Shell & Core, CAT A & CAT B Fit-Out – What’s the Difference?

Jan 20, 2023

There’s a lot of terminology thrown around in the office fit-out world. 

When taking a lease on a new office space, whether it’s your first time or you’re an experienced leaser, you may find yourself a little perplexed when faced with a choice between shell & core, CAT A and CAT B fit-outs; what on Earth do they mean, and which one is right for you?

Fortunately, we’ve created this handy quick guide to fit-outs, meaning that you can get to grips with the different types, and make an educated decision based on your unique needs.

But before we get started, there’s one key question to answer first…

What is a fit-out?

A fit-out is a term that describes the process of making interior spaces suited for occupation. In many cases, you’ll see it in an office context. A developer will complete the base construction, leaving the landlord to complete fit-out to a usually to a legal minimum requirement (e.g. fire detection and sounders, basic lighting and air handling. 

Final fit-out is usually carried out by the incoming tenant (who will also be required to strip-out the works at the end of the tenancy (also known as dilapidations – see separate blog)

If we were to imagine a building as a person:

The developer assembles the bones of the building (shell & core).

The landlord provides the skin (CAT A).

The tenant brings the clothes, dressing our person (CAT B). 

While quite a visceral way to imagine fit-outs, we find that this is the easiest way to remember each individual element.

With that out of the way, it’s time to jump into the nitty-gritty!

What is shell & core fit-out?

The shell and core fit out describes the basic internal framework of a building – the bare essentials.  

At this stage, an office building will appear complete from the outside, however the space inside will just be an empty shell. Works generally included are the structure, external cladding, base plant, completed common areas and external works (hard landscaping, planting etc) – the minimum required to achieve Building Regulations approval.

If a developer is planning to hand over a project in this state, expect to see only raw finishes; concrete floors and exposed ceilings – the skeleton of our fit-out human.

A shell & core fit out may have shared areas completed:

  • Doors & ironmongery 
  • Lobbies
  • Stairwells
  • Lifts
  • Stairwells
  • Washrooms (to basic spec)

We highly recommend checking with the developer so that you know exactly what is included. You don’t want any nasty unfinished surprises when it comes to our next stage of fit-out.

What is a CAT A fit-out?

The category A (Cat A) fit-out is usually undertaken for the landlord or building owner. The main objective for this type of fit-out is to remediate anything left by a previous occupant, and to prepare the space for market – increasing its appeal to any prospective tenant.

CAT A scope of work generally includes:

  • The installation of mechanical and electrical services (but generally only to a minimal level)
  • The installation of new air conditioning systems (but not always fresh air systems)
  • Raised access floors and ceilings
  • Basic fire detection & sounders/intruder alarm systems
  • General decoration to the perimeter walls
  • Floor coverings

You’ll likely see the building’s common areas and services such as stairs, lobbies, lifts, washrooms/showers and main entrance/reception area also updated as part of a CAT A fit-out. 

The landlord may make a contribution to the tenant for the carpets and floor boxes, and may offer an incentive or inducement towards the CAT B fit-out costs (known as the ‘Landlord’s Capital Contribution to Tenant’s fit-out works’).  

When related to the human we’re building, CAT A fit-out provides the skin; the building is a far more finished product than it was after the shell & core fit-out, but it isn’t fully ready to go out yet.

This brings us onto our third category – CAT B.

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What is a CAT B fit-out?

A CAT B fit-out describes all works required to take the blank canvas of any prospective space and make it fit the needs, aspirations and personality of the tenant’s organisation. It’s the dash of personality every business needs to make their building their own. 

A successful Cat B fit-out will accommodate the tenant’s current needs, together with any predicted changes that may occur within the duration of the lease.  

It will reflect the culture and brand of the organisation, and will create the ideal working environment in which the business, its culture and people can thrive.

CAT B scope of work covers many things, from staff wellbeing facilities to collaborative working areas; the goal of CAT B is to create an environment where productivity & wellbeing are optimised.

This means that CAT B includes (but isn’t limited to):

  • Installation of partitioning, glazing and internal joinery
  • Adjustments to mechanical & electrical services to suit layout changes (e.g. air conditioning, lighting & switches)
  • Installation of data cabling and floor boxes
  • Ceiling details/bulkhead designs
  • Feature lighting
  • Custom branded decoration 
  • Graphics to walls, ceilings & floors, and glazing
  • Floor coverings
  • IT & Audio-visual equipment
  • Window blinds
  • Custom joinery – reception desks, kitchens, break-out bars etc
  • Storage wall and lockers
  • All loose furniture 
  • Illuminated signage

The end result will deliver a working environment which is functional, adaptable and unique, and supports a client’s business needs and future goals.  

Bringing it back round to our ongoing analogy, this is where we ‘dress’ our building, giving it the clothes it needs to make it the ideal workspace for your team.

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What is CAT A Plus?

One final option that we’ll quickly cover is CAT A Plus, a newer, more specific style of fit-out that blurs the lines between CAT A and CAT B fit-outs. 

CAT A Plus is designed for tenants who want to move into a building that’s fully furnished and ready to go. While CAT B fit-outs are there to provide the ideal, fully tailored working environment for a tenant, CAT A Plus is designed to ensure tenants can move in in as short a time as possible. 

This is an option for businesses who need to move in quickly, or smaller businesses who want to avoid the longer-term investment that a CAT B fit-out brings. CAT A Plus provides all the basic amenities the tenant will need to get settled in.

There is one very important consideration we ought to leave you with – none of these categories have standard definitions. 

One developer’s interpretation of a shell & core fit-out may differ significantly from another’s. We highly recommend that, when preparing to sign a lease for a new office space, that all parties are in agreement as to exactly what will be included at every stage. 

Need further advice? Our specialists at Rhino are here to help. 

An office fit-out is a significant undertaking; there’s a lot of moving parts and things that could go wrong – it’s completely understandable if you’re a little nervous!

Get in touch with our interior office design team today for bespoke, impartial advice. We’re here to ensure your next fit-out goes as smoothly as possible. 

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