Commercial Fit-Out: Cat A vs Cat B Cost Benchmarks

21 December 2025 · 8 min read · Cost Management

The distinction between Category A and Category B fit-out is fundamental to commercial office leasing, yet it remains one of the most common sources of cost disputes between landlords and tenants. Misunderstanding where one ends and the other begins can lead to six-figure gaps in budget expectations. For tenants taking a new lease — or landlords preparing a vacant floor — clarity on scope and current cost benchmarks is essential.

Category A: The Landlord's Baseline

Category A (Cat A) describes the standard of fit-out that a landlord delivers to make a floor or building ready for occupation. It is not a finished office. Rather, it provides the base infrastructure from which a tenant can build their own workspace. The precise scope of Cat A is defined in the lease or the heads of terms, but typically includes:

• Raised access flooring with bare finish, ready for tenant-installed floor boxes
• Suspended ceiling systems — typically mineral tile or metal raft, with basic lighting and mechanical services diffusers installed
• Mechanical and electrical distribution — ductwork, fan coil units, small power risers, and basic lighting (generally LED panels)
• Toilet blocks fitted out to a standard specification (sanitaryware, tiling, vanity units)
• Core areas including lift lobbies and circulation, finished to building standard
• Base building security — access control infrastructure, CCTV containment
• Compliance with building regulations and planning conditions

What Cat A does not include: partitions, floor finishes (beyond the bare slab or raised floor surface), tenant-specific lighting, kitchenettes, meeting rooms, furniture, audio-visual systems, or any branding elements.

Category B: The Tenant's Vision

Category B (Cat B) is everything the tenant adds to create their actual workplace. This is where the character and functionality of the office is defined. Typical Cat B scope includes:

• Partition walls — plasterboard, glazed, or operable wall systems
• Floor finishes — carpet tile, luxury vinyl tile, polished concrete, or engineered timber
• Decorative and feature lighting, including lighting control systems
• Kitchens, break-out areas, and tea points
• Meeting rooms and quiet rooms — including AV equipment, acoustic treatment
• Reception and branding elements
• Furniture, fixtures and equipment (FF&E)
• Tenant-specific data and IT infrastructure beyond landlord's base build
• Enhanced mechanical and electrical — additional fan coil units, local controls, supplementary small power

"The Cat A/Cat B boundary is where most lease negotiations get expensive. A clear, written schedule of what the landlord provides — down to the type of floor box and ceiling tile — prevents the most common disputes during dilapidations at lease end."

Cost Benchmarks and Drivers

Current Cat A costs in London range from £45–85 per sq ft, depending on the building grade and specification. Grade A new-build in zones 1–2 typically sits at £60–85/sq ft, while Grade B refurbishment in outer zones can be delivered at £45–55/sq ft. Outside London, expect £30–55/sq ft for equivalent specifications.

Cat B costs are far more variable because they reflect the tenant's choices. A standard specification — basic partitions, carpet tile, a modest kitchen, linear lighting — can be delivered for £60–80/sq ft. A high-quality Cat B with meeting rooms, feature lighting, biophilic design, acoustic treatments, and a substantial kitchen runs £100–140/sq ft. For Grade A space with premium materials and extensive AV, £140–180/sq ft is not uncommon.

Key cost drivers in both categories include:

• Mechanical and electrical complexity — high-density occupation with intensive cooling demands significantly increases costs
• Sustainability requirements — BREEAM Excellent or WELL certification adds 10–20% to fit-out costs
• Acoustic performance — acoustic ceilings, wall linings, and specially treated meeting rooms add up quickly
• Glazed partitioning — costs two to three times as much as plasterboard per linear metre

The Scope Boundary Problem

The most common commercial dispute in fit-out is overlap: items that could arguably sit in either Cat A or Cat B. Floor box installation is a classic example — is the box itself Cat A (installed in the raised floor by the landlord) or Cat B (installed by the tenant to suit their furniture layout)? Lighting control is another: does the landlord provide a full addressable DALI system, or just a basic switching arrangement?

The solution is a detailed Cat A specification schedule, agreed and attached to the lease. This should list every element, its specification, and which party is responsible. The same document then serves as the basis for dilapidations assessments at lease expiry.

Practical Steps Now

1. Request the Cat A schedule before signing heads of terms. If the landlord cannot provide a detailed specification, negotiate one as a condition of the lease.
2. Commission a measured survey and Cat B cost plan before committing to a fit-out budget. Early cost advice saves ten times its fee in avoided surprises.
3. Define your density and workstyle requirements — hybrid working has changed space ratios. Understand your actual desk-to-meeting-room-to-breakout ratio before specifying.
4. Review the dilapidations liability at lease inception, not at expiry. What you install in Cat B is what you may need to remove or reinstate.
5. Consider a Cat A-plus landlord package — some landlords now offer a 'managed Cat B' option, which can simplify delivery but limits customisation.

Sources: BCIS Online (2025); CBRE UK Office Cost Guide 2025; BCO Guide to Fit-Out (2024 edition); JLL Office Fit-Out Cost Survey; NorthEight project benchmark data from London and regional commercial schemes.