One of the most common and cost-effective ways of saving energy in houses is to insulate the roof space, usually by laying insulation between the ceiling joists. But adding insulation increases the risk of condensation in the roof and can lead to damage to the contents of the loft, the insulation and possibly even the roof structure. This Good Repair Guide describes how to find out whether a pitched tiled roof is at risk from condensation and how to minimise it. 8 pages.