This report provides an outline of good practice on the refurbishment and upgrading of existing overhead transmission line support foundations. Possible reasons for foundation deterioration are reviewed, which may result from such diverses causes as early-age concrete cracking to damage by frost forces. the critical nature of the inspection and testing strategy are considered, with attention focussed on the economics of the inspection/testing regime, the use of alternative strategies and the different levels of foundation inspection together with the actual inspection test methods.