Architecture / June 6, 2018 / .
This is where the contractor provides the design and construction under one contract. Turnkey projects and many public private partnership developments are examples of this approach. Design and build offers the client competitively priced projects completed within rapid time frames by enabling the contractor to value manage the employers requirements and overlap design and construction operations. It is not successful where the employers requirements are poorly defined and the approach tends to produce functional architecture in terms of appearance.
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.
Speedy completion is often required on commercial developments. The pressure to achieve early completion intensifies when financing and interest costs associated with acquiring the site begin to mount. Clients will seek the early appointment of a contractor in these situations to enable a fast start up on site and will favour fast track design approaches where the design is developed in parallel with site construction operations. Such approaches risk allowing insufficient time to identify or consider beneficial design options, and may, on occasion, lead to abortive working and losing time. Speedy construction on site often requires accelerated working and shift or overtime payments, more intense management presence, and the use of dependable subcontractors and suppliers, all of which add to the cost of the project. Fast track approaches rule out cost certainty and the client will become aware of the eventual cost only at an advanced stage of the project.
Local contractors are usually at an advantage when competing for work. Contractors who have the capacity to construct work from within their own organisation should, in theory at least, be more competitive than those who sub-contract large proportions of the work. Current site management practice however tends to favour the widespread use of subcontractors. Nevertheless, the ability to attract labour and to source materials in the locality is an important factor in ensuring that unnecessary travelling and transport costs are not incurred in carrying out the work. Seeley notes that contractors will have to consider whether management, labour and plant resource requirements can be met from within the contractors own organisation or whether it will be necessary to recruit specifically for the project. The contractor will also have to consider what demands the proposed project would put on own plant, scaffolding and equipment.