Commercial and interiors architects

Commercial and interiors work covers new non-domestic buildings and changes inside or to existing ones: offices, shops, cafés, clinics, gyms and studios. A fit-out turns an empty shell or tired unit into usable space, and a change of use changes what the building is legally for. Both usually need design, drawings and consents, and both carry duties that fall on the client as well as the designer.

What is Class E, and do you need planning permission to change use?

Class E is the planning use class for commercial, business and service uses. Under Schedule 2 of the Use Classes Order it covers shops, food and drink consumed mostly on the premises, financial and professional services, indoor sport and fitness, medical services, creches and day nurseries, offices, research and development, and industrial processes that can be carried out in a residential area without harming its amenity (legislation.gov.uk). It was inserted on 1 September 2020.

In most cases moving between uses within Class E needs no planning application. The Planning Portal's example is a shop becoming a café: the change stays within Class E, so permission is not normally needed, but a commercial extractor flue needs permission, new signs are likely to need advertisement consent, and tables on the pavement will very likely need a licence from the highway authority (Planning Portal).

Listed buildings, conservation areas and planning conditions on an earlier consent can all override these general rules. Our planning applications page covers how applications work when permission is needed.

Do Building Regulations apply when the use changes?

Yes, they can apply even where planning does not. Building Regulations have their own idea of a material change of use. Regulation 5 lists the cases, including a building becoming a shop, a hotel or boarding house, an institution or a public building when it was not one before (legislation.gov.uk). A shop moving to a café may therefore be a planning non-event but still raise building control questions, so check which test applies.

When regulation 6 applies, the building has to meet listed requirements. These include fire safety, ventilation and energy efficiency in every case, with access and facilities (Part M) added for some changes, such as a building becoming a shop, hotel, institution or public building (legislation.gov.uk). That is why a fit-out budget should carry a line for upgrading escape routes, ventilation and toilets.

What does Part M mean for an accessible fit-out?

Part M covers access to and use of buildings. For non-domestic buildings the guidance is Approved Document M, Volume 2, and GOV.UK lists the edition incorporating the 2024 amendments, updated on 1 October 2024 (GOV.UK). In practice it shapes step-free entrances, door widths, lifts, accessible toilets, counters and signage. Design them in at the layout stage, because a late fix often moves walls.

How does fire safety law work alongside the Building Regulations?

They overlap but are different. Building Regulations deal with the design and construction of the building. The Regulatory Reform (Fire Safety) Order 2005 puts an ongoing duty on the responsible person, usually the employer or whoever controls the premises, to carry out a fire risk assessment and keep it under review (GOV.UK). The Order requires a suitable and sufficient assessment and a written record (legislation.gov.uk).

For a fit-out this matters twice. The design must provide proper means of escape, and the tenant or operator must keep the risk assessment current once they move in. Changing the layout, adding mezzanines or partitioning a floor usually means revisiting the assessment. The Order applies in England and Wales; Scotland and Northern Ireland have their own rules.

Who is the principal designer under the 2023 dutyholder rules?

Part 2A of the Building Regulations 2010, inserted by regulations that came into force on 1 October 2023, sets duties for clients, designers, contractors and the two lead roles of principal designer and principal contractor (legislation.gov.uk). Where there is more than one contractor, or more than one is foreseeable, the client must appoint both in writing (legislation.gov.uk).

Which energy rules apply to non-domestic work?

Approved Document L Volume 2 covers buildings other than dwellings. The edition incorporating 2023 amendments is the current guidance, and the 2026 regulations come into force on 24 March 2027, with transitional protection where a notice or full plans were given beforehand and work starts within a year of that date (GOV.UK). Ask building control which edition applies to a project that straddles that date. Our renovation and retrofit page explains the comparable rules for homes.

What should you ask before hiring an architect for a commercial fit-out?

• Which similar premises have you taken from brief to completion, and can I speak to a past client?
• Will you check the use class and any planning conditions before we sign a lease?
• Who will act as principal designer, and how do you show competence?
• How will fire escape, accessibility and ventilation be tested at layout stage?
• What does the fee include, such as tender, site visits and building control, and what is extra?
• What professional indemnity insurance do you hold, and for what limit?

Take written quotes on one shared brief, and agree what you will get at each stage. Do not rely on any figure you cannot trace to a quote.

How do you check a commercial architect is on the ARB register?

1. Open the Architects Register, maintained by the Architects Registration Board.
2. Search the name of the person or practice on your quote.
3. Confirm the entry is current, and that the name matches the contract.
4. Use only registered people as the architect: the ARB says that if someone is not on the Register, they are not an architect.

Starting a project at home instead? Look at extensions, or browse guides and cities to find a practice near you.