The product area covered in this book is that of the Standard Industrial Classification 19681 for construction as follows: Erecting and repairing buildings of all types. constructing and repairing roads and bridges: erecting steel and reinforced concrete structures; other civil engineering work such as laying sewers, gas or water mains, and electricity cables, erecting overhead lines and line supports and aerial masts, extracting coal from opencast workings, etc. The building and civil engineering establishments of government departments, local authorities and New Town Corporations and Commissions are included. On-site industrialised building is also included. Establishments specialising in demolition work or in sections of construction work such as asphalting, electrical wiring, flooring, glazing, installing heating and ventilation apparatus, painting, plastering, plumbing, roofing. The hiring of contractors’ plant and scaffolding is included. However for purposes of this book the construction industry is defined somewhat wider to cover all those parties involved in the construction process including the professions, the contracting industry (as above) and to some extent the suppliers of inputs who jointly respond to the needs of the clients of the industry.