Obviously, each roof is different and taken on its own merits. Whether itβs a slate, tile or fat roof there is usually something that can be done to repair and prolong the roofs lifespan. By replacing broken or damaged slate/tile or patching and sealing a flat roof you can achieve this. The problem will be the condition of the battens or the flat roofing boards, and whether or not they can still take the weight of the roofing products sitting on them. If they are rotten and in a dangerous state then you will be looking at a full re-roof unfortunately