Architecture / June 13, 2018 / Oriane
The contractor is selected on the basis of competitive tendering on most building contracts. The price which the contractor quotes for the job is heavily influenced by both the amount and intensity of the competition expected. In an open tendering arrangement the level of the competition is at its most intense and contractors must submit highly competitive bids to have any chance of winning the contract. This usually secures a rock bottom price. With selective tendering a limited number of competent contractors are invited to tender for the job, this limited competition arrangement results in a keen price being obtained. In the case of a negotiated tender there is no explicit competition and the parties seek to agree a fair price for the work, implicit competition exists, however, as the employer can break off negotiations. If there is no competition the contractor can, in fact, name his price. The tendering arrangement is, therefore, one of the most cost significant decisions a client will make in the course of a building contract.
In general it can be said that larger buildings with simple, rectangular, regular floor plans and elevations will be less expensive per sq.m. of floor area than smaller, complex shaped, curved or angular buildings. Economies of scale apportion fixed overheads to a larger extent of productive space. Simple setting out and buildable solutions encourage greater plant use and generate higher productivity and less waste. Complex layouts and details are slower to assemble and may involve a number of trades with a consequent greater risk of mistakes and defects. The degree of compartmentation and repetition will also affect the overall cost of the work. New building work is considerably cheaper than work of a repairing nature or work in existing buildings. Single storey structures tend to be more costly than buildings up to three storeys high, beyond which point they become progressively more expensive.