The term stress-skin is used to describe a three-layered insulating panel, which has specific structural qualities for strength as well as providing insulation. They are also referred to as SIPs -structural insulated panels. A layer of foam insulation is sandwiched between an exterior sheathing of OSB (oriented strand board) and an interior of gypsum wallboard (sheetrock). Stress-skin panels are a simple and efficient method of enclosing and insulating a timber frame. They are quick to install onto a timber frame because the interior finish, insulation and exterior sheathing are combined and installed in one operation. Stress-skin panels wrap a frame in an uninterrupted envelope of insulation.