The use of stud walls for constructing houses and other buildings has been around for over 200 years. It's basically a structure with support boards spaced evenly down the length of a wall with the exterior of the wall covering these supports with a solid surface. The solid surface these days is gypsum board if it's an interior wall or the exterior sheathing and siding if it's an outside wall. Even though stud walls have been around for a long time, there are variations between different types.
Interior stud walls are generally made using two-by-four studs as the structural lumber. In most cases interior, stud walls are hollow; electrical wires, plumbing pipes or other mechanical runs are often routed through interior wall cores. In special cases, interior walls are insulated. Insulation is added most often as a soundproofing material to keep noises from passing through the walls. Occasionally, speciality rooms to be kept warmer or cooler than adjacent rooms have insulated stud walls.
Local building codes in most parts of the United States have been revised to require exterior stud walls in remodel projects and new construction to be made from two-by-six lumber. Some builders opt to use two-by-eight boards to make their studs. The extra thickness of the walls provides room for additional insulation material to be installed and with today's energy prices for heating and cooling, the extra cost of materials and insulation materials is offset in very little time.
Architects frequently add knee-walls, half walls and partition walls to homes strictly for decorative purposes. Commonly, these are nonstructural but built to the same standards as structural interior walls. Depending on the configuration and use, the typical 16-inch spacing of the studs in these decorative walls may be abandoned for wider or narrower studs.
Metal Stud Walls
For a period in the 1990s when lumber prices were skyrocketing, some builders switched to using galvanised steel studs instead of wood in stud walls. Steel walls proved to be no better, worse or substantially stronger than wooden walls, but builders had to learn and adapt to using the new material. Steel price increases removed the price advantage and now, unless there are special, industrial applications to consider, most builders have abandoned steel stud walls.