For office tenants and landlords
Cat A vs Cat A+ vs Cat B Fit Out: Understanding the Key Differences
Sviatoslav JerdetchiiCEO & Founder of Craftex. Updated , 6 min read
The short answer
Cat A is the landlord's empty, serviced floor; Cat B is the tenant's fit-out on top, with rooms, kitchen, furniture and IT. Cat A+ sits between: a Cat A floor the landlord has furnished.
- Cat A has raised floors, ceilings, lighting, air conditioning and a fire alarm, but no rooms.
- Cat A+ adds desks, a few meeting rooms, a kitchen and data, ready to move in.
- Cat B is your own layout, finishes, furniture, AV and brand.
- The landlord usually pays for Cat A; the tenant usually pays for Cat B.
"Cat A" sounds like a finished office. It isn't. It is an empty floor with the services in, and nothing you can work at.
The difference between Cat A, Cat A+ and Cat B decides three things. What you get on day one, who pays for it and what you put back when you leave.
This guide compares them item by item, from the contractor's side. If you are looking at a floor now, book a site visit and we'll tell you what it really includes.
Cat A vs Cat B fit-out: the short difference
Cat A is the landlord's base fit-out. The floor has services and finishes, but it is open and empty.
Cat B is the tenant's fit-out on top of Cat A. It turns the empty floor into your office: rooms, kitchen, furniture, IT and brand.
Cat A+ is a Cat A floor that the landlord has also furnished. It is sometimes called "plug and play".
There are no official definitions. These are market terms, and landlords use them slightly differently. Always read the specification, not the label. For where shell and core fits in, see our overview of the four types of office fit-out.
What a Cat A fit-out includes
A Cat A floor is usable but not furnished. It usually includes:
- Raised access floors for power and data
- Suspended ceilings
- Lighting on a regular grid
- Air conditioning and ventilation
- A fire alarm and emergency lighting
- Toilets and basic finishes
It usually leaves out every room, the kitchen, the furniture, the IT and anything with your name on it. A Cat A specification document lists exactly what the landlord installs. Ask for it before you sign.
What a Cat A+ fit-out adds
Cat A+ starts with the Cat A floor and adds what a small team needs to move in. That usually means desks and chairs, a few meeting rooms, a kitchen or tea point and data cabling.
It suits shorter leases and teams that need to move quickly. The trade-off is control. The layout, finishes and furniture are the landlord's choice, and changing them later is your cost.
I had an amazing experience working with Sviat and the Craftex team on our office fit-out in London. They were always professional, responsive, and quick to offer the best advice whenever decisions needed to be made. I really appreciated how they balanced style with practicality — the office doesn’t just look fantastic, it works perfectly for our team. Everything was done with care and attention to detail, and the project never felt overwhelming because they managed it so well. Communication was clear from start to finish, and I always felt involved in the process. I would happily recommend Craftex to anyone looking for a trustworthy contractor.
What a Cat B fit-out includes
Cat B is built around the way your team works. It usually covers:
- Partitions, meeting rooms and focus rooms
- Kitchen, breakout and reception
- Floor, wall and ceiling finishes, joinery and branding
- Furniture and storage
- IT, AV, access control and security
- Changes to the Cat A lighting, air conditioning and fire alarm to suit the rooms
Cat B is also where accessibility is designed in, from door widths to quiet rooms. Our article on inclusive office design explains why that matters in London.
Cat A vs Cat A+ vs Cat B, item by item
This is how the three usually compare. Check each line against your landlord's specification.
| Item | Cat A | Cat A+ | Cat B |
|---|---|---|---|
| Raised floor and ceilings | Yes | Yes | Kept or changed |
| Lighting and air conditioning | Grid for an open floor | Grid for an open floor | Adapted to your rooms |
| Fire alarm | Open-floor layout | Open-floor layout | Adapted to your rooms |
| Partitions and meeting rooms | No | A few, standard | Your layout |
| Kitchen or tea point | No | Basic | Designed for you |
| Furniture | No | Standard | Chosen for your team |
| IT, data and AV | Containment only | Data cabling | Full IT, AV and security |
| Branding and finishes | Neutral | Neutral | Your brand |
| Usually paid by | Landlord | Landlord | Tenant |
| Ready to work in? | No | Almost at once | Yes, once built |
Who pays for Cat A and Cat B
The landlord usually pays for Cat A and the tenant for Cat B. With Cat A+, the landlord pays for the furniture and rooms up front.
