Conventional concrete has been an integral part of nearly all residential construction in the United States for centuries. Poured-in-place concrete or concrete masonry unit construction is frequently used to construct the foundations and basements of all types of single-family houses. Poured-in-place concrete is also commonly used to construct driveways, walks, and patios for the U.S. residential market. A number of other cement-based products are routinely used in single-family construction, including concrete roof tiles and cement-based shingles.

The first recorded house using above-grade concrete walls in the United States was built in 1844 in Milton, Wisconsin, by tradesman and innkeeper William Goodrich. He sought protection from arson and attacks by Native Americans. The house, with its massive load-bearing walls and six-sided three-story tower, remains intact today and serves as a museum.

The introduction of two user-friendly concrete construction systems to the United States has provided builders of single-family homes with more choices for the construction of above-grade walls. For decades, home builders throughout Europe have built extensively using the two technologies-insulating concrete form systems and autoclaved aerated concrete-but the systems were not widely available in the United States until after 1990. These concrete systems are now attracting U.S. interest because they provide alternatives to timber construction that combine properties of fire resistance, superior thermal insulation and sound insulation, and are easy to construct.

Insulating Concrete Forms

Insulating concrete forms (ICF) are polystyrene forms shaped as blocks or panels. Builders arrange these forms to create walls, insert reinforcing steel in the form voids, and fill the voids with ready mix concrete. Unlike traditional forms that are removed after the concrete sets, the foam forms are left in place to become a permanent part of the house, providing built-in insulation. The thermal performance of the ICF wall assemblies can be equal to R-40 or R-50 stud wall construction. ICF walls accept virtually any finish, including gypsum wallboard on the interior and wood or vinyl siding, brick, or stucco finishes on the exterior. U.S. builders have used ICF systems to build homes in a range of architectural styles throughout the country.

Aerated Concrete

Autoclaved aerated concrete (AAC) is a lightweight concrete that has been popular worldwide for commercial, industrial, and residential construction for years, but became available in the United States recently. Like conventional concrete, AAC consists of cement, lime, fly ash, water, and aggregates. To make AAC, the manufacturer also adds aluminum powder to the mix, molds the concrete into shapes, and bakes it in an autoclave, which steam-cures the concrete under pressure. The process produces a material that weighs only one-fifth as much as a conventional concrete block of the same size. The concrete's light weight makes it easier to lay up during construction, and its aerated structure gives it better insulation and sound absorption values than conventional concrete.

Concrete Masonry

Concrete masonry units remain a popular choice in concrete home construction. New types of concrete block, advances in rigid foam insulation, and advances in construction methods have combined to provide concrete block building systems that are cost effective and that out-perform yesterday's systems. Interior insulated block, exterior insulated block, and in-block insulation help make these walls high-performance systems. Lightweight concrete blocks can speed installation. Because they are up to 25 percent lighter in weight, a mason can lay many more blocks in a day.

Benefits for Homes

Fire-resistance and strength are characteristics of concrete that continue to make it attractive to the residential construction market today. Since concrete is incombustible, it provides superior fire protection. This fire resistance is recognized by insurance companies, who commonly offer lower rates to owners of concrete homes. During major fires in southern California in the early 1990s, for example, concrete homes were left standing while complete subdivisions burned around them. Concrete's natural strength and stability have also proven valuable in regions of the country subject to wind-producing storms such as tornadoes and hurricanes. Concrete homes in southern Florida withstood the effects of major storms in the early 1990s, sustaining less damage and posing less of a threat to their occupants' safety than their wood- and steel-frame counterparts. Concrete's resistance to rot, rust, and infestation by insects has contributed to its popularity for residential construction in hot, humid states such as Florida.

A number of creative, innovative products are giving concrete wider visibility in American homes. Colored and textured floors-either precast, cast-in-place, or in the form of concrete floor tiles-have gained popularity, as have fireplaces and other interior surfaces that are made from concrete but imitate the appearance of stone. Concrete is even showing up in kitchens and bathrooms: precast concrete countertops, sinks, and tubs are available to aficionados of the material.

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