2.3.4 Building and demolition sites Building and demolition sites are dangerous places. The site contractor is responsible for your safety and you should make sure that you are always accompanied by a site representative and follow any safety instructions you are given. Normally the wearing of a hardhat is mandatory. 2.3.5 Visits to roof voids Visits to roof voids always carry a risk of falling through a lath-and-plaster or plasterboard ceiling. These risks are multiplied in older buildings, where rotor woodworm attack may have weakened the timbers. This is a dangerous and expensive mistake to make and can be avoided by moving steadily and methodically and only ever walking on sound joists. A good torch is essential for checking the position and soundness of the joists, and one hand should always be kept free for holding onto the roof trusses to maintain balance. In some roofs, joists maybe in such a poor state that the visit should be abandoned or the search confined to sound areas of the roof. Before entering a confined space like this, always ensure you have a safe means of exit in case of emergency. CHAPTER 2 HEALTH AND SAFETY IN BAT WORK 26 There are several other potential hazards.