A type of tar paper or more modern membranes in newer properties or those where the roof has been re-covered, used underneath tiles or slates in a roof. It can help to provide extra rainwater protection and prevents wind lift. Liners should continue below the lowest tiles on the roof and into the gutters to channel any rainwater that has found its way beneath the tiles into the rainwater disposal system. Commonly the liner degrades in the sun and retracts at the eaves, meaning rainwater cannot reach the gutters. This can cause decay to the roofgin timbers and any timber joinery. Roofs can often be relined at the eaves or eaves guards can be installed at the lower edge of the roofline.