What Are Interior Fit Outs? Everything You Need to Know


If you’re not in the construction industry, you will be forgiven for not knowing what an interior fit out is. However, if you’ve found yourself as part of a property development project, be that an office, prepping new builds for tenants or maybe even just doing up a property for yourself, you might have a lot of new terminologies you need to decipher.

Understanding what a fit out is will be important to the success of your project, which is why we’ve created this guide. Below, we’re going to explain this confusing industry terminology in more detail, what we mean by fit out, its purpose and the process of conducting a fit out.

Read on for the full explanation.

What is an interior fit out?

Let’s start with the basics; the term fit out refers to the process of taking an empty space and making the interior suitable for use. This includes any electrical, mechanical, plumbing or decorating that must be done to get the space ready for occupation. 

Primarily, the term interior fit out applies to commercial spaces, particularly office blocks. However, fit outs can also be required for domestic spaces too. It really just depends on what the property is being used for and who is conducting the fit out – which brings us nicely on to the next section.

Who completes the interior fit out?

Interior fit outs are typically carried out by specialist construction contractors. These could be arranged by the tenant, though most often, the contractor is hired by the developer or landlord in order to get the building ready for the tenant that is leasing it.

What are the different types of interior fit out?

To build on your understanding of interior fit outs, it’s important to know that there are three different types. The type you need will very much depend on the current state of the space, but the three categories are:

1. Shell and core

A shell and core interior fit out, as the name suggests, is needed if the space is an empty shell. This means it needs everything required to make the space useable. This type of fit out is usually orchestrated by the developers as they’re getting the building ready. 

2. Category A

A category A interior fit out is required for properties that have all the basics installed but still need important aspects, such as lighting and plumbing. This type of fit out is typically arranged by landlords when they need to get the space ready for a tenant.

3. Category B

The final option is a Category B fit out. This is only required if you want to design the interior to your own specifications. So essentially, all the basics are there, and the space is usable, but you want to make some bigger design changes. This type of interior fit out is often conducted by tenants.

What is included in an interior fit out?

We’ve briefly touched on elements such as lighting and plumbing, but what is actually included in an interior fit out? Well, most contractors will offer a large range of services and will conduct these according to the type of fit out it is (core, Cat A or Cat B). But in any case, a fit out could include:

  • Removals/strip outs
  • Flooring
  • Suspended ceilings
  • Lighting
  • Other electrical works
  • Partitioning walls
  • Joinery
  • Bespoke cabinetry and furniture installation
  • Decorating
  • Tiling
  • Wall cladding
  • Plumbing
  • Ventilation
  • Fire security

Again, what you require will depend on the current state of the property, but most contractors will offer a larger range of services like the above.

How is an interior fit out conducted?

In this final section, we’re going to break down the process of completing an interior fit out, starting from the brief, right down to the post-occupancy evaluation. A fit out is typically conducted as follows:

Consultation and design

The first thing that needs to be done is an initial consultation with contractors to agree on the brief and make sure they can conduct all the appropriate work. After this, the design team are employed to create designs based on the initial consultation and the client’s ideas.

Approving the plan

The next stage is checking on the feasibility of the project, making sure it’s possible. The client and the contractor make design and development changes where necessary before signing off on the final brief. The scope of the project is now set out.

Ensuring compliance

Before work can begin, the contractors and client must ensure that all planning permission and permits necessary for the project have been obtained.

The work is done

Next, the contractors will begin working on the project delivery, conducting the work and bringing in specialists where needed. At this stage, they bring the project design to life.

Post occupancy check

Last but certainly not least,  the client is walked around the completed space to check that everything is as it should be and that everything works. This is vital for checking that the design brief was met and that everything functions properly. The space is now ready for occupation.