5/3/2023 0 Comments Icf blocksThis simplifies ordering and the overall build. Concrete has an R-value of 0.06 per inch-increasing the core size adds to the thermal mass of the wall but does very little to improve the overall R-value of the wall assembly.Ĭonstructability – The best scenario in any build is to use the same size concrete core block from the footings to the roof. ICFs have proven experience surviving tornadoes, floods, and wildfires.Įnergy Efficiency – The thermal rating of an ICF wall assembly is provided mainly by the double EPS insulation layers. Resiliency – A 6-inch ICF reinforced concrete core has passed testing for high winds, flying debris, and 4-hour fire resistance. High Wind Areas – A 6-inch ICF wall assembly has been tested for wind speeds over 200 mph and for construction of FEMA approved safe rooms. 4-inch concrete cores may not be applicable moving up to 6 or 8 inches. Seismic – In high seismic zones larger core sizes may be required to add double layers of rebar. There are a few additional design attributes that may influence the core size and the reinforcement layout. 6-inch may be multiple stories up to 14 feet high between lateral supports.4-inch limited to one-story, 10 foot high.General rule for ICF concrete core sizes on above grade residential walls: Design the transition change in wall thickness at an appropriate spot. Here, an 8-inch concrete core is required, but the remainder of the home could use a 6-inch concrete core. Since rebar is cheaper than concrete, look to selecting an acceptable thinner concrete core.įor homes with a great room or large foyer, these above-grade walls may be two stories high between lateral supports. In these regions an 8-inch concrete core is required.Īs the design variables increase, the rebar layout increases, and as the concrete core size increases, the rebar layout decreases. In some areas, local building codes state that foundation walls must be a minimum of 8 inches of concrete. In most areas a 6-inch ICF reinforced foundation wall meets the IRC requirements. For foundation walls that exceed the 10-foot height between lateral supports, project specific engineering would be required or check with your ICF manufacturer for an engineered design. For above grade walls, similarly the distance between floor connection or the floor and roof connection is the lateral support distance. The distance between these support connections, or unsupported wall is what is used in the design tables. In the IRC code tables this distance is identified as the Unsupported Wall Height. Lateral support is the measurement between support connections of the ICF wall. ICF manufacturers may have engineering tables for walls higher than 10 feet. The IRC (International Residential Code) tables list walls up to 10 feet high between lateral supports. Different design variables but these are easily met by ICF reinforced concrete walls. For above grade, typically a 4- or 6-inch core size is used. Above grade walls may be built on slabs, grade beams, or ICF foundations. A 4-inch ICF concrete core cannot be used for below grade walls.Ībove grade walls are any walls that do not retain earth. For residential construction, a 6- or 8-inch core size is typically used. A crawl space or stem wall is designed as a below grade wall. The concrete core size engineering follows three main design attributes-below grade walls, above grade walls, and lateral support.īelow grade walls are foundation walls that retain earth and supports a structure of either wood framing or concrete. This provides a huge savings in not only concrete costs, but in installation labor, especially for foundation walls. The structural advantage of reinforced concrete design allows for thinner walls than those required for regular poured concrete or concrete block walls. The range allows for different applications and engineering design criteria. A majority of ICF companies provide forms with concrete core sizes at 4, 6, 8, 10, and 12 inches.
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