Generally, the drawings are produced by the design team. Many modern buildings are complex so that the production of the relevant drawings is itself a process which must be coordinated and planned.
Drawings provide a model of the design, concept and ideas behind a building. Formal drawings will be required as the basis of a planning application. Further detailed drawings will comprise the instructions for the contractor relating to the construction of the building.
There may be detailed drawings from specialist subcontractors and others. The process of coordination will be important. Upon completion as-built drawings will show how the building was completed and may form the basis for future maintenance and works.
Specifications and Bills of Quantities
Building agreements will commonly set out schedules setting out the quantities and dimensions in generic items. They will not generally be contract documents. However, they will be useful in providing information to others such as quantity surveyors and builders.
Specifications may set out the methods for construction, quality of finish, workmanship and materials to be employed. They may set out specific performance requirements.
Where the bills of quantity are used, the information will be generally contained in the bills. Many simpler works may be capable of definition by drawings and specifications alone.
Bills of quantities are prepared in accordance with published standards of measurement. The contracts will generally provide and warrant that the bills have been prepared in accordance with standard methods of measurement. In some cases,the quantity is an estimate The bills of quantities will usually serve to determine the valuation of variations directly or indirectly.
The purpose and effect of the bill of quantities will depend on whether it is specified as a contract document or not. When bills are incorporated, they define the quantity and quality of the work. However, the contract may require that the overall quality is of the type described in the contract. In this case the actual materials and quality of them set out may be subject to tests by the contract administrator.
Originally bills of quantities were used for tendering purposes. This is still their principal purpose in the context of engineering contracts. In more complex cases bills of quantity may be inadequate to serve all the conflicting purposes for which they are prepared.
Bills usually consist of preliminaries, preambles and particulars of measured work. They measure and provide a detailed quantification of the works. The preliminaries set out the definition and the scope of work. They will include particulars of the project, lists of drawings, descriptions of the site, scope of the work, details of documentation and management arrangements. Preambles were formerly a separate description of the materials and workmanship to be employed in the works. They are now less common.
Prime and Provisional Sums
A prime cost sum refers to works under the building contract that are to be carried out under the direction of the main contractor, by nominated subcontractors, suppliers or others. They will usually have been selected prior to the main contractor. As the main contractor does not control the pricing of this aspect of the work, a set amount is simply included in the bills to which the contractor may add a price for attendance including supervision, accommodation and plant,and also for profit.
Provisional sums are sums that are not yet finalised when the bills are prepared. They may be to allow for contingencies. The employer may not necessarily expend the sums concerned.
There may be contract instructions containing more information than the above documents. There may be schedules and further drawings setting out information. They may be necessary to execute the work. They must not be outside the scope of the contract or impose additional works on the contractor. If they do, a variation may be permitted by the architect/contract administrator.
The contractor will generally provide a program of work for approval. The program itself is not binding. Certain dates in it such as the specified date for completion may be binding in the sense that liability for liquidated damages will arise if it is not achieved.
Under standard form documents,the contract administrator may make directions in relation to discrepancies between the works. In some cases,this may entitle the contractor to additional time. If they constitute a variation then additional monies may fall due.
Traditionally the works were designed by the employer’s team. The architects, civil engineers and other design professionals were responsible for design. The contractor was responsible for construction. This is still the default / norm but is less common than before.
Design and built contracts are now well-established. In these contracts. responsibility for design and construction lies with the same party. In modern practice many systems provided by contractors involve an element of design. There was always often some element of discretion on the part of the contractor as to the detail of what is provided.
In practice, the design process is become increasingly complex. Various specialist designers may contribute parts of the overall works design. It may be necessary to coordinate and integrate various elements in various parts. In practice, many construction projects will involve the evolution of the design. They may move from an outline design, and be worked up to detailed design.
The obligations of design professionals are generally to use reasonable care and skill in the performance of the work. Generally, the courts measure the liability of professionals including design and construction of professionals by reference and standards of reasonable care and skill. They lean against unconditional warranties in design and build contracts.
The designer remains responsible for the design, notwithstanding that some elements may be completed by nominated subcontractors. The entirety of the circumstances must be examined. If the employer has placed no reliance on the contractor in relying on the design, there is no liability.
Nominated subcontractors may design their work. Under conventional building contracts, the contractor is likely to be responsible for defective design on the part of a nominated subcontractor. Subcontractor may enter a collateral agreement dealing with design issue.
The designer must exercise due care and skill, reasonable care and skill in selecting materials and building techniques. He must follow the standards of a reasonably competent designer who professes that skill.
Contractors & Design
The contractor’s responsibility for design was traditionally minimal. However, in practice, elements of design arise from the fact that the contractor must necessarily make numerous decisions at a low level in terms of implementations of the plans and specification.
Contractors may, in practice, be asked to offer solutions to particular problems that arise. They may be required to produce drawings for the architect’s approval. Contractors may have an implied obligation to notify the employer of defects in the design which have been discovered. Failure to do so may have contractual consequences.
Under modern design and build contracts, the contractor expressly undertakes design responsibility. A contractor on a design and build basis may take over the existing designs originated by the employer and take responsibility for them and for their further development and evolution.
Subcontractors & Design
Subcontractors often bring specialist design skills. The subcontractor will commonly enter a collateral warranty, as the contractor will not be responsible for the proprietary or design developments of what the subcontractor provides.
The subcontractor does not make an absolute warranty, but warrants instead, that what they do has been done with reasonable skill and care as far as designed elements concerned. As regards non-designed elements, the equivalent obligations for those undertaken by the principal contractor are undertaken.