The aim of this three-part Good Building Guide is to give the best advice on achieving airtightness in new buildings. It is based on data obtained from laboratory testing and observations made while undertaking air leakage audits in buildings. This third part gives practical guidance on techniques for achieving airtightness in windows and doors, sealing methods and materials. 6 pages. Part 1 (available separately) describes the common air leakage paths and sets out the principles to follow when developing energy efficient construction details and Part 2 (available separately) provides practical guidance on achieving airtightness in floors, walls and roofs. Part 3