For more information for small sites see Welfare facilities What you need to know as a busy builder.
Information on how many toilets should a workplace have is available online.
If using portable chemical toilets you need 1 for every 7 people working a 40 hour week.
There should be an area for securely storing clothing and for drying wet items.
There should be a room where workers can eat and drink.
People working at a demolition site must have access to at least the normal construction range of facilities including: toilets; large wash basins; running hot (warm) and cold washing water; washing consumables; a clean rest room with lights, heating and seating; drinking water, means to heat water/food; and an area for storing and drying work clothes. In addition if the work is dirty - and demolition work frequently is - then showers must be provided.