What are Insulated Concrete Forms (ICF)?

Insulated concrete forms are used in a home's wall system that combines insulation and concrete.  ICF's are formwork for concrete that stays in place as permanent building insulation for energy-efficient, cast-in-place, reinforced concrete walls, floors, and roofs. The forms are interlocking modular units that are dry-stacked (without mortar) and filled with concrete. The forms lock together somewhat like Lego bricks and serve to create a form for the structural walls or floors of a building.
 
Manufacturers commonly cite the following advantages compared to traditional building materials, especially in residential and light commercial construction.

• Minimal, if any, air leaks, which improves comfort and less heat loss compared with walls without an air barrier
• Thermal resistance (R-value) typically above R-17; this results in saving energy compared with uninsulated masonry 
• High sound absorption, which helps produce peace and quiet compared with framed walls
• Structural integrity for better resistance to forces of nature, compared with framed walls
  • Higher resale value due to longevity of materials
  • More insect resistant than wood frame construction
  • When the building is constructed on a concrete slab, the walls and floors form one continuous surface; this keeps out insects.
  • Concrete does not rot when it gets wet
• Reduces heating and cooling costs from 30%-70%
• Construction methods are easy to learn, and manufacturers often have training available
• ICF structures are much more comfortable, quiet, and energy-efficient than those built with traditional construction methods.
• Designing and Building with ICFs help your construction project attain Leadership in Energy and Environmental Design (LEED) Green Building status.
• Insulating Concrete Forms create a structural concrete wall (either monolithic or post and beam) that is up to 10 times stronger than wood framed structures.

Disadvantages include:

• Adding or moving doors, windows, or utilities is somewhat harder once the building is complete (requires concrete cutting tools).
• Cost - Depending on design, an average home will cost about five dollars per square foot more than a conventional wood built home. This usually amounts to about 5% of the cost of the home. For high-end wood homes this percentage decreases to about 2% or 3%. For high-end homes constructed of concrete the insulating concrete form solution is usually less expensive.
• During the first weeks immediately after construction, minor problems with interior humidity may be evident as the concrete cures. Dehumidification can be accomplished with small residential dehumidifiers or using the building's air conditioning system.
• Depending on the form material, concrete mix and pouring procedures, honeycombing may occur during the pour, where gaps are left in the concrete. This can be resolved with the use of a vibrator, using free draining form materials or self-consolidating concrete, though the latter option is much more expensive and not necessary.
• With polystyrene based forms, the exterior foam insulation provides easy access for groundwater and insects. To help prevent these problems, some manufacturers make insecticide-treated foam blocks and promote methods for waterproofing them.