Keeping nature’s extremes at bay is no small task. Exterior walls must reject rain, wind, and cold in the winter and block excess heat in the summer. To do this, they must be well insulated and designed to be leak-free. A variety of siding systems have been created to accomplish these tasks.
Many different kinds of sidings are used on houses: clapboard and similar wood sidings; sheet sidings made of plywood, hardboard, and oriented-strand board (OSB); synthetics such as vinyl, aluminum, and steel; wood shingles; masonry veneers; and stucco.
In addition, exterior house walls are designed to hold up a house. With few exceptions, house walls are framed with wooden wall studs and then clad with siding. This provides the necessary strength, is relatively economical, and allows numerous options for appearance.
Though many older homes don’t have insulated walls, exterior walls of most homes built since 1970 are insulated. Insulation may be located in the cavities between walls studs or may be applied as rigid board panels over the top of—or instead of—sheathing.
But walls must be more than just efficient walls—they must contain windows for views and natural light and doors for access. Through these elements, they provide a connection with the world outside.
Housewrap, a relatively new material, significantly reduces heat loss caused by air infiltration through walls. Sold in 12-foot-wide rolls, the material is stretched over sheathing or walls studs and stapled or nailed in place. Because it is made from spun-bonded or woven polymer, it rejects water and wind but doesn’t trap indoor humidity in walls.
Building paper—a thick, black, asphalt-treated felt paper—provides a protective barrier between sheathing and sidings of wood, aluminum, vinyl, steel, or masonry veneer. It is applied horizontally across a wall, from the bottom up. Each 36- to 40-inch-wide layer overlaps the one below by about 2 inches.
Furring strips, a gridwork of 1 by 2s or 1 by 3s, provides a flat nailing base for some types of siding. Furring is required for nearly all vertical siding patterns.
