A. Timber is a natural product that reacts to changes in temperature and climate. Rustic sheds are made from freshly sawn Irish timber and in the normal drying process (especially in very warm weather) cracks can occur. These can be filled with a suitable coloured silicone to ensure shed remains waterproof. Small hairline shakes (commonly mistaken as cracks) can develop in Pressure Treated Shiplap and Barrel Board timber over time but in no way affects the life span of the Shed.