The commercial property sector has a catastrophic waste problem. For years, developers have built office buildings to the category-A (cat-A) fit-out standard – preparing the space to a functional shell stage – to make spaces market ready. But by the time the first tenant moves in, much of that pristine cat-A fit-out is heading straight for the skip.

Dominic Williams is design director and head of interiors at Corstorphine & Wright

The rationale behind cat A is understandable. A working space is easier to market and lease. Funders, planners and local authorities expect buildings to reach practical completion (PC) and be technically habitable; lights must work and building systems be up and running.

However, studies suggest up to 60% of a cat-A fit-out is discarded when tenants bring in fit-out teams to create branded environments tailored for their end users. Brand-new mechanical, electrical and plumbing (MEP) and lighting systems may never even be switched on. Once removed, these systems’ warranties are void, resale is impractical and disposal is often the only option.

This generates a huge cycle of waste that is environmentally and financially indefensible. Landlords can spend large sums on cat-A fit-outs, only for tenants to spend again to remove and redo it all. In a market striving for efficiency, this double-spend culture is arguably one of the industry’s most avoidable inefficiencies.

The issue is not just about design. The requirement to achieve PC, to satisfy funding and compliance protocols, locks in waste. We are building spaces to an arbitrary level of completion that does not align with how offices are occupied. It is a procedural box-tick that produces tons of redundant material before the doors to the building even open.

Bad fit: cat-A fit-outs provide a functional blank canvas for occupiers, but incoming tenants often replace the existing heating, lighting and ventilation systems before they are even used

Yet the pressure to provide space ready for use persists, even when everyone involved knows elements of the cat-A fit-out are temporary at best. The mismatch between certification processes and operational realities has created a cycle of waste that feels increasingly out of step with an industry committed to net zero and circular principles.

However, this is not an unsolvable problem. There are clear, actionable ways to rethink the cat-A paradigm.

Circular economy

One promising avenue is adopting a circular economy approach. Rather than fitting out and ripping out, we can design for adaptability and reuse. Corstorphine & Wright has just completed a Northamptonshire office building that can be disassembled and reused at the end of its life. Elements such as lighting tracks, raised floors or partition systems and interior finishes can be specified with disassembly and redeployment in mind. But to do that effectively, we need material passports – digital records of the origin, specification and lifecycle of each element – so they can be reused, reinstalled or resold, not scrapped.

We must also question what it really means for a building to be complete. If the systems we install never serve their intended use, can we call that completion? The property sector is rightly under scrutiny for its carbon footprint, so redefining PC could be one of the most impactful shifts we make. Developers, investors and local authorities need to collaborate to modernise outdated completion criteria. A revised framework recognising modular, reconfigurable or pre-certified systems could maintain accountability without mandating unnecessary waste – and save a lot of money.

For designers pursuing low-carbon construction and circular principles, addressing the cat-A waste issue is a critical next step. It is an example of how entrenched practices can undermine sustainability. If we can move away from the reflex of ‘fit out to rip out’ and towards adaptable, circular approaches, we won’t just cut waste – we’ll unlock a new definition of quality rooted in longevity and genuine efficiency.

Dominic Williams is design director and head of interiors at Corstorphine & Wright