Cat A vs Cat B Fit Out: What’s the Difference?

When you start looking for commercial office or gym space in the UK, you’ll quickly come across the terms “Cat A” and “Cat B” fit out. These categories describe the condition of a commercial space and how much work is needed before you can move in and start trading. Understanding the difference is essential for budgeting your project correctly and knowing exactly what your landlord is — and isn’t — responsible for.

Here’s a plain-English guide from the team at Design Business Interiors, who have delivered Cat A and Cat B fit outs for commercial clients across the UK for over 30 years.

What is a Cat A fit out?

A Category A fit out (often written as Cat A) is the base level of finish that a landlord provides to make a commercial building ready to market to tenants. Think of it as a blank canvas — clean, functional, and safe, but with no personality or branding whatsoever.

A Cat A fit out typically includes:

• Raised access flooring
• Suspended ceilings with integrated lighting
• Mechanical and electrical services (heating, ventilation, air conditioning)
• Basic fire detection and safety systems
• Toilets and common area finishes
• Painted walls and basic floor finishes

A Cat A space is ready for a tenant to view and imagine how they might use it — but it is not ready to work in. You couldn’t move your team in on a Monday morning and expect to be productive. There are no desks, no partitions, no meeting rooms, no kitchen, and no branding.

What is a Cat B fit out?

A Category B fit out is what transforms a Cat A shell into a functioning, branded workplace. This is where the real design work happens — and where most of the spending occurs. Cat B is almost always commissioned and paid for by the tenant.

A Cat B fit out typically includes:

• Internal partition walls and glazed offices
• Meeting rooms, boardrooms, and breakout areas
• Reception area and front-of-house design
• Bespoke joinery, fitted kitchens, and tea points
• Workstations and furniture
• IT infrastructure, cabling, and AV equipment
• Specialist lighting, feature ceilings, and décor
• Branded graphics, signage, and feature walls
• Bespoke flooring — carpet, LVT, polished concrete

A Cat B fit out is what gives your workspace its identity. It’s the difference between an anonymous office and a space that genuinely reflects your brand, culture, and way of working.

What about Cat A+?

You may also come across the term “Cat A+” or “plug and play”. This is a hybrid offered by some forward-thinking landlords who want to attract tenants quickly. A Cat A+ space sits between Cat A and Cat B — it typically includes furniture, meeting rooms, breakout areas, and basic IT infrastructure, allowing a tenant to move in immediately with minimal additional investment.

Cat A+ is particularly popular with SMEs on short leases and companies that need to move quickly. However, it lacks the bespoke brand identity that a full Cat B fit out delivers.

Who pays for Cat A and Cat B?

In a standard commercial lease arrangement in the UK:

• Cat A is paid for by the landlord as part of making the property marketable and lettable
• Cat B is paid for by the tenant — it’s your investment in making the space work for your business

When negotiating a lease, it’s worth discussing a rent-free period or a landlord contribution towards your Cat B fit out. Many landlords in today’s market will offer a capital contribution in exchange for a longer lease commitment.

What does a Cat B fit out cost?

Cat B fit out costs in the UK range considerably depending on specification and location. As a guide for 2026:

• Basic Cat B: £40–£65 per sq ft
• Mid-range Cat B: £65–£100 per sq ft
• High-spec Cat B: £100–£160+ per sq ft

In the North West of England, where Design Business Interiors is based, costs tend to sit at the lower end of these ranges compared to London and the South East — making it excellent value for businesses in cities like Manchester, Liverpool, and Leeds.

Do I need Cat A or Cat B — or both?

If you’re taking a lease on a newly developed commercial building, the landlord will usually have completed the Cat A works. Your job is to commission the Cat B fit out that makes the space your own.

If you’re taking on a space that was previously occupied by another business, you may find it in a stripped-back condition — somewhere between Cat A and nothing. In this case, you may need elements of both, and a good fit out contractor will assess what’s there, what’s reusable, and what needs replacing.

At Design Business Interiors, we specialise in full Cat B design and build — we take responsibility for the entire process from initial concept through to handover, managing your project on time and on budget.

Ready to plan your Cat B fit out?

Whether you’re fitting out an office, a gym, or a commercial leisure space, our team at Design Business Interiors has the expertise to deliver. Get in touch for a free consultation — we’ll assess your space, discuss your brief, and give you a clear picture of costs and timescales.