Edinburgh Napier University

  Volumetric modules are often employed as an efficient and effective means of
constructing highly serviced areas in buildings such as bathroom, kitchens and
structures to house mechanical plant and equipment. Recent developments in
structurally integrated volumetric pod concepts have seen a shift towards small format
modules with the ability to be configured to provide alternative architectural solutions
as part of a product family architecture. However, without careful consideration of
the procurement strategy for such products, cost variation can arise from additional
labour and materials required to make good and mend the results of design and
construction process decisions that may not have been undertaken in concurrence.
Using the unique case of a city centre project constructed using volumetric bathroom
pods and a series of pre-engineered component kits (supplied by the pod
manufacturer) an unusual financial comparison of two modern methods of bathroom
construction is presented. The data emanating from the unit of study includes
manufacturers production cost data and site based sub-contractors labour and material
costs and considers the context of the construction in terms of new-build and building
refurbishment. This is then used to provide an economic comparison of the use of
volumetric pods and simpler pre-engineered component kits. Significant cost
variation has occurred and the benefits of using off-site manufactured bathroom pods
have been eroded due to specific procurement decisions and the complexity of the
interface procedure with other trades and on-site constructed building elements.
Using this method of comparison, those considering implementing modern methods
of construction for bathroom and washroom facilities are provided with procurement
strategy guidance in obtaining improved control over labour and material costs
through using the modern methods of construction presented.
Keywords: Buildability, innovation, prefabrication, standardisation, cost.