![]() ![]() Unless a self-consolidating concrete mix is used, concrete should be vibrated after pouring to remove trapped air as air pockets can lead to thermal bridging and weaken the cement ( ICF Builder 2012).įigure 7. A pumper is used to place the concrete into the foam form walls (Source: National Research Council Canada).ĭepending on the specific system, the walls may allow attachment of exterior and interior wall coverings directly to the wall with little or no modifications to the wall. A good item to have on hand when the concrete arrives is a blowout repair kit. For earthquake-prone areas, reinforcement should be designed per seismic design requirements. Reinforcement in both directions maintains the wall strength. Form failures are rare when the manufacturer’s recommendations are followed. Even with the bracing, the forms need to be filled at an appropriate rate based on the ICF manufacturer’s recommendations to prevent misalignment and blowouts. Once the forms are in place and braced, and required reinforcement is installed, concrete is pumped into the forms (Figure 7). Figure 6. Window and door rough openings in the ICF wall are surrounded with pressure-treated wood (Source: Oak Ridge National Laboratory). Special molded corners provide continuous insulation layer at the corners to improve structural strength and minimize thermal bridging (Source: Portland Cement Association). Figure 5. The blocks stack to form walls. Ledgers can be mounted to the blocks for attaching floor framing. Lumber blocking is also needed where bearing pockets are required for floor or roof supports. Window and door openings must be framed with lumber (Figure 6). Most manufacturers make specifically molded corner blocks that provide a continuous layer of foam around the corner to reduce thermal bridging there (Figure 5). ICF systems are installed in a manner similar to masonry, starting at the corners and placing a layer at a time to build up the wall. Figure 4. Different types of ICF blocks (Source: Oak Ridge National Laboratory). Figure 3. Three common ICF wall systems: the flat wall, the waffle wall, and the post-and-beam wall (Source: Oak Ridge National Laboratory). The post and beam ICF wall system has vertical and/or horizontal concrete members spaced farther than 12 inches on center. The screen-grid ICF wall system is similar to a waffle-grid ICF wall system without concrete webs in between the vertical and horizontal members. The waffle-grid ICF wall system is a concrete wall composed of closely spaced vertical (maximum 12 inches on center) and horizontal (maximum 16 inches on center) concrete members with concrete webs between the members. A flat ICF wall system is a solid concrete wall of uniform thickness with sheets of insulation forming the interior and exterior surfaces of the system. Figure 1. ICFs provide continuous wall insulation from the roof to footing with very little thermal bridging the ICFs in this home in Las Vegas provide R-40 wall insulation (Source: Department of Energy).įigure 2. The ICF consists of wall forms made of rigid foam blocks or panels that are held in place with plastic or metal spacers and reinforced with metal rebar (Source: National Research Council Canada).Ĭommon types of ICF walls are shown in Figures 3 and 4. Some ICF walls consist of two layers of concrete sandwiching a central layer of foam. A few products are made with recycled foam or wood. Some ICF products use extruded polystyrene (XPS) foam, which is stronger but more costly. ![]() The foam is typically expanded polystyrene (EPS). Some ICFs come with plastic nailing strips embedded in their exterior surfaces. Steel rebar is added to the cavities for additional strength (Figure 2). The blocks are stacked like bricks to create the wall forms for the concrete. The ties hold the foam panels 6 or 8 inches apart during the pour and remain in place afterward. Foam blocks are typically comprised of two 2-inch-thick, 16 by 48-inch rectangles of foam that are connected by plastic, metal, or foam ties. The foam forms stay in place, providing permanent insulating foam layers on the interior and exterior of the wall. ICFs are typically made of pre-molded blocks or panels of rigid foam, which are assembled on site to create wall forms into which concrete is poured (Figure 1). ![]() ICF walls have almost no thermal bridging in the wall itself and, with proper design details, thermal bridging can be almost eliminated at the rim joist as well ( Petrie et al. Studies comparing ICFs with stick-frame construction have shown that in otherwise identical homes, the ICF houses had a 9% better whole-wall R-value and were 10% more airtight ( Christian 1996). Insulated concrete form (ICF) construction combines concrete and rigid foam for walls that are thick, sturdy, and continuously insulated. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |