Cat A vs Cat B Office Fit-Out: What to Visualize at Each Stage

If you brief an office render without being clear which fit-out stage you are at, you usually get the wrong asset. Cat A, Cat A+ and Cat B are not interchangeable, and each one calls for a different kind of CGI. We render these for design-and-build firms most weeks, so here is the practical map across all 3 stages: what each one is and what is actually worth visualizing.

A quick framing first. These categories describe how finished an office is, from a bare landlord shell up to a tenant's complete workspace. These terms are standard across the UK market, but who pays for the render, and what it needs to show, changes at every step.

Cat A: the landlord's shell

Cat A is the base build a landlord delivers: raised floors, suspended ceilings, basic finishes, lighting and the mechanical and electrical services, but no actual workplace. It is a lettable blank canvas.

Honestly, Cat A is rarely the main CGI commission. When it does get rendered, the job is usually marketing: show the empty shell, then show how the same space could look with a scheme in it, so a prospective tenant or their agent can picture the potential. The render is selling possibility, not a finished design. That is a different brief from a tender image, and it is closer to property marketing than to fit-out work.

Cat A+: the landlord goes further

Cat A+ sits between the two. A landlord adds some amenity to the bare shell to make it easier to let: commonly a kitchen or tea point and a finished reception and entrance, sometimes 2 or 3 meeting rooms, so a tenant can move in with less to do. It has become more common as landlords compete for occupiers.

For CGI, Cat A+ is worth rendering precisely because it shows a head start. An image that makes the entrance and the amenity look ready to use is a strong leasing asset, because it shifts the tenant's mental maths from "what would this cost me to finish" to "I could be in here soon".

Cat B: the real fit-out

Cat B is the office itself: the tenant's layout, finishes, furniture, joinery and brand. This is where most of our work sits, because it is the scheme a design-and-build firm is pitching to win, and the one that decides a tender.

At Cat B the render has to be faithful. Our job is not to design the office; the D&B firm or interior designer does that. Our job is to show their scheme as convincingly and accurately as possible, so the client in the pitch room sees exactly what they will get. That means the real materials, the real brand colours, the real spatial feel, usually as a set of photoreal stills from around 700 pounds each at 4K and above, and, when the space needs to be felt in motion, an office walkthrough animation. You can see Cat B work on the Hickman in Aldgate and offices in Clerkenwell.

What to commission, by stage

Put simply: match the asset to the question you are answering.

If you are a landlord or agent trying to let space, you want Cat A or Cat A+ marketing renders that sell potential, often 2 or 3 looks for different tenant profiles. If you are a design-and-build firm pitching a fit-out, you want Cat B tender stills that prove your scheme down to the detail, plus a walkthrough for sign-off on the spaces that earn it. Briefing the right one saves a round of expensive rework.

Honestly, these lines blur on real projects, and a single building can need all three of these at different moments. What does not change is the principle: the render exists to answer one specific question for one specific audience, so decide whose decision you are trying to influence before you decide what to build. The full picture of how we approach this is on our office 3D visualization page.