Insulating concrete forms (ICFs) are rigid plastic foam forms that hold concrete in place during curing and remain in place afterwards to serve as thermal insulation for concrete walls. The foam sections are lightweight and result in energy-efficient, durable construction. ICFs can be used to form various structural configurations, such as a standard wall, post and beam, or grid. They provide backing for interior and exterior finishes. Typical insulation values range from R-17 to R-26, depending on thickness, compared to between R-13 and R-19 for most wood-framed walls. ICF walls are designed as reinforced concrete, having high wind and seismic resistance.