If you are taking on new office space, you will hear agents and landlords talk about Cat A and Cat B. The terms describe how far a space has been fitted out, and they decide what you pay for, what the landlord pays for, and how long it takes before your team can move in.
Here is what each stage includes, in the order a building goes through them.
Shell and core
Before any fit-out, an office floor is shell and core. The structure, roof and outside walls are finished. So are the shared parts of the building: entrance, stairs, lifts, toilets in the core and the main heating, cooling and electrical plant.
The floor itself is bare. There are no ceilings, no raised floor and no lighting. Nobody can work in it yet.
Cat A: ready to let
A Cat A fit-out turns shell and core into a clean, open floor that a landlord can let. It is usually the landlord's cost. A typical Cat A includes:
- raised access floors, for power and data cabling
- suspended ceilings
- general lighting across the floor
- heating, cooling and ventilation distributed to the space
- fire detection and alarms
- finished walls and toilets, if they are not already in the core
The result is a blank, open-plan floor. It meets building regulations and is ready for a tenant, but it has no meeting rooms, no kitchen, no furniture and nothing that says whose office it is.
Cat B: ready to work in
A Cat B fit-out turns that blank floor into your workplace. It is designed around how your business works and is usually the tenant's cost. It can include:
- partitions, meeting rooms, offices and phone booths
- reception and front-of-house areas
- tea points, kitchens and breakout spaces
- desks, seating and storage
- power and data to desks, plus audio-visual equipment
- lighting and air conditioning adjusted to suit the new layout
- joinery such as reception desks, boardroom tables, wall panelling and storage walls
- flooring, finishes, signage and branding
This is the stage where the space starts to feel like your business.
Cat A+: let ready to move in
Some landlords now offer Cat A+, sometimes called plug and play. The landlord carries out the Cat A works and adds some of what would normally be Cat B: a few meeting rooms, a kitchen, furniture and data. A tenant can move in within days of signing.
Cat A+ suits smaller businesses and short leases. The trade-off is that the layout and finishes are chosen for a typical tenant, not for you.
Who pays for what
As a rule, the landlord pays for Cat A and the tenant pays for Cat B. In practice it is often negotiated. A landlord may offer a contribution towards the Cat B works, or a rent-free period, to help you take the space.
It is worth asking whether you can take the floor before Cat A is finished. New Cat A ceilings and lighting are often taken out again when the Cat B layout goes in. If you agree the layout early, the landlord can skip those parts and put the saving towards your fit-out. It saves money, time and waste.
What to check before you sign
- What is in the Cat A. Ask for the specification, not just the term. Two buildings described as Cat A can be quite different.
- The condition of the services. Older heating, cooling and electrics can limit what your layout can do, or add cost.
- Landlord's consent. Most leases need the landlord's approval for alterations. Allow time for it in your programme.
- Reinstatement. Find out whether you must strip out your Cat B works at the end of the lease. It affects what you build and how.
How we help
We carry out both. For landlords and agents, we deliver Cat A refurbishments that make space ready to let. For occupiers, we design and fit Cat B workplaces, and make the joinery in our own workshop in Downpatrick, so reception desks, boardroom tables and storage are built to fit the space exactly.
If you are looking at a space now, we can visit it with you and tell you what it will take to make it work. There's no charge for a first conversation.
Uno Interiors, Downpatrick. Published 29 October 2026.
