January's Callback Files: Five Fit-Out Mistakes That Were Written Into the Specification
Photo: SUNWHEAIW Shengaou, CC0, via Wikimedia Commons
There is a pattern to the post-completion snagging season. Christmas arrives, buildings run flat out through the cold snap, and by the second week of January our phone starts ringing with the same categories of complaint: meeting rooms that won't warm up, plant that trips out, valves nobody can reach without dismantling a ceiling.
Here is the uncomfortable part. In the majority of these cases, the installation was built exactly as specified. The failure was written into the documents at design stage, signed off, priced, and only became visible once real occupants met real winter. Five failures account for most of it.
Fail One: Plant Sized for the Drawings, Not the Building
The classic version: heating and cooling calculated from the fit-out drawings, with no allowance for actual occupancy, equipment loads or — crucially — the thermal performance of the landlord's base build. A fit-out designed for 45 people at 8 watts per square metre of small power, then occupied by 70 with servers in the comms room, will never hold temperature.
The specification fix: demand that the mechanical design includes a room-by-room heat gain and loss calculation based on agreed occupancy scenarios, with a stated diversity allowance, and require the designer to evidence plant margins of at least 10 per cent. Insist the calculation assumptions are included in the O&M documentation so future tenants inherit the logic, not just the hardware.
Fail Two: Controls That Don't Speak to Each Other
Landlord's BMS on one protocol, tenant's new air conditioning on another, lighting controls on a third — and three separate interfaces, none of which anyone on site understands. The building heats an empty floor because the tenant's system can't see the landlord's time clock.
The specification fix: require open-protocol controls (BACnet or Modbus) as a minimum, with a single points schedule showing every integration between landlord and tenant systems. Specify that the controls contractor demonstrates the integrated strategy to the facilities team before practical completion, and that as-installed control schematics are delivered — not just generic manufacturer literature.
Fail Three: Valves, Dampers and Actuators Buried Behind Fixed Ceilings
We open up ceilings in January and find isolation valves, motorised dampers and fan coil actuators completely inaccessible — sometimes above fixed plasterboard, sometimes behind a run of trunking installed after the services were signed off. Every future service visit becomes a ceiling survey. Unsurprisingly, maintenance gets deferred, and deferred maintenance in a sealed ceiling void is how water damage claims begin.
The specification fix: include a marked-up access and maintenance drawing as a contract deliverable, requiring access panels at every valve, damper, actuator and terminal unit, sized to permit removal of the component. Make the fixed ceiling contractor contractually responsible for coordinating with the services drawings before installation, not after.
Fail Four: Ventilation Designed Around a Strategy Nobody Revisited
Fit-outs frequently inherit the base build's ventilation regime and bolt on a meeting room or two without recalculating fresh air volumes. The result, once the floor fills up in winter: CO2 concentrations climbing past 1,500 ppm by mid-afternoon, complaints of drowsiness, and an air quality problem that no one can trace because the original design assumed half the occupancy.
The specification fix: require a ventilation adequacy review against the final layout and occupancy at design stage, with fresh air rates evidenced against CIBSE guidance for the intended use. Where demand-controlled ventilation is specified, ask for the sensor locations and control setpoints to be stated in the specification rather than left to the installer's discretion.
Fail Five: No Commissioning Time Left in the Programme
The most common fail of all, and the least technical. Commissioning is squeezed into the final fortnight, or the final week, or — in the worst cases — promised as a post-completion activity that never fully happens. The systems work, technically. They just don't work together, and nobody notices until the first sustained cold snap.
The specification fix: write commissioning into the programme as a protected activity with a minimum duration, require BSRIA commissioning procedures to be followed, and insist on a seasonal commissioning visit — ideally scheduled for October or November, before the first heating season, not after it.
The Common Thread
None of these failures required exotic technology or heroic sums to prevent. They required someone at design stage to ask how the building would actually be used, who would maintain it, and whether the documents said so. Landlords and tenants who specify with those questions in mind tend to spend their Januarys doing something other than taking our calls.
