An allowance that nobody is watching
The contract bill carries provisional sums for things that could not be designed or priced at tender: the specialist lift installation, the external lighting, an allowance for contamination if found, a contingency for works to the existing structure. Each is a line with a figure. As the job goes on, the architect instructs against them, the contractor obtains quotations, specialists are appointed, and invoices come in.
Each of those steps is recorded somewhere: the instruction in the architect's file, the quotation in an email, the order in the contractor's system. What nobody has is a running view of how much of each sum is committed, how much is spent and what the outturn will be. The first time anyone adds it up properly is often the final account, and the answer is a surprise.
Why the sums get away from you
- Instructions against provisional sums are not always labelled with the sum they draw on.
- Quotations and orders are held by the contractor, and you see them late.
- Some instructions draw on more than one sum, or on a sum and a variation, and the split is not recorded.
- The cost report shows the original allowance until someone remembers to adjust it.
- Omitting the unspent balance of a sum is left until the end.
The arithmetic is simple. Keeping it current across a dozen sums and a steady flow of instructions is what fails.
What an unwatched ledger costs
Clients see a cost report that looks settled while real overspends build up inside the provisional sums. Contingency is spent twice, once in the client's mind and once on site. Final accounts take longer because each sum has to be reconstructed from instructions and invoices. And the conversation about an overrun happens when it is too late to change anything.
| Provisional sum | Today | With the ledger |
|---|---|---|
| Allowance | Line in the contract bill | Held with its description and conditions |
| Instructions against it | Architect's file | Linked, with the amount drawn on this sum |
| Quotations and orders | Contractor's emails | Attached as they arrive |
| Committed and spent | Unknown until the end | Running totals by sum |
| Forecast outturn | Guessed in the cost report | Surveyor's forecast recorded with a note |
The ledger we build
- Each provisional sum and prime cost sum is loaded from the contract bill with its allowance, description and any conditions noted by your surveyor.
- Instructions are read from the project mailbox or instruction register, and a language model suggests which sum each draws on, for the surveyor to confirm or split.
- Quotations, orders and invoices for each sum are attached as they arrive, from the contractor's submissions or your own records.
- For each sum, the ledger shows allowance, committed, spent and remaining, and the surveyor records a forecast outturn with a short reason.
- Sums heading over their allowance, or with a large unspent balance late in the job, are flagged.
- The ledger feeds the cost report and the final account, so the same figures appear in each.
How a sum should be expended and valued under the contract is a matter for your surveyor. The ledger records what has been instructed and spent, and the surveyor's view of where it is heading.
Provisional sums you can report on
The monthly cost report shows each sum's real position, not its tender allowance. Clients hear about pressure on the contamination allowance when the first instruction lands, not at completion. Unspent balances are visible, so the client can decide whether to release them. At the final account, the provisional sums section is already assembled, with every instruction and invoice attached.
It also helps the conversation with the design team. When an architect proposes a specification for the external lighting, the surveyor can say straight away how much of the sum is left, which is a better moment to have that discussion than after the order is placed.
Is this where your sums are?
- The cost report shows provisional sums at their original allowance.
- Instructions do not say which sum they draw on.
- Contractor quotations for provisional sum work reach you late.
- The first proper reconciliation happens at the final account.
- Clients have been surprised by an overspend inside a provisional sum.