approval application stands or falls.

Class MA is also unavailable in defined circumstances. A listed building or land within its curtilage is excluded, as is a scheduled monument and its curtilage, a site of special scientific interest, a safety hazard area and a military explosives storage area. Buildings on agricultural land occupied under an agricultural tenancy are excluded, and so, broadly, are buildings whose current use was itself granted by one of the earlier residential conversion classes in Part 3.

What the council can and cannot consider

Prior approval is not a merits assessment. The authority may only consider the matters the Order lists, which for Class MA are:

• Transport and highways impacts of the development.
• Contamination risks in relation to the building.
• Flooding risks in relation to the building.
• Impacts of noise from commercial premises on the intended occupiers.
• Where part of the building is on a ground floor and in a conservation area, the impact of the change of use on the character or sustainability of the conservation area.
• The provision of adequate natural light in all habitable rooms.
• Where the building is in an area the authority considers important for heavy industry, waste management, storage and distribution or a mix of such uses, the impact of the introduction of residential use.
• The design and external appearance of the building, where that is relevant to the matters above.

Everything else is off the table. Affordable housing, policy compliance with the development plan, the loss of employment floorspace as a matter of principle, amenity for neighbours and parking standards are not prior approval matters. That narrowness is the whole attraction of the route.

Natural light is the condition that most often defeats a scheme. Deep plan office floorplates produce internal bedrooms with no window, and a prior approval must be refused where adequate natural light is not provided to all habitable rooms. Draw a plan with every habitable room's glazing shown before you apply.

Space standards apply either way

A common misreading is that permitted development conversions escape minimum unit sizes. They do not. Homes created through prior approval are subject to the nationally described space standard, which sets minimum gross internal areas by number of bedrooms and occupants, along with minimum built-in storage and a minimum floor-to-ceiling height.

Where a local plan sets different minimum sizes, the interaction between the two is not always obvious, and the reasoning is set out in the comparison of the space standard and local minimum unit sizes.

Run the areas before the appointment of an architect, not after. A floorplate that yields fourteen units on a sketch often yields nine once the standard and the daylight requirement are applied together.

Why a full application is sometimes better

Four situations push towards a full application.

The building needs physical change. Any new window opening, roof extension, balcony, external stair or alteration to the elevations falls outside Class MA, so a scheme requiring them needs a planning application anyway. Running two routes in parallel, prior approval for the use and a full application for the alterations, is possible but creates sequencing risk.

The eligibility is arguable. If the building's recent use history, vacancy position or floorspace sits close to a limitation, a prior approval granted on a contested basis is a weak asset. A purchaser's solicitor will ask, and the answer has to be clean.

You want more than the envelope allows. Additional storeys, infill or a change to the footprint need permission, and some of those have their own permitted development routes with their own limitations.

The site is in an area where the authority has used an Article 4 direction to remove Class MA. Several authorities have done so for defined centres and employment areas, and the direction is the first thing to check on the authority's own mapping.

Comparing the two routes

Community Infrastructure Levy liability can arise on either route where the authority has a charging schedule and the floorspace is chargeable, so do not treat prior approval as a levy-free option without checking the schedule and the relevant exemptions.

Evidence for each route

For prior approval, assemble: the application form and fee, a plan showing the building and the floorspace changing use, floor plans showing every habitable room with its glazing, a noise assessment where commercial uses adjoin, a contamination screening note, a flood risk position, a transport note covering access and parking, and documentary evidence of the building's use history. Keep the use history evidence to primary documents, meaning leases, business rates records, accounts and dated photographs.

For a full application, the pack is the normal one and the documents follow from the site's constraints. The index of report types shows which are usually in play for a residential conversion, and the daylight, noise and transport work tends to be deeper because the authority is assessing merits rather than a closed list.

Either way, settle the route before the design is fixed. Switching from prior approval to a full application after a refusal costs a quarter and a fee, and the alternative appeal route differs by application type in the way described in the note on householder and fast track commercial appeals.

Draft the supporting documents for a conversion on PlanScope, then have them reviewed before submission.

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.