Most commercial occupiers face the same problem when their lease comes up for renewal: the office needs work, but the business cannot pause for three months while it gets done. The good news is that with proper planning, a Cat B fit-out can be delivered around a working business with minimal real disruption. The bad news is that proper planning is far rarer than it should be.
This is the playbook we use on commercial fit-outs in occupied space.
Phasing: The Single Most Important Decision
Almost every successful occupied fit-out comes down to a well-thought-out phasing plan. The principle: never disrupt more than 20 to 30 percent of the floor at once, and always have somewhere viable for displaced staff to work.
For a typical 10,000 sq ft office, this usually means dividing the floor into three or four zones and working through them in sequence over 8 to 12 weeks. The zones are sealed off with full-height temporary partitions (not screens) to contain dust and noise. Air handling and access are isolated where possible.
Out-of-Hours Working
Some elements simply cannot be done in occupied hours: structural work, heavy demolition, anything requiring loud cutting or grinding, ceiling reconfigurations involving sprinklers or services. We schedule these for evenings (6pm to 11pm) or weekend shifts.
The cost of out-of-hours working is real (typically a 30 to 40 percent labour premium), but it is far smaller than the cost of business disruption. On a £400,000 fit-out, allocating 25 percent of the labour to out-of-hours might add £25,000 to the project. The cost of having 60 staff unable to work for two days is comfortably more than that.
Communication with Staff
The single biggest source of complaint on occupied fit-outs is not noise or dust. It is uncertainty. Staff need to know, every week, what is happening, where, and what to expect. We provide weekly bulletins to the client, who circulates them internally, and a clear point of contact for any issues.
On larger projects, we hold a brief weekly drop-in for staff to ask questions directly. Most people who feel involved cope with disruption far better than people who feel they are being kept in the dark.
Air Quality and Cleaning
Construction generates dust. The two ways to manage it in occupied space: prevent it from spreading, and clean what does spread. Full-height polythene sheeting with sealed edges, negative-pressure HEPA filtration on demolition zones, and daily deep cleans of all common areas. We provide air-quality monitoring on request.
Building Management Coordination
In multi-tenant buildings, the building manager is your most important ally. Early engagement (ideally 8 weeks before mobilisation) lets you agree access routes, lift bookings, out-of-hours working permissions, hoarding locations and waste removal logistics. Skipping this step is the most reliable way to lose two weeks of programme.
Snagging in Occupied Space
Snagging on an occupied fit-out is harder than on an empty shell because clients are using the space as it is finished. We snag each zone before handing it back to the client, and run a final defects period of 12 months after completion. Most issues are minor (paint touch-ups, door adjustments) and can be addressed during occupied hours with minimal disruption.
"On any occupied fit-out, the contractor's job is half construction and half choreography. The clients who get the best result are the ones who treat phasing and communication as critical, not as overhead." Sara Lopez, Quantity Surveyor.