When organisations move into new office space, one of the first decisions they face is whether they need a cat a and cat b fit out and what each stage actually involves. The distinction matters because it directly affects fit out costs, move-in readiness, and how functional the workplace will be once employees arrive.
At Persy Booths, we work closely with organisations shaping their interior space and understand how decisions made during office fit outs influence productivity, collaboration, and employee experience. Whether starting with a shell and core office or upgrading an existing cat b office, understanding the fit out process helps avoid delays, overspending, and poorly designed work environments.
Key takeaways from this article
- Cat a prepares a space ready with core amenities and infrastructure, while cat b transforms it into a fully operational workplace.
- Cat b fit outs cost more but directly shape company culture, office layout, and employee experience.
- Hybrid working requires thoughtful cat b space planning, including quiet zones, breakout spaces, and collaboration areas.
- Lease terms and existing space condition strongly influence whether cat a, cat b, or combined fit out cat is best.
- Acoustic design, flexible layouts, and technology are now essential elements of modern office fit.
What Cat A and Cat B Fit Outs Include
A clear standard industry definition explains the difference between a cat a fit and cat b fit: "Cat a creates the base building infrastructure, while cat b delivers a finished, usable workspace".
Cat A Fit Out Meaning, Typical Specification and Who Pays
A cat a office fit prepares an empty shell so it becomes a lettable, functional office. It typically includes raised access floors, suspended ceilings, basic mechanical and electrical systems, HVAC systems, air conditioning, smoke alarms air conditioning, and basic internal finishes such as painted walls and concrete floors.
These elements form the core fit out and convert a shell and core office – usually a concrete and metal frame with minimal adjustments – into internal space suitable for occupancy. Landlords normally fund cat a fit outs because they create space ready for tenants without committing to specific office layout decisions.
The result is a functional office, but still a blank canvas or bare bones environment with limited usability for day-to-day work.
Cat B Fit Out Meaning, Features and Move-in Readiness
Cat b fit outs transform cat a space into a fully working cat b office. A typical cat b office fit includes interior partitions, meeting rooms, kitchen areas, break rooms, breakout spaces, furniture, soft furnishings air conditioning, IT infrastructure, infrastructure design, and brand detailing.
Cat b involves installing all functional elements required for a modern workplace – turning a shell and core fit into a complete working environment with electrical services, power points, shower facilities, and office design tailored to the tenant’s needs.
Cat A vs Cat B Fit Out: Costs, Timelines and Key Differences
Understanding cat a and cat b fit out costs and timelines helps businesses plan realistic move-in dates and avoid delays.
Scope, Responsibility and Category A / B (Plus Cat A+)
Category a focuses on infrastructure and base building elements. Category b focuses on customisation and usability.
Key differences include:
- Cat a – usually funded by landlord, delivers shell and core fit with building’s mechanical, electrical systems, and basic finishing
- Cat b – usually funded by tenant, creates a complete office environment with partitions, furniture, and brand detailing
- Cat A+ – a combined cat a cat b office fit out that includes ready-to-use features such as meeting rooms and simple office design elements
Choosing between cat a office fit, category b workspace, or combined fit out depends on lease terms, project budget, and required move-in speed.
Cat A and Cat B Fit Out Costs, Number of Days on Site and Move-in Dates
Typical commercial fit out costs vary depending on project complexity and specification. Cat a office fit is generally lower cost, focusing on infrastructure and core amenities. Cat b fit outs involve higher investment due to furniture, IT infrastructure, and interior partitions.
Programme length also differs. Cat a may take several weeks, while cat b can extend to months depending on design complexity. Cat b space is fully usable on completion, while cat a remains an empty space requiring further work.
Designing Cat B Fit Out for Hybrid Work and Company Culture
Modern workplaces require more than compliance. Cat b space decisions now shape how employees collaborate, focus, and experience the workplace. Modern research into office space and workplace performance shows that layout, flexibility, and workplace design strongly influence employee productivity and collaboration, particularly in hybrid environments.
Space Planning for Hybrid Working, Schedules and Office Occupancy
Effective office layout planning must reflect real usage patterns. Modern hybrid workplace design includes balancing desks with breakout spaces, collaboration zones, and quiet areas, using data to optimise occupancy and avoid underused space.
Organisations increasingly use insights from room occupancy sensor technology to refine layout and improve utilisation, alongside planning for flexible office space that adapts to changing workforce patterns.
Quiet Zones, Collaboration Areas and Office Noise Control (Booths, Pods and Portable Rooms)
Acoustic comfort is now essential in modern office design. Organisations increasingly combine quiet zones and collaboration areas to manage the office noise level and improve productivity, while also improving employee well being. Academic research shows that careful acoustic management to reduce office distractions helps lower cognitive stress amongst workers.
In open office environments, acoustic design also involves collaborative workspace planning and using office noise reduction solutions, while white noise machine strategies also help manage distractions.
Modern cat b office solutions adopt a flexible office space strategy, meaning that private office pods are made available for employees who need them. The size and format of these office pods – which are effectively portable meeting rooms dedicated to quieter work – depend on their intended use.
- An individual work booth or a soundproof phone booth is suitable for focused solo working or calls
- A two person phone booth is better suited to for private conversations
- A larger team meeting booth supports small group collaboration without distractions.
Choosing the Right Cat A and Cat B Fit Out Strategy for Your Project
Selecting the right fit out cat strategy depends on budget, lease responsibilities, and existing space condition.
Lease Responsibilities, Budget Planning and Risk of Over- or Under-Specifying
Fit out planning should consider lease terms defining landlord versus tenant responsibilities, cat a office fit out costs, cat b fit out costs, and existing shell and core office condition. Overspending on the wrong stage or under-specifying infrastructure can lead to costly redesign or poor usability.
Ensuring electrical systems, core amenities, and building reception integration align with operational needs is essential for successful commercial projects.
Aligning Fit Out with Company Culture, Employee Experience and Hybrid Working Success
Modern office fit should reflect how employees work and interact. Effective workplace design includes creating breakout spaces, collaboration areas, and even play space to support creativity and engagement. Interior space should encourage productivity while ensuring internal space suitable for hybrid work patterns.
A well-designed cat b office transforms new office space into a compelling environment worth commuting to, improving retention and employee satisfaction.
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