Insulated concrete forms (ICFs) are one of the most efficient and cost-effective methods of home construction in use today. The basic technology has been in existence for several decades although modern materials and equipment have greatly increased the strength and flexibility of the technique. There are a few basic points to understand when looking at ICF for home construction.
An ICF is a formwork that is made from expanded polystyrene (EPS) or another material like polyurethane. Blocks of the material are stacked to create the edges of the form with an open space in the center. Metal reinforcing bars or other supports are often placed at regular intervals between the blocks. The final step is the careful pouring of concrete into the form. This pouring is usually done slowly in stages. The form becomes part of the permanent structure once the concrete has cured. The result is a wall that has an efficient layer of interior and exterior insulation because of the ICF as well as a core of reinforced concrete for durability and added protection.
The walls of a home that has been constructed with ICFs are considered high mass because of the concrete. This makes the home incredibly strong when compared to most other residential construction methods. The concrete is resistant to fire and water damage. The solid concrete also makes it difficult or impossible for pests, rot or age to degrade the structure of the walls. Homes that are built with ICFs are much more resilient during hurricanes and tornadoes although the EPS foam might sustain some damage. The use of rebar throughout the concrete gives the walls of a home additional flexural strength so that cracks and other types of damage are less likely.
Walls that are made from poured concrete and encased in an ICF have superior insulating properties when compared to most other types of home construction. The ICF means that more of the wall is insulated than with fiberglass or other installed types of insulation. The result is that the ICF wall reduces the amount of noise coming into the home by more than two-thirds when compared to other traditional types of walls. These same insulating properties also reduce airflow through the wall by two-thirds. The thermal mass is higher than most other residential building materials so that the home will not shed heat or cool air as quickly as a building with standard fiberglass insulation.
There are some environmental benefits from ICF construction. The amount of waste that is generated on a construction site while a home is being built is reduced dramatically when using an ICF system. The thermal mass of the walls makes heating and cooling systems in the home more efficient. This reduces the energy that is needed each season. New environmentally friendly materials are being explored for use in the concrete forms including soy-based biopolymers that require less energy to produce. This makes an ICF system one of the more environmentally responsible choices for home construction.