The use of forms for pouring of concrete walls has been common in the construction industry for many years. In conventional construction, the concrete walls are produced by constructing form walls, pouring concrete into the space between the walls and, upon setting of the concrete, removing the form walls. Finishing materials may then be added to the concrete walls as required. As it is common, especially in colder climates, to insulate concrete walls, additional framing and insulation must be installed separately inside the walls.
In recent years specialized forms for concrete walls have been developed. The specialized forms are provided as two foam insulating blocks spaced apart the required distance by specialized metal or plastic bridging members. The insulating blocks are generally formed of expanded polystyrene and plastic or metal bridging members are provided to securely hold the insulating blocks in place when the concrete is poured in the hollow cavity and to tie the insulating blocks to the concrete. Once the concrete has been poured and set, the form walls are left in place to provide for the necessary insulation. If desired, finishing materials may be applied to the exterior surface of such walls. Examples of such concrete formwork assemblies are illustrated in U.S. Pat. Nos. 4,655,014, 4,706,429, 4,731,968, 4,884,382, 4,889,310, 5,390,459 and 5,809,728. While each of these designs utilizes the basic setup of the two foam blocks of polystyrene tied together with the metal or plastic bridging members, each of the designs has certain variations. A number of the designs are provided with interlocking means along the edges of the polystyrene blocks to interlock the blocks together when forming a complete concrete form. In addition, the attachment of the bridging members to the polystyrene blocks varies from design to design. In some of the designs the bridging members are provided with exterior plates which overlay the exterior wall of the polystyrene block. Other designs utilize structures which are held within the polystyrene block itself such that the bridging member is not exposed to the exterior of the wall.
Some of the designs of the specialized forms utilize plastic or metal bridging members having recesses or hooked structures, which provide for a means for attaching