The building envelope of a house consists of its roof, sub floor, exterior doors, windows and of course the exterior walls. A tight building envelope is preferable in cooler climates. The term “building envelope” describes the total wall, roof, floor and fenestration aspects of a building system. The critical nature of the built enclosure requires the utmost attention that its design sheds water. Performance over time requires understanding of various trades and proper installation, and an understanding of sustainable construction practices.