On a new letting there is often room to negotiate. If you will rip out part of the Cat A anyway, ask for a contribution to your Cat B instead. Our guide to landlord fit-out contributions explains how to ask.
Landlords must also meet energy rules. Since 1 April 2023, a non-domestic property can only be let with at least an EPC E rating, unless exempt. Ask for the floor's EPC early.
Where Cat A and Cat B clash
A Cat A floor is designed for one big open room. Every wall you add changes it.
- Lighting. Lights on a grid may land on top of a new partition. Some move, some are added.
- Air conditioning. Enclosed rooms need their own air supply and often their own control.
- Fire alarm. Detectors and sounders must cover every enclosed room.
- Floor boxes. Power and data points move to where the desks actually go.
- Ceilings. Partitions to the soffit mean cutting the new ceiling.
This is why your layout decides your Cat B cost. Our guide to the main types of office layout shows what each layout means for the build.
What Cat B costs on a Cat A floor
At our 2026 London rates, a Cat B fit-out on a Cat A floor costs about £88 per sq ft at basic spec. Mid-range is about £128 and high spec £183+, excluding VAT.
That includes construction, furniture and AV. Cat A works are priced separately, because they depend on the building's existing services. Our office fit-out cost guide has budgets by office size and the costs people forget.
Approvals and the end of the lease
Internal alterations usually don't need planning permission. A listed building needs listed building consent for significant works. Most Cat B fit-outs still need building regulations sign-off for fire safety, ventilation and electrics.
Most leases also need the landlord's licence for alterations before work starts. Read the reinstatement clause too. Some leases ask the tenant to strip the Cat B and return the floor to Cat A at the end. That is a cost to plan for.
Two Craftex projects: Cat B only, and Cat A plus Cat B
Beaumont House: a Cat B fit-out on an existing floor
Beaumont House in High Street Kensington was a run-down 750 sq m office. The services were there, so the work was the tenant layer. We demolished walls for an open-plan floor and built frosted glass meeting rooms.
Lighting and wiring were replaced, data runs under the floor to every desk, and there is a new kitchen, CCTV and access control. The client had five weeks left on their lease. We handed over in three weeks for £350K.
Portsoken House: both stages in one programme
Portsoken House in Aldgate was an abandoned warehouse. It needed the base works and the fit-out together.
| Stage | Work we carried out |
|---|---|
| Cat A level | Full mechanical and electrical package, new ceiling, concrete floors levelled |
| Cat B level | New entrance, kitchen and WCs, office layout and finishes |
Doing both stages together meant nothing was installed twice. The rest of the building stayed let throughout.
Which fit-out suits your business
Start with the lease and the team, not the finishes.
| Your situation | Usually the best fit |
|---|---|
| Short lease, small team, need to move fast | Cat A+ |
| Long lease, team with specific rooms and workflows | Cat B on Cat A |
| Signing early, before the landlord's Cat A is built | Cat B, with a landlord contribution instead of Cat A |
| Landlord letting a vacant floor to small occupiers | Cat A+ |
| Landlord letting to an unknown tenant | Cat A |
The design factors behind a good Cat B are in our guide to workspace design factors. For ideas on the look, see our office design trends.
One team from Cat A to Cat B
Most delays happen between parties: the landlord's surveyor, the designer, the engineer and the builder. Our office fit-out service puts design and construction under one contract. Our office design and space planning team fixes the layout before anything is built.
Fitting out shops, clinics or other premises? See commercial fit-out and refurbishment. Moving offices? Our office relocation checklist covers the rest of the move.
We take on office fit-outs from £100,000 to £10M+. If you are comparing floors or about to sign, book a site visit. We'll check what the landlord hands over and what your team needs on top.
