2024 is the year to convert commercial buildings into residential use

Matthew Robinson, senior architect, argues there’s never been a better time to convert commercial buildings to residential use because of changes to Class MA residential development rights. Here, Matthew talks us through his thinking and the challenges that will inevitably present themselves. 

In August 2021, the General Permitted Development Order introduced Class MA conversion rights. This enabled commercial buildings (Use Class E) to be converted to residential use (Class C3) via permitted development (PD). Further amendments to this order published in February 2024 (and actioned from 5th March) removed any previous restriction on the size of buildings to be converted as well as the three-year vacancy requirement. This legislative change has, therefore, created new opportunities for the conversion of larger commercial buildings, as well as those still in use.

The amendment came about following changes to the NPPF in late 2023, which put greater emphasis on utilising brownfield development and increasing density in urban areas. Class MA conversions offer a tangible strategy in achieving this goal.

On paper commercial to residential conversions present a favourable option for developers, as they are generally quicker to deliver and are therefore a more cost-efficient option. When designed well, conversions can offer a meaningful contribution to the housing shortfall as commercial areas are usually well connected to public transport and within walking distance of local amenities. Having an existing building skeleton to convert rather than building new also reduces associated embodied carbon, therefore often making conversion the more sustainable option.

What are the hurdles faced in practice?

In terms of planning legislation, the amended Class MA rights still do not apply to listed buildings or those subject to Article 4 Direction, within a site of scientific interest, outstanding natural beauty or agricultural tenancy, which does somewhat limit viability.

For opportunities that do fall within Class MA rights, the main challenges of conversion relate to design: notably, access to natural light and ventilation; ability to make improvements to the existing building fabric regarding thermal and sound performance; provision of external amenity space, and lack of privacy and security. This is all because commercial buildings are of course not designed for residential use, and the suitability of commercial buildings for conversion varies drastically. Any external changes to an existing building needed to address these challenges are usually outside of PD rights and are therefore subject to further planning applications. Developers will then find themselves at the mercy of local authorities. Just because the planning route is more direct, the path to a completed residential conversion may well be more complex than how it looks on paper.

In summary, these are the main considerations of conversion from an architectural perspective:

• Ensure there is adequate access to natural light. Dark and isolated homes are not well regarded by planning authorities or the housing market, so it is therefore imperative to provide adequate levels of natural light for every home created. The existing availability of daylight can be improved by installation of rooflights or new windows, however any external changes to an existing building are subject to an additional planning application. 
• The quality of the existing building fabric, in terms of thermal and sound performance, must be considered. Thermal insulation, either by retrofit or upgrading the existing fabric, is almost always required to meet current building regulations. Single pane windows and single skin buildings will usually require more work to meet current performance thresholds, although some older buildings with 9” (215mm) thick brick walls make good conversions if they are of good build quality. 
• Sound insulation is also difficult to improve without significant alterations to an existing building. Replacing windows, for instance, will be subject to a further planning application and will likely be required to meet current building regulations and provide a comfortable space for living. An alternative can be secondary glazing; however, the cost and user convenience must be considered.
• Windows of commercial buildings are likely to be the sole means of ventilation in a PD conversion. If it is impractical to keep windows open, for instance if the building is public facing with no or little separation from public realm, there may be little or no ventilation. If this is the case, it may be best to submit an additional planning application to enable increased ventilation, either passively through more windows or through (additional) mechanical systems. 
• Security and privacy are big considerations. Most commercial buildings will be located in well trafficked public areas which do not naturally make secure homes. Living in a converted ground floor flat on a busy high street, for instance, is only going to appeal to some residents as there is a perceived greater risk to safety and wellbeing. Defensive measures such as landscaping or providing a perimeter wall around the property can provide security and defensible space. Though, these measures will also be subject to additional planning applications. 
• Landscaping can provide external amenity space, which is not easily found with existing commercial buildings. Most if not all local authorities will want homes to be provided with private and communal amenity space through the provision of balconies, patios, gardens and open landscaped spaces.
• PD conversions are now subject to national space standards (March 2015). When converting existing buildings this requirement may lead to peculiarly shaped rooms, due to the nature and build quality of older buildings or the existing structural elements. 

What’s the solution?

These challenges can be avoided by intelligently sourcing existing buildings that are best suited for conversion. Buildings that were once residential are obviously best suited to being converted back, because they will have more domestic proportions with smaller, more frequent windows, and are usually set back from the public realm, offering better security and potential for external amenity space.

As noted, a shortfall in any area of consideration can be compensated by submission of further planning applications. This can create a more valuable end product and help achieve greater opportunities for natural light, ventilation, amenity space and security, helping to address the considerations that potential residents will be looking for.

If there are too many constraints, such as contamination or a poor existing structure, then it may well be better to demolish and rebuild.

In summary, the amended class MA PD rights will provide more brownfield development and more opportunities for housing within urban centres. There are, however, several considerations that will determine whether a building is suitable for conversion as outlined above, which will need to be assessed on a case-by-case basis.

Engagement with architects and planning consultants from an early viability stage can enable developers to select the most suitable buildings for conversion, and help avoid unforeseen challenges. This collaboration will determine the success of the Class MA amendments in achieving its aim: to provide more good quality housing in sustainable and deliverable locations.

Images: Daniel McCullough and Sunrise

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