Proving Design Life

9 Jan 2020

Building projects in the UK are specifying a design life of 60 years, but, British concrete standards give information to intended working lives of 50 or 100 years. British Precast Architectural and Structural have produced a helpful factsheet to resolve the discrepancy. 

The British Standard for Concrete, BS 8500, Part 1 Annex A provides guidance for the specifier for the nominal cover to reinforcement, concrete compressive strength class, maximum w/c ratio and minimum cement content for intended working lives of at least 50 years and at least 100 years. This guidance may be applied to precast walling and cladding elements. Many building projects in the UK still prefer to specify a design life of 60 years in line with previous versions of BS 7543, Guide to durability of buildings and building elements, products and components.
The slight disparity between the standard 50 years design life and a 60-year design life for walling, or precast cladding, elements may be dealt with by one of the following options.

•    Option I: Use 50 years (based on Table A.4 of BS 8500-1)
•    Option II: Use 100 years (based on Table A.5 of BS 8500-1)
•    Option III: Extrapolate to 60 years (Using a square root relationship & Table A.4, BS 8500-1)

Any of the three options for reinforcement cover determination may be used but the selection should be confirmed by the designer. The choice should be agreed on a project-by-project basis. All implications associated with units’ depth, geometry, weight and cost will need to be accounted for fully.

Full details of the three options can be found in our handy factsheet.

Download the full document here.