Do you know your Cat A from your Cat B, or your fit out from your refurbishment? Read on and we’ll decode the jargon so that you can focus on your project, rather than tip-toeing around the terminology!

What is fit out?

This is the end-to-end process of making an internal space suitable for occupation. It’s the transformation of a concrete shell into a working space; from installing facilities (like the loo!) and raising the flooring, to installing team breakout areas, meeting rooms and workstations.

Often new office spaces will be provided as a blank canvas, in what we call a Shell and Core or a Cat A fit out. This leaves it up to the tenants to provide themselves with a working finish in what’s known as a Cat B fit out.

Here, we take you through each level of fit out and what you can broadly expect in your space.

Shell and Core

A shell and core fit out is the bare bones of a building’s interior space and is often how the building is provided by the developers. The building may be complete on the outside but on the inside the office space is just a shell, looking like a bare construction site; with concrete floors and walls, but with no lighting or facilities.

Although the office space is a bare shell, the common areas shared between tenants will be completed; like the lifts, toilets and building reception. Unlike the shell, these core areas are usually finished to a high standard and will be ready for incoming tenants.

What is a Cat A fit out?

While there’s no standard specification, Cat A spaces (also know as Category A fit outs) are usually finished with a suspended ceiling, lighting, heating, and raised flooring. This would be the functioning space that landlords would lease, leaving it up to tenants to install the functional design and finishes that suit their workplace through the form of a Cat B fit out.

It’s all pretty basic, but it’s a habitable space and usually with no concrete in sight! If you’re thinking all you need to do now is move in and furnish the space, you might want to think twice.

While a Cat A space could technically be habitable, they are often a bare-bones, open-plan finish that’s then treated as a blank canvas for interior and office designers. We wouldn’t recommend moving straight into a Cat A space, as you won’t have your funky breakout area, meeting rooms or cosy kitchen to sit down with a cuppa. For this, you’ll need to install a Cat B fit out.

What’s usually included in your Cat A fit out:

  • Raised floors and suspended ceilings (with a basic finish)
  • Basic mechanical and electrical services
  • Fire detection services and smoke alarms
  • Air-conditioning and ventilation (HVAC)
  • Basic internal finishes

What is a Cat B fit out?

Cat B (also known as Category B fit out) follows on from a Cat A fit out to provide a space that your company can simply move into and start working. Since this is something often tailored to your brand, these are usually left for the tenant to design and install.

There’s a lot of work that goes into transforming the blank canvas of a Cat A fit out into a functioning Cat B space. A Cat B office fit out would ideally be tailored to the individual needs of your business and workforce, delivering the right mix of workstations, breakout areas and meeting rooms. Space planning and workplace consultancy are often done before any design work is started to understand how employees are using their desks and meeting rooms, ensuring that the new design is a suitable fit for the workforce.

A tailored Cat B fit out should also reflect your brand and work ethos; including furniture and custom design elements that embody your corporate personality. This isn't just about choosing desks and furniture, but about ensuring that your office is somewhere that your employees will love to work; all while helping you attract and retain your industry's best talent.

What’s usually included in your Cat B fit out:

  • Fully-fitted kitchens and non-communal office amenities
  • Partitioning; including meeting rooms, offices and breakout spaces
  • Workstations and furniture
  • Re-routing airconditioning and power points
  • IT installation and infrastructure
  • Design and brand detailing


If you’re about to sign a lease for a new office space as either a Shell and Core or a Cat A, make sure you understand exactly what will be included. In the industry, there’s no universal standard as to what is included in each level of fit out, and one landlord’s idea of a Shell and Core or Cat A may be very different to another. Depending on your lease agreement, some landlords may require the premises to be returned to its original state upon the termination of your tenancy.

If you need any more help or advice at any stage of your office fit out project, feel free to give us a call and we can talk you through it.