Architecture / June 25, 2018 / .
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.
This is where the contractor works alongside or within the design team providing a construction management service. The management contractor does not undertake either the design or the direct construction work. The physical construction is carried out by specialist subcontractors, package contractors. There are two main forms of this approach: Management Contracting where the contractor employs the subcontractors and Construction Management where the subcontractors are employed directly by the client and the project is managed by the construction manager - there is no actual main contractor. Management procurement routes are associated with fast moving, complex construction projects. The early appointment of manager within the design team allows the design and construction operations to be fast-tracked while also ensuring that the required quality standards are delivered. These projects, however, tend to be expensive. Figure 1 sets out a summary of the advantages and disadvantage of various procurement approaches which may be of use in meeting project objectives.
The notion of quality is multidimensional and includes aspects which may be appraised subjectively. The Latham Report identified a number of quality aspects which clients may seek in a satisfactory construction project: pleasing to look at; free from defects on completion; fit for the purpose; supported by worthwhile guarantees; satisfactory durability and customer delight. Several of these aspects are inherent in the design of the project, while others relate to how successfully the contractor constructs that design on site. The designers will aim to produce an effective and attractive spatial and structural solution to the clients brief. This should provide sufficient, well planned accommodation, using appropriate materials, components, equipment, fittings and furnishings to enable the building to perform effectively and efficiently. Ideally it should generate a sense of delight amongst it users and the public at large.
The geometry of a building has a major impact on costs. Building morphology is concerned with the size, shape and complexity of the building. This section provides a very brief outline of the principle morphological factors which influence the cost of building work. The reader is referred to the numerous publications which examine this topic in greater detail. The main design factors which impact on cost are: plan shape, size of building, wall to floor ratio degree of circulation space, storey heights total height of the building grouping of buildings.