If you are exploring a commercial fit out for the first time, you will quickly encounter the terms CAT A and CAT B. They describe two distinct stages of the fit out process and knowing which one applies to your project can save you significant time, money, and frustration.
At Shakery Group, we deliver CAT B fit outs across Essex and the wider UK as part of our end-to-end commercial fit out service. This guide explains what each category means, how they relate to one another, and what you actually need to budget and plan for.
The Four Stages of a Commercial Fit Out
Before diving into CAT A and CAT B specifically, it helps to understand where they sit in the broader fit out process. Most commercial buildings progress through these four stages:
| Stage | What it includes | Typically led by |
|---|---|---|
| Shell & Core | Raw construction only. Structural frame, external envelope, core services (lifts, stairs, toilets) but no internal fitout. | Developer pre-letting or speculative build |
| CAT A | Base building made lettable. Raised floors, suspended ceilings, basic M&E, fire detection, neutral finishes. No partitions or furniture. | Landlord hands this to incoming tenant |
| CAT A+ | CAT A plus basic furniture and infrastructure. A plug-and-play space for immediate occupation — popular with serviced offices and flexible workspace providers. | Landlord or co-working operator |
| CAT B | Fully finished, branded, and operational workplace. Partitions, custom lighting, AV, furniture, kitchen, reception — everything the occupier needs. | Tenant or occupier |
Most commercial tenants picking up a new lease will inherit a CAT A space and need to commission a CAT B fit out to make it operational. Understanding this distinction upfront shapes your budget, your timeline, and your brief.
What is a CAT A Fit Out?
A CAT A fit out takes a shell-and-core building and converts it into a lettable, compliant space. It is almost always commissioned and funded by the landlord or developer – not the incoming tenant.
Think of it as the blank canvas stage. The space is functional and meets all building regulations, but it is not yet ready for occupation by a specific business. There are no partitions, no branding, no furniture, and no specialist infrastructure.
What is typically included in a CAT A fit out?
- Raised access floors
- Suspended ceiling grid with basic recessed lighting
- Basic mechanical and electrical (M&E) systems – power, heating, ventilation, and air conditioning
- Fire detection, alarm systems, and sprinklers to building regulation standard
- Finished common areas – entrance lobbies, stairwells, lifts, and shared WCs
- Neutral wall finishes – typically painted plaster or equivalent
- Basic floor coverings such as carpet tiles or screed
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Key point: CAT A is for the landlord, not the tenant A CAT A fit out makes a building attractive to prospective occupiers. It creates a blank, compliant, neutral space. The incoming tenant will almost always need to carry out a CAT B fit out on top of this before the space is usable. |
What is CAT A+? (And Why Does it Matter?)
CAT A+ is a relatively recent addition to the fit out vocabulary, and one that is increasingly relevant in the UK flexible workspace market. It sits between CAT A and CAT B – delivering a space that is immediately occupiable without the need for a full CAT B programme.
CAT A+ spaces include basic furniture (desks, chairs, breakout seating), Wi-Fi infrastructure, refreshment facilities, and simple meeting room provision. They are sometimes described as plug-and-play offices.
CAT A+ is typically commissioned by landlords targeting short-term or flexible lease occupiers, or by co-working operators fitting out a managed workspace. If you are a business looking for a fully branded, bespoke workplace, a standard CAT B fit out is almost always the more appropriate route.
The British Council for Offices (BCO) provides further guidance on workspace standards and fit out specifications in their published guides – a useful reference when scoping any commercial project.
What is a CAT B Fit Out?
A CAT B fit out is the stage that transforms a CAT A space into a fully operational, branded workplace. This is the phase that most businesses mean when they talk about a commercial fit out. It is commissioned by the tenant – not the landlord – and designed entirely around how a specific organisation works.
This is where design intent becomes reality: your brand identity is woven into the physical environment, your team’s working patterns inform the layout, and every element – from the meeting room acoustics to the kitchen specification – is considered as part of a coherent whole.
What is typically included in a CAT B fit out?
- Internal partitioning – offices, meeting rooms, breakout areas, and reception
- Bespoke lighting design including feature and task lighting
- Full IT and data cabling infrastructure, AV systems, and comms
- Branded wall graphics, colour palettes, and material finishes
- Furniture – desks, chairs, storage, soft seating, and collaborative zones
- Kitchen and welfare facilities
- Acoustic treatments – wall panels, ceiling baffles, and acoustic artwork
- Specialist elements such as client suites, board rooms, or labs depending on sector
What is a CAT A Refurbishment?
A CAT A refurbishment applies the same principles as a CAT A fit out, but to an existing occupied or previously let building rather than a new shell. When a tenant vacates a building, the landlord will often refurbish the space back to a CAT A standard – stripping out the previous occupier’s partitions, furniture, and branding, and restoring the space to a neutral, lettable condition.
This is a common requirement in the UK commercial property market, particularly in London and major regional cities where buildings are regularly re-let between tenants. It is distinct from a CAT B fit out in that the goal is to remove customisation, not add it.
If you are a landlord or asset manager looking to refresh a vacated space ready for re-letting, a CAT A refurbishment is likely what you need. Shakery’s team can advise on scope, specification, and phasing.
