This Good Building Guide gives practical help in the different methods of building insulation into each part of the house (eg ground floors, external walls, windows/doors and roofs). Deficiencies in detailing that allow air leakage and thermal bridging will cause condensation, mould growth and excessive energy use in the finished house. Following the advice in this Good Building Guide will result in a well-insulated house that is warmer to live in, cheaper to run and better for the environment. 16 pages in total. N.B. This good practice guide is about installing insulation in new-build homes, and is not about retrofitting insulation in existing homes (though the advice and illustrations on insulating a room-in-the-roof could be useful if creating one in an existing home, it is only one page of the document). Part 1 covers general principles of preventing thermal bridging and air leakage, and gives detailed advice applicable to insulating ground floors, pitched roofs and rooms-in-the-roof. 8 pages. Part 2 covers the insulation of external cavity walls, windows and doors, and lists references for further reading. 8 pages.