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What’s the difference between a CAT A and CAT B fit-out?

There’s a lot of jargon attached to commercial fit-outs, which can make this area of workplace design and refurbishment difficult to navigate. We unravel the technical terms, from CAT A to Shell and Core fit-outs, turning you into an expert on this topic. Here we cover: 

  1. What an office fit-out is 
  2. The difference between CAT A and CAT B fit-outs 
  3. The definition of a Shell and Core fit-out
  4. What a CAT A fit-out involves
  5. What a CAT B fit-out involves
  6. The definition of a CAT A Plus fit-out 
  7. What’s meant by a plug and play fit-out

Never feel confused again when it comes to commercial fit-out terminology, and know exactly what to expect from your fit 

1. What is an office fit-out?

An office fit-out is when a commercial space is developed to suit the needs of its owners or occupiers. This space is often an empty shell of a building. The tenant or landlord may work closely with a team of designers and developers to execute the commercial fit-out according to their vision for the workplace, making sure it’s fit for purpose and aligned with the tenant’s brand, working style and culture.  

2. What is the difference between a CAT A and CAT B office fit-out?

CAT A and CAT B office fit-outs both refer to design and build projects in commercial properties, but the work involved is different.  

For example, CAT A fit-outs result in a blank canvas an interior designer can work their magic on to create a habitable office. Meanwhile, CAT B fit-outs incorporate that which makes a space functional as well as the elements needed to bring an occupant’s office to life (such as furniture and branding). We look at these differences in more detail soon. Note that CAT A works are often modified during the CAT B works; both projects can be completed in parallel to reduce timescales, budgets and waste.  

3. What is a Shell and Core fit-out?

A Shell and Core fit-out takes place before a CAT A and CAT B fit-out. It involves installing or updating the infrastructure of the building in question, specifically areas relating to the concrete and metal frame, such as: 

  • Lift shafts 
  • Lobbies  
  • Loading bays  

The term “Shell and Core fit-out” can be misleading – it sits within the fit-out spectrum but technically describes the state of a building before any fit-out occurs. The space isn’t usable at this stage, it has most likely just been constructed. It may look complete from the outside, but inside things like lighting, flooring and air-conditioning won’t be installed. 

4. What is a CAT A fit-out?

CAT A is short for Category A. It’s a commercial fit-out project where the end product is a functional yet empty space interior designers can transform into a bespoke office based on the occupant’s vision and objectives.  

 A typical CAT A fit-out is completed on behalf of a landlord. Usually, they’re looking to turn an empty space into a desirable building to help them secure new, high-quality tenants.  

We’ve completed many CAT A fit-outs for landlords, like the Redde Northgate project in Bath. The building had been unoccupied for a few years, and the landlord wanted to reinject life back into the space. In this case, we carried out a Shell and Core fit-out first, which involved installing a new lift.  

 For the CAT A fit-out, we made sure all the necessary infrastructure and finishes were in place for subsequent design work. This included: 

  • Hot and cold-water feeds 
  • Lighting with daylight dimming 
  • A new Building Management System (BMS) 
  • A new Air Handling Unit (AHU) and a Mitsubishi 3 pipe Virtual Routing and Forwarding (VRF) system 
  • Toilets and shower facilities 
  • A new Bauder single-ply roof 
  • A glass roof in the atrium 

 CAT A fit-outs can also feature things like raised access flooring, fire detection systems and painted walls.  

5. What is a CAT B fit-out?

CAT B is, you guessed it, short for Category B. Unlike CAT A fit-outs which are typically undertaken on behalf of the landlord, CAT B fit-outs are often commissioned by the tenant who’s seeking to either turn an empty space into a finished office or overhaul an existing workspace, the latter of which is known as a CAT B refurbishment. 

CAT B fit-outs ideally begin with a period of workplace strategy consulting and space planning. This is to make sure the fit-out is tailored to the tenant’s vision, brand, culture and business goals. A designer will look at everything from the number of teapoints needed to the colour of the plant pots in reception.  

At Interaction, we carefully consider the tenant’s long-term goals when approaching a CAT B fit-out. For instance, we recently helped Immersive Labs create a collaborative workspace that housed their ambitions – to increase headcount from a team of 40 to a team of 500 over three years. 

The project featured a curved building which made for some tricky but exciting design decisions (which you can read about in our case study). Ultimately, to realise the tenant’s vision for an immersive, characterful and collaborative office, the CAT B fit-out included things like: 

  • A dining and social area with a top-of-the-range kitchen 
  • Collaborative meeting spaces with mobile tables and an auditorium 
  • Individual quiet rooms, a wellness room and a soundproof podcast room 
  • A yoga studio, an enclosed games room and a concierge bar 
  • Fun decor such as bean bags, sweet machines and flexible lounge furniture  
  • Exposed flooring to allow for a dedicated scooter pathway 
  • An abundance of natural light acess 
  • Installing preserved foliage into the office walls 
  • Bespoke joinery throughout 

 This gives you an idea of what a CAT B fit-out can entail. In the end, these projects should result in an environment that brings out the best in the people using the space every day; a place that makes them feel happy and helps them excel at work.  

6. What is a CAT A Plus fit-out?

A CAT A Plus (or CAT A+) fit-out again results in a blank canvas ready for some stylish interior design. Except this time basic amenities and furniture are provided, from desks and dining tables to fridges and coffee machines. 

This means the tenant can move in quickly and easily; all they need to bring with them are their employees, IT equipment, potted succulents and anything else that will make the office theirs. For this reason, CAT A Plus fit-outs appeal to smaller businesses seeking fewer upfront costs.  

With this unique type of commercial fit-out, the landlord can often use the same furniture and equipment for the next tenant. This makes moving tenants more efficient while also reducing waste, which has the added benefit of increasing sustainability. 

7. What is a “plug and play” fit-out?

A “plug and play” style fit-out is often undertaken by a landlord to create a space immediately ready for a tenant to take over. Being able to offer a pre-fitted workspace to potential tenants speeds up tenant acquisition, reduces rent voids and provides landlords with a convenient and reliable competitive advantage in a rapidly-changing market. Interaction’s Primed service offers just this, with an experienced team creating fast-turnaround, high-quality spaces ready for tenants to call home.

Need advice on a commercial fit-out?  

Call us on 01225 485 600 and tell us about your upcoming fit-out project. You can also explore our office fit-out services at your leisure. Also, make sure you bookmark this guide in case you forget your fit-out terminology and need a refresher. 

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