CAT A Refurbishment typically involves:
- Strip-out of existing partitions, finishes, and fixtures
- Reinstatement of raised floors and suspended ceilings
- M&E systems checked, upgraded, or replaced
- Neutral redecoration throughout
- Common area refresh if required
CAT A Refurbishment is not:
- A full structural overhaul of the building
- A tenant-led improvement programme
- A CAT B customisation project
- A full mechanical and electrical replacement (unless required)
CAT A vs CAT B: Side-by-Side Comparison
| Factor | CAT A | CAT B |
|---|---|---|
| Who commissions it? | The landlord or developer | The tenant / occupier |
| Purpose | Create a lettable, compliant base space | Create a finished, operational workplace |
| Partitioning | Open plan, no internal rooms | Full partitioning, offices, meeting rooms |
| Branding | Neutral, unfinished | Branded, customised throughout |
| Furniture | Not included | Installed and configured |
| IT & cabling | Basic infrastructure only | Full data, AV, and comms install |
| Typical cost | Lower upfront investment | Higher capital investment required |
| Timescale | 6–12 weeks typical | 8–20 weeks depending on size |
| Result | Move-in ready for fit out | Move-in ready for occupation |
Which Do You Actually Need?
The answer depends on where you are in your occupancy journey.
You need a CAT B fit out if:
- You are a tenant taking on a new or vacant CAT A space
- You need a fully branded, operational workplace built to your specification
- Your business is growing and you need a space designed around how your team works
- You are relocating from an existing fit out and need a fresh start
You need a CAT A refurbishment if
- You are a landlord or developer refreshing a vacated space
- The existing fit out is dated or left in poor condition by the outgoing tenant
- You want to reset the space to a neutral standard ready for re-letting
- You are an asset manager looking to maximise a property’s appeal to prospective tenants
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Not sure? Start with a consultation. Shakery Group regularly works with both landlords and tenants at the early stages of a project — before scope or budget is fixed. A short conversation can clarify which type of project you need and what a realistic programme looks like. Call us on 01376 617530 or fill out our contact form |
Why the Right Contractor Makes All the Difference
CAT A and CAT B projects may sit at different ends of the specification scale, but both demand the same level of coordination, technical knowledge, and programme discipline. M&E sequencing, subcontractor management, material lead times, and building regulation compliance all have to be managed concurrently – and a misstep in any one area can cascade through the programme.
Shakery Group brings over 40 years of combined experience across the team. We hold CHAS Elite and SafeContractor accreditations, and we work across a broad range of sectors – from office spaces and laboratories to retail, healthcare, and education. That breadth means we understand sector-specific requirements rather than applying a generic fit out template.
We also offer early-stage involvement as standard. Before a single partition goes up, our team works with clients on feasibility studies, space planning, and 3D renders – so decisions are made on the basis of accurate information, not assumptions.
Read more about our process and why clients choose Shakery Group.
Common Questions About CAT A, CAT B and CAT A+ Fit-Outs
Can a landlord carry out a CAT B fit out?
In some cases, yes. When landlords are competing for high-quality tenants on long leases, they may offer to contribute to or fully fund a CAT B fit out as part of the lease negotiation. This is sometimes structured as a landlord contribution or a rent-free incentive period. However, the CAT B is almost always designed and specified by the tenant to reflect their own requirements – the landlord simply funds it.
Do I need to carry out a CAT A fit out before a CAT B?
Not necessarily. If you are moving into an existing building that already has a CAT A standard in place, you proceed directly to CAT B. If you are taking on a shell-and-core building, a CAT A phase will typically need to happen first – either commissioned by the landlord or (less commonly) by the tenant. It is always worth clarifying the current condition of a space before signing a lease.
What happens to the CAT B fit out when a lease ends?
Most leases include a dilapidations clause that requires the tenant to return the space in its original condition – typically CAT A standard – at the end of the lease. This means the tenant is responsible for stripping out their CAT B fit out, reinstating floors and ceilings, and making good any changes made during their occupation. The extent of this obligation varies by lease, so it is important to understand your dilapidations position before committing to a CAT B specification.
How long does a CAT B fit out take?
Timescales depend on the size and complexity of the project. A straightforward open-plan office of 2,000–3,000 sq ft might be completed in 8 to 10 weeks. A complex multi-floor fit out with specialist facilities, bespoke joinery, and a phased delivery could take 16 to 24 weeks or more. Design sign-off and procurement lead times add further time ahead of works starting on site – which is why early-stage engagement with your contractor is important.
Can a CAT B fit out be phased around a live working environment?
Yes, in many cases. Phased delivery is a standard approach for businesses that cannot vacate their premises entirely, or those taking on additional floors within the same building. Shakery has experience designing and delivering phased programmes that minimise operational disruption while still delivering a coherent, high-quality result. This requires careful programming and close communication between the contractor and the client’s facilities or operations team.
What is a CAT A+ fit out and who is it for?
CAT A+ is a relatively recent classification that sits between a standard CAT A and a full CAT B. It typically includes basic furniture, Wi-Fi infrastructure, and simple welfare facilities – making a space immediately occupiable without a bespoke CAT B programme. It is most commonly used by flexible workspace operators and landlords targeting short-term or serviced office tenants. For businesses requiring a branded, purpose-built workplace, a full CAT B is almost always the better option.
Talk to Shakery Group About Your Fit Out Project
Whether you are a tenant planning a CAT B fit out, a landlord looking to carry out a CAT A refurbishment, or simply at the early stages of planning and not yet sure which route is right for you, Shakery Group is happy to help. We offer free initial consultations and can provide feasibility input, space planning, and indicative costings before any commitment is made.
Call us on: 01376 617530
Email us on: enquiries@shakery.co.uk