CAT A vs CAT B: What They Mean and Why It Matters for Your Strip Out

August 25, 2026

strip out contractors

The stages of a commercial building, in order

It helps to see all the terms laid out together, because they describe points on a single spectrum from bare structure to finished office.

Shell and CoreDeveloper
The structure, external envelope, roof, core areas, lifts, stairs and main plant. Landlord common parts are finished. The lettable floors are bare concrete with capped off services. Not usable and not lettable to most occupiers without further work.
CAT ALandlord
Raised access floors, suspended ceilings, basic lighting, distributed mechanical and electrical services, fire detection, and a blank painted finish to walls. Functional and lettable but nobody can actually work in it yet. No layout, no rooms, no furniture.
CAT A+Landlord
Sometimes called plug and play. The landlord adds basic partitioning, a couple of meeting rooms, a tea point, floor finishes, furniture and connectivity. A smaller tenant can move in and start working immediately. Increasingly common in London as landlords compete with flexible workspace operators.
CAT BTenant
The tenant's own fit out. Layout, partitioning, meeting rooms, kitchens, breakout areas, branded finishes, joinery, IT infrastructure, AV, furniture and everything else that makes it a specific company's office rather than a generic one.
These are conventions, not legal definitionsThe British Council for Offices publishes widely used guidance on what each category should include, but CAT A and CAT B are market terms rather than defined standards. What counts for your building is the specification appended to your lease or building contract. Two buildings in the same street can be marketed as CAT A and have meaningfully different specifications. Always check the document rather than assuming the label.

What is actually included in each

CAT A

Usually landlord funded
  • Raised access flooring
  • Suspended ceiling grid and tiles
  • Basic lighting throughout, usually LED
  • Mechanical services distributed to the floor plate
  • Electrical distribution and small power
  • Fire detection and alarm systems
  • Fire sprinklers where required by the base build
  • Blank plastered and painted walls
  • Basic finishes to the demised area only

CAT B

Usually tenant funded
  • Internal partitioning and room layout
  • Meeting rooms and private offices
  • Kitchens, tea points and breakout spaces
  • Floor finishes such as carpet, vinyl or timber
  • Feature lighting and ceiling alterations
  • Data cabling and IT infrastructure
  • AV and meeting room technology
  • Joinery, reception desks and storage
  • Branding, graphics and decorative finishes
  • Furniture and loose fittings

Why this matters for your strip out

This is the part most CAT A and CAT B guides skip entirely, and it is the part that costs tenants money.

When your lease ends, your reinstatement obligation is usually expressed as returning the premises to CAT A condition, or to the condition recorded in the Schedule of Condition, or to the state described in your licence for alterations. In practice that means stripping out everything in the CAT B column above and putting back anything from the CAT A column that you altered or removed during your occupation.

That second half catches people out. Tenants think of reinstatement as taking things away. But if your CAT B fit out removed part of the suspended ceiling to expose services as a design feature, or took out sections of the raised floor, or reconfigured the landlord's lighting and mechanical layout, you are also liable for putting those back. Reinstating a CAT A element is often more expensive than removing a CAT B one.

Element Whose scope What happens at lease end
Partition walls you installed Tenant Removed, walls made good, floor and ceiling patched where partitions met them.
Carpet and floor finishes Tenant Lifted and removed. Adhesive residue on raised floor panels usually needs cleaning back.
Raised access floor Landlord Stays in place. But any panels you cut, removed or damaged have to be replaced to match.
Suspended ceiling Landlord Stays. If you removed sections for an exposed services look, you reinstate the full grid and tiles.
Lighting Landlord Original CAT A lighting stays or is reinstated. Feature and decorative lighting you added comes out.
Data cabling and comms Tenant Removed entirely, including containment and anything left abandoned in ceiling and floor voids.
Kitchen and tea points Tenant Stripped out. Water and waste connections capped off properly back to the riser.
Air conditioning you added Tenant Removed. Refrigerant recovered by an F Gas registered engineer, which is a legal requirement.
Fire detection alterations Depends If you moved or added detection heads to suit your layout, the system usually needs reinstating and recertifying.
The expensive mistakeTenants routinely budget for removing what they installed and forget about reinstating landlord elements they altered. Putting back a suspended ceiling grid across an open plan floor, or replacing cut raised floor panels to match an obsolete original system, can cost more than the entire soft strip. Get this into the scope at quotation stage rather than discovering it when the surveyor inspects.

The problem with returning to CAT A

Here is where it gets genuinely difficult. Your lease says return the premises to CAT A condition. Fine. But CAT A as at when?

If you took the space in 2010, the CAT A specification of the day might have included T8 fluorescent lighting, a particular raised floor system and a specific ceiling tile that is no longer manufactured. Reinstating that exact specification may be impossible or absurdly expensive. Meanwhile the landlord may argue the space should come back at current CAT A standard, which is a higher spec than what you were given.

Neither position is automatically correct. It depends on the lease wording, the licence for alterations and whether a Schedule of Condition exists. This is exactly the sort of thing that a dilapidations surveyor negotiates, and it is why appointing one early is worth the fee.

If a Schedule of Condition exists

You are in a strong position. The schedule records the actual state of the property when you took it, with photographs. Your obligation is limited to that baseline and you cannot be required to hand back something better.

If the licence for alterations is specific

Also good. A well drafted licence lists exactly what you installed and states clearly whether each element must be reinstated. Read it before planning anything, because some licences let you leave alterations in place.

If neither exists

This is the difficult scenario. The lease wording alone governs, and both sides will interpret CAT A to suit themselves. Get a surveyor involved early and gather any evidence you have of the original condition, including old photographs and the original fit out drawings.

If the landlord is refurbishing anyway

Worth exploring before you spend anything. If the landlord plans to strip the floor back and redevelop, Section 18 of the Landlord and Tenant Act 1927 may limit or eliminate what they can recover from you for works that would be pointless.

Strip out to CAT A versus strip out to shell

When you commission a strip out, be clear about the end point. These are two different jobs with different costs and different programmes.

A strip out to CAT A removes the tenant fit out and leaves the landlord's base build intact. Raised floor stays, ceiling stays, primary services stay. It is a more careful job because you are working around elements that have to survive undamaged, and any damage you cause becomes your problem to make good.

A strip out to shell removes everything down to the structural frame and slab. Ceilings out, raised floors out, all services stripped back to the riser. Faster per square foot because there is less to protect, and often what a landlord wants when they are planning a full refurbishment and a new CAT A themselves.

Ask this before accepting any quoteAsk the contractor to state in writing what condition the space will be in at completion, item by item. Does the ceiling grid stay or go? Are the raised floor panels being lifted or left? Is making good and redecoration included or priced separately? Vague scope is where disputes start, and clarifying it takes one email.

Questions we get asked a lot

The points that matter

CAT A and CAT B are useful shorthand, but they are conventions rather than standards. What binds you is the specification in your lease and licence for alterations, not what the industry generally means by the term.

  • CAT A is the landlord's lettable base. CAT B is your fit out on top of it
  • At lease end you usually remove CAT B and reinstate anything you altered in the CAT A base
  • Reinstating landlord elements you changed is often more expensive than removing your own
  • A Schedule of Condition is your strongest protection. If you have one, use it
  • Get any agreement to leave the fit out in place documented in writing before lease end
  • When commissioning a strip out, specify the end condition item by item rather than just saying back to CAT A