The difference between Shell and Core, CAT A, CAT A+ / Plug and Play, and CAT B fit out

‘Fit out’ is the process of making interior spaces suitable for occupation. In office developments, the type of fit out depends on the landlord’s needs, and those of the tenant or occupier and their workforce. As the way we work continues to evolve, landlords need to think creatively about the tenants they can attract, and invest in a workspace that fits the bill. We can help.

New ways of working

In the past businesses traditionally chose office locations based on proximity to clients, historical location, transport hubs, marketing impact or even the CEO’s commute. But location decisions have become far more complex. Facilitating agile and flexible working, and improving employee wellbeing, have moved far higher up the priority list particularly given the post Covid world. Reduced headcount and an increase in remote working means that many businesses are now rethinking their property portfolios and demanding different functions and efficiencies for their workspaces.


Historically, office leases have been some of the most complex legal property documents – creating considerable time lags between making an offer, signing the lease, and tenants moving in, particularly in prestigious City Centre locations. In recent years, however, landlords, funds and investment firms have started adapting their approach. Dynamic, forward-thinking businesses refuse to accept 10 or 15-year leases and the obligations of their archaic legal documents. Early on, Regus-style offerings sprang up, where firms of any size could take furnished or unfurnished suites on short-term deals. This suited entrepreneurial start-ups, giving them the flexibility to expand or contract their workspace with the business. Next we saw Managed Offices, where a single operator would take care of all property, facilities, fit out and running costs for an occupier – for a monthly fee. More recently Plug and Play suites have grown in popularity, where – rather than just marketing space on a Cat A specification – landlords offer fully fitted and furnished suites on flexible terms. The Covid pandemic accelerated this change, and we’re now seeing a far more collaborative approach between landlords and their tenants.

The difference between Shell & Core, CAT A, CAT A+ and CAT B

Depending on the level of completion, and the occupant’s interior specification, there’s a range of fit-out categories to choose from – Shell and Core, CAT A, CAT A+, Plug and Play and CAT B. All are explained below. We’re highly experienced in all levels of fit out, so we can guide you through the decision-making process and even take care of the build – let’s talk.

Shell and Core

Shell and Core is the most basic condition in which to take space. It’s essentially a shell – a blank canvas without services (lights, air conditioning and so on) for the occupier and their fit-out partner to tailor as required.

Shell and Core usually comprises: the structure, cladding, base plant, completed common areas and external works. There may be main mechanical plant externally for a tenant to connect to, but this will be the tenant’s responsibility.

Sometimes the base-build perimeter walls will be plasterboard lined, taped and jointed, with windows and cills installed, but the occupier will be responsible for all other works. The responsibility of washrooms is generally decided on a site-by-site basis, depending on their access points (i.e. within office suite or communal).

Communal areas – which the landlord completes – will include:

● Reception(s)
● Lobbies
● Lifts
● Stairwells
● Loading bay

Why choose Shell and Core?

This category best suits businesses needing two or more large floorplates (a large floorplate being more than 1,500 sq m) that have bespoke layout or design requirements, or specifically need a highly cellular layout. Timing is fundamental to taking space in this condition. The building or refurbishment has to be at a point in which it is economically viable to pass control to a tenant.

The main benefits of Shell and Core for occupiers are:

1. The ability to totally craft the space to suit their needs.
2. Avoiding the cost of removing and altering landlord installations and fittings.
3. Faster access to site (subject to size of overall building and works elsewhere in the
4. Wider scope of bespoke mechanical and electrical solutions.

The landlord may also make a capital contribution equivalent to the fit-out budget (with the
occupier subject to a dilapidations clause at the end of the lease term requiring the occupier to reinstate to an agreed Cat A design).

Category A fit out

A step up from Shell and Core, Cat A provides a fully functional but empty space complete with basic installations and mechanical and electrical services (lighting, fire detection, air con) in place. There are no fixtures, fittings, partitions or conference rooms – these would be added under the Category B fit out. With no pre-lets in mind, architects and mechanical consultants can create a design that maximises the lettable space, with mechanical and electrical specifications designed to a general average occupancy level (according to Building Control Regulations and/or British Council for Offices guidelines).

There’s no standard industry definition for a Category A fit out, but your fully customisable space will typically include:

● Suspended or exposed ceilings
● Recessed or suspended lighting
● Mains power distribution to each floor
● Raised access floors
● Fully lined and decorated perimeter walls
● Air conditioning
● Local distribution board in riser
● Basic fire detection and protection systems

The landlord or developer will often make a capital contribution towards floor coverings and floor boxes.

Category A+ to Plug and Play

This is a relatively new concept but demand is growing. It bridges the gap between Cat A and Cat B fit out. To make vacant office suites more attractive to potential occupiers, landlords may consider carrying out some aspects of the fit out, such as a tea point, boardroom, Comms Room with full field data cabling etc all the way through to potentially fully fitting out and furnishing a suite. Either way this enables landlords to let their space quickly, and tenants who want quick occupation with some or all the facilities ready to go.

If the landlord decides that Plug and Play is the way to go, design is key, particularly in the post Covid return to work. The office workforce have higher expectations than ever before, partly thanks to the explosion of shared community workspaces offering practical design features, layouts that facilitate flexible working and collaboration. But post Covid people want a fresh, modern aesthetic with an emphasis on wellbeing and a residential influence to the design.

Entrepreneurial start-ups want somewhere modern, agile and tech-savvy that they can occupy quickly, with space to grow. A hassle-free, ready-to-occupy workspace in an attractive new environment that’s exclusively theirs, avoiding the need to share common areas with multiple companies.

We’re adept at helping landlords secure profitable occupiers fast, in the face of strong competition – by creating visually impressive, flexible and functional Cat A+ Plug and Play offices ready for immediate use. Get in touch.

Category B fit out

This is where the space is fully fitted out and tailored to the tenant by the tenant. A bespoke design will include corporate identity, communications, technology, departmental layouts, client experience elements and staff facilities such as well-being, break out spaces etc.

Physical elements include:
● Partitioning (glazed, solid or bespoke)
● Joinery (typically around Reception, the tea point/kitchen, and meeting areas)
● Door and floor finishes
● Meeting and conference rooms
● Workstations
● Breakout areas
● IT & Audio visual equipment
● Specialist lighting
● Alterations to the Cat A mechanical systems (to suit occupier layout)
● Furniture
● Branding such as signage, specialist finishes, frosted glass, and vinyl graphics
● Acoustic treatments and biophilia (to enhance wellbeing)

Next steps

We specialise in creating workplaces that people want to spend time in. So whether you’re looking for a new space, keen to transform your current workplace, or you need to attract quality tenants fast, we can help. We’re experts in workplace transformation and we want to help you create a space where everyone can thrive.

Take a look at some of our recent projects.

We help tenants find or build suitable workspaces based on in-depth knowledge and workplace assessments.

We help landlords create competitive workspaces that attract quality tenants.

With decades of experience in workplace design and build, refurbishment, renovation and fit out, we provide expert help with:

Workplace consultancy
● Space planning and rationalisation
● Interior design
● Designing for flexible working
Wellbeing at work
● Lease and purchase of real estate
● Sub-division and grey space
● Clean air and sustainable heating/cooling solutions
● Dilapidation and refurbishment
● Renovate vs relocate

Get in touch

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