The Float Everyone Wants
You are the planner on a £9m school extension. The baseline programme shows practical completion in week 44 with 10 days of total float on the roof works, which sit on the critical path only through a shared crane. The main contractor's package programme uses that float to absorb a late steel delivery. Separately, the M&E subcontractor has told you it intends to use the same float for its riser installation. The client has a fixed opening date in week 44. The crane is booked for weeks 18–22 only.
1. Who owns the float, and what happens if both parties use it?
Read the worked answer
Float ownership depends on the contract; many forms are silent, and the default position is that float is a shared project resource, not a party's property. The practical answer: if both the main contractor and the M&E subcontractor consume the same 10 days, the roof works and riser installation collide on the shared crane in weeks 18–22, and the 10 days is gone twice over.
Reasoning:
- The float is not additive. Ten days used by one party is ten days unavailable to the other.
- Because the crane window is fixed (weeks 18–22), a collision there is not recoverable by resequencing later work.
- The client's week 44 date is then at risk with no float left.
Conclusion: the float must be allocated explicitly, in writing, before either party relies on it.
2. What should you do as planner to protect the week 44 date?
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- Quantify the collision: map both parties' use of the crane window against the 10-day float and show the combined effect on week 44.
- Allocate the float in writing: agree with the main contractor and M&E sub who may use it and for what, and record it in the programme notes.
- Protect the crane window: treat weeks 18–22 as a constraint; any slip into it needs a recovery plan, not a float claim.
- Add a recovery option: identify a resequencing or second-crane option with cost, so the client can see the price of protecting week 44.
- Report to the client with the risk stated plainly rather than presenting week 44 as safe.