Following the introduction and executive summary, this report covers: alternative approaches to predicting service lives for components; features of a factorial approach to service life prediction; analysis of critical factors affecting service life; experience of factoring systems and recommendations on number of factors; worked examples for pressed steel lintels, softwood windows, and fibre-based cement slates; summary of findings, and conclusions. 37 pages. This publication can now only be supplied on-demand as a photocopy .