Reports needed for an office to residential conversion

The reports needed for an office to residential conversion under Class MA are set by the prior approval matters, not by what the council would like to see. Transport and site access, contamination, flooding, noise reaching the future residents, adequate natural light to habitable rooms, and in some locations the effect on a conservation area or on a designated industrial area. That list is the brief. Anything outside it is not a reason for refusal, and anything inside it left unevidenced is.

Class MA sits in Part 3 of Schedule 2 to the Town and Country Planning (General Permitted Development) (England) Order 2015 and allows Class E floorspace to become dwellinghouses in Class C3. The building must have been in Class E use for at least two years before the application. Other limits, including a floorspace cap and a vacancy requirement, were removed by amendment in March 2024, so any checklist written before then is out of date. Confirm the current wording before you buy.

What prior approval covers, and what it does not

The authority is not deciding whether residential use is appropriate in principle. That judgement has been made for it by the order.

What it can assess is the specified list of matters. In broad terms those are transport and highways impacts with particular attention to safe site access, contamination risks in relation to the building, flooding risks, the impact of noise from commercial premises on the intended occupiers, and the provision of adequate natural light in all habitable rooms. In a conservation area the authority can also consider the effect of losing a ground floor commercial use on the character or sustainability of the area. Where the building sits in an area important for industry, storage or waste management, it can consider the effect of introducing residents there.

Design, unit sizes beyond the space standard, affordable housing, amenity space and daylight to neighbours are all outside the list. So is local plan policy on protecting employment floorspace, which is a common source of confusion when a council writes a refusal that reads like a full application decision.

Article 4 directions are the real risk. Many authorities have withdrawn Class MA across town centres and employment areas. Check the council's Article 4 mapping before anything else, because a direction removes the route entirely.

Noise evidence for a commercial location

Noise is assessed the other way round from a normal application. The question is what the surrounding commercial activity will do to your residents, not what your residents will do to anyone else.

That means identifying the sources: a neighbouring pub with a smoking area, a delivery yard, plant on an adjacent roof, a bus route, a night-time food premises. The survey has to cover the periods when those sources operate, which usually means a full weekday plus a weekend night rather than a daytime spot check.

The assessment then tests internal levels against recognised criteria for bedrooms and living rooms, and considers whether those levels can be achieved with windows closed and, if so, what ventilation strategy replaces opening windows. A scheme that relies on sealed windows plus mechanical ventilation has to demonstrate the overheating consequences as well. Set that out in a Noise Impact Assessment prepared for the prior approval matter rather than a generic report.

The agent of change principle matters here. Bringing residents next to an established venue does not entitle the venue to be shut down later, and a well-drafted assessment says how the mitigation protects both.

Contamination and the desk study expected

The prior approval matter is contamination risk in relation to the building, which in practice means a Phase 1 desk study.

A competent author reviews historical maps, the building's own use history, records held by the council and the Environment Agency, geology and hydrogeology, and produces a preliminary conceptual site model with a risk assessment. Office buildings are not obviously contaminated sites, but the land under them frequently is: former garages, print works, gasworks, railway land and filled ground all show up on historic mapping.

Where the desk study identifies credible pollutant linkages, the authority can require intrusive investigation, and that is where a programme slips. Commission the contaminated land assessment early, before you exchange, rather than after the prior approval application is submitted. Land contamination reports need a suitably qualified and experienced author working to the relevant British Standard, and a licensed or competent professional is expected for the intrusive phases.

Natural light to habitable rooms

This is the matter that kills the most conversions of deep-plan office floorplates, and it is the one applicants most often under-evidence.

The requirement is adequate natural light in all habitable rooms. Bedrooms and living rooms are habitable. Kitchens, bathrooms and circulation are generally not, though a kitchen-living room clearly is. A bedroom served only by a rooflight over a corridor, or by a window into a light well four storeys deep, is the kind of arrangement that fails.

Authorities differ on the evidence they want. Some accept a schedule showing window area against floor area with a plan. Others want a calculated daylight assessment room by room. A Daylight and Sunlight Assessment covering the internal condition is the safer submission on any floorplate deeper than about 12 metres.

Design responses that work are limited and each costs floor area: cutting a light well, setting back the upper floors, reconfiguring units so habitable rooms sit on the perimeter and non-habitable space occupies the core. Test them before you fix the unit count.

Flooding, highways and the rest of the list

Flood risk is assessed against the Environment Agency mapping and the council's strategic flood risk assessment. In Flood Zone 2 or 3 a site-specific flood risk assessment is required, and residential use is more vulnerable than the office use it replaces, which changes the answer even though the building is not changing shape.

Transport is narrower than people expect. The matter is transport and highways impacts, with particular attention to safe site access. A parking objection on its own is not within scope, but a scheme where refuse vehicles cannot serve the building or where residents would step straight into a service yard is.

Where a full application is needed instead

Class MA is not available everywhere, and pushing a marginal case through prior approval wastes 56 days.

The rights do not apply to a listed building or land within its curtilage, or to a scheduled monument. They are unavailable on certain designated and hazard land. And they cover a change of use with only limited associated works, so any external alteration beyond what the order permits needs its own planning permission.

Where the scheme adds storeys, alters the envelope significantly, or where an Article 4 direction applies, a full planning application is the route. That brings the whole development plan into play: affordable housing, amenity space, daylight to neighbours, unit mix and design. It is slower and it is also the only way to get a scheme that does not fit the prior approval box. For mixed buildings where commercial floorspace is retained below, the evidence pattern is different again and is covered in reports for flats above shops.

What you still need after approval

Prior approval is not the end of the consenting work, and budgets that stop there are wrong.

New dwellings created through permitted development must meet the nationally described space standard, which is a condition rather than a prior approval matter. Building Regulations approval is needed for the material change of use, covering fire safety, sound insulation between dwellings, ventilation, energy and access. Where the building is 18 metres or more in height, the higher-risk building regime brings its own gateways and its own regulator.

Then the practical items: a fire strategy from a competent person, a party wall position if you are cutting into shared structure, utility capacity for the new demand, and a waste storage arrangement the council's refuse team will actually collect from.

Enter your postcode on PlanScope to see which documents a conversion is likely to need before you submit.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. For specialist technical reports, qualified professional input may be required.