ABSTRACT
Quantities in this volume are given in SI units which have been adopted by the construction industry in the United Kingdom. Twenty-five other countries (not including the USA or Canada) have also adopted the SI system although several of them retain the old metric system as an alternative. There are six SI basic units. Other units derived from these basic units are rationally related to them and to each other. The international adoption of the SI will remove the necessity for conversions between national systems. The introduction of metric units gives an opportunity for the adoption of modular sizes.
