What Is a Commercial Fit Out?
In short
A commercial fit out is the process of making an internal space ready for a business to occupy, such as an office, shop, clinic or restaurant. It covers partitions, ceilings, floors, lighting, mechanical and electrical services, finishes and furniture, and is usually described as Category A or Category B.
A commercial fit out takes a building or unit and makes it ready for a business to move in and work. The starting point varies, from a bare concrete shell to a previous tenant’s space that needs stripping out, but the aim is the same: a workplace that functions well, reflects the brand and meets every regulation, delivered on a fixed date so the business can open.
The stages of a building’s interior
- Shell and core: the landlord provides the structure, building envelope, common parts, lifts and main services, but the tenant’s floor is bare.
- Category A: a basic, usable space with raised floors, suspended ceilings, lighting, heating and cooling, and toilets. See Cat A vs Cat B fit outs.
- Category B: the tenant’s own fit out: meeting rooms, kitchens, reception, branding, data, furniture and the finishes that make it theirs.
- Turnkey: one contractor delivers everything, ready to use on day one.
What a fit out includes
- Strip out of the previous occupant’s fit out
- Partitions, glazed screens, doors and acoustic treatment
- Ceilings, flooring and wall finishes
- Mechanical and electrical services: heating, cooling, ventilation, power, lighting, data and security
- Kitchens, tea points, toilets and showers
- Fire alarms, emergency lighting, fire stopping and means of escape
- Joinery, signage, furniture and branding
Approvals to plan for
- Landlord consent, usually a licence for alterations, with the landlord’s surveyor reviewing the design.
- Building regulations for fire safety, accessibility, ventilation and energy.
- Planning permission where there is a change of use or external alteration.
- Health and safety duties under the Construction (Design and Management) Regulations 2015, which place responsibilities on commercial clients.
Keeping a fit out on programme
Lease dates and opening dates are fixed, so programme is everything. Long lead items such as air conditioning plant, glazed partitions and bespoke joinery should be ordered early. Many fit outs happen in occupied buildings, so working hours, noise, deliveries and access need careful planning with the building manager. Our article on refurbishing offices without disrupting business covers this in more detail.
Design and brand
A good fit out does more than meet the brief. Light, acoustics, storage and the arrival experience all shape how staff work and how clients see the business. Good quality materials and careful detailing at reception, meeting rooms and washrooms make the biggest impression for the budget.
Think about the exit at the start
Most leases require tenants to reinstate the space when they leave. Recording what you install, and agreeing reinstatement terms early, reduces dilapidations costs at the end of the lease.
How we handle commercial fit outs at London’s Prestige
We deliver fit outs as one managed project: landlord liaison, approvals, programme, trades and handover, with one point of contact and regular progress reports. We bring the same craftsmanship to offices, clinics and retail spaces that we bring to London homes. Find out more about our commercial refurbishment service, and book a site visit to discuss your space and opening date.
Common questions
How long does a commercial fit out take?
It depends on size and scope. A small office or retail unit can take a few weeks; larger Category B fit outs take several months. Long lead items and landlord approvals often set the timeline.
Do I need landlord permission for a fit out?
Almost always. Most commercial leases require a licence for alterations, and the landlord's surveyor will review the design before work starts.
What is the difference between a fit out and a refurbishment?
A fit out prepares a space for a specific occupier. A refurbishment improves or renews an existing space. In practice, many projects include elements of both.