Last edited 20 Sep 2021

Preliminaries in construction

Preliminaries (or 'prelims') may appear in tender documents, providing a description of a project that allows the contractor to assess costs which, whilst they do not form a part of any of the package of works required by the contract, are required by the method and circumstances of the works.

NBS suggest that 'the purpose of preliminaries is to describe the works as a whole, and to specify general conditions and requirements for their execution, including such things as subcontracting, approvals, testing and completion.' Preliminaries and work sections together describe what is required to complete the works required by the contract.

The costs attached to preliminaries may also be referred to as 'preliminaries' or 'prelims', or as 'site overheads', or general cost items or expenses. The Code of Estimating Practice published by the Chartered Institute of Building (CIOB) describes preliminaries as:

'...the cost of administering a project and providing general plant, site staff, facilities, and site based services and other items not included in the rates.'

Preliminaries in tender documents may include:

NB: Preliminaries should not be confused with 'preambles' which set out things such as tendering procedures, that will not affect the contractor's price. For more information, see Difference between preliminaries and preambles.

According to NRM1: Order of cost estimating and cost planning for capital building work, main contractor’s preliminaries are;

'...items which cannot be allocated to a specific element, sub-element or component. Main contractor’s preliminaries include the main contractor’s costs associated with management and staff, site establishment, temporary services, security, safety and environmental protection, control and protection, common user mechanical plant, common user temporary works, the maintenance of site records, completion and post-completion requirements, cleaning, fees and charges, sites services and insurances, bonds, guarantees and warranties. Main contractor’s preliminaries exclude costs associated with subcontractor’s preliminaries, which are to be included in the unit rates applied to building works.'

According to ‘Elemental Standard Form of Cost Analysis, Principles, Instructions, Elements and Definitions, 4th (NRM) Edition’ written by RICS in 2012 and published by BCIS, ‘the cost of preliminaries for the building being analysed should be stated and expressed as a percentage of the contract sum excluding preliminaries, contingencies and, where appropriate, contractor’s design fees.’

NRM1 defines ‘subcontractor’s preliminaries’ as;

‘…preliminaries that relate specifically to building work which is to be carried out by a subcontractor. Costs associated with subcontractor’s preliminaries are to be included in the unit rates applied to sub-elements and individual components.’

[edit] Related articles on Designing Buildings Wiki


Comment 1: All of these “preliminaries” are quantifiable, so why should they be expressed as a percentage of the overall costs? This seems a lazy and sloppy way to calculate them, and not particularly accurate, and a licence to print money for the contractor.

Comment 2: In response to comment above: It's true that prelims are quantifiable after the event (eg. at final account) but the best a Contractor can do when tendering on a fixed price basis is make an appropriate allowance to cover the prelim costs it expects to incur. In doing so, it is left with the risk should it incur greater prelim expense during the execution of the works (save for instances like variations, where those costs arose due to factors outside of the Contractor's control). The approach proposed by the OP above would leave all the risk with the Employer and a Contractor could easily substantiate additional prelim costs if it were so inclined.

Designing Buildings Anywhere

Get the Firefox add-on to access 20,000 definitions direct from any website

Find out more Accept cookies and
don't show me this again