Wall form, texture, and use influence safety concerns. Where there are walls undulate or project into small wings, dark niches are created for people to hide. The use of these spaces for hiding can be reduced by planting hedges, or providing recessed exterior lighting or windows.
Walls in graffitti prone areas should be made of a durable material that can handle repeated cleaning.
Screen walls of metal or decorative concrete block are often used to provide separation without compromising ventilation. However they can become informal ladders allowing unauthorized access to the roof. This can be prevented by making sure that the screen wall provides no footholds and that the top three or four feet near the roof is smooth and unclimbable.
Walls near recreation areas are often defaced by spray paint by youths making markings for games such as handball and street hockey. Provide markings and game lines before hand so that children will not be tempted to make their own.