They also lay standards for drains, ventilation, protection against the ingress of water and protection against contamination including methane and radon gas. As part of the process of developing the drawings to meet the requirements of the Approved Documents, there is sometimes the need for involvement from a range of other consultants to bring together your project including structural engineers, energy assessors, drainage consultants so that you can provide your contractor with a comprehensive package of information that has been approved through the building control process.