Undefined provisional sum
A provisional sum is an allowance (or best guess), usually estimated by a cost consultant, that is inserted into tender documents for a specific element of the works that is not yet defined in enough detail for tenderers to accurately price.
A provisional sum can be categorised as ‘defined’ or ‘undefined’.
Undefined provisional sums are less well described as they refer to work which is not completely designed. As such, the contractor cannot be expected to make allowance for them in their programming, planning and pricing preliminaries. This means the contractor may be entitled to an extension of time and/or additional payments when the actual works are undertaken.
An example of an undefined provisional sum might be work required below an existing structure, where the ground conditions, and so the extent of work required, cannot be determined until the structure is demolished and the ground opened up.
With undefined provisional sums, the client typically bears the price and scheduling risks.
Defined provisional sums are those which have been described in sufficient detail that the contractor is expected to have made allowance for them in their programming, planning and pricing preliminaries.
[edit] Related articles on Designing Buildings
Featured articles and news
Reasons for using MVHR systems
6 reasons for a whole-house approach to ventilation.
Supplementary Planning Documents, a reminder
As used by the City of London to introduce a Retrofit first policy.
The what, how, why and when of deposit return schemes
Circular economy steps for plastic bottles and cans in England and Northern Ireland draws.
Join forces and share Building Safety knowledge in 2025
Why and how to contribute to the Building Safety Wiki.
Reporting on Payment Practices and Performance Regs
Approved amendment coming into effect 1 March 2025.
A new CIOB TIS on discharging CDM 2015 duties
Practical steps that can be undertaken in the Management of Contractors to discharge the relevant CDM 2015 duties.
Planning for homes by transport hubs
Next steps for infrastructure following the updated NPPF.
Access, history and Ty unnos.
The world’s first publicly funded civic park.
Exploring permitted development rights for change of use
Discussing lesser known classes M, N, P, PA and L.
CIOB Art of Building 2024 judges choice winner
Once Upon a Pass by Liam Man.
CIOB Art of Building 2024 public choice winner
Fresco School by Roman Robroek.
HE expands finance alliance to boost SME house building
Project follows on from Habiko public-private place making pension partnership for affordable housing delivery.
Licensing construction; looking back to look forward
Voluntary to required contractors (licensing) schemes.
A contractor discusses the Building Safety Act
A brief to the point look at changes that have occurred.
How orchards can influence planning and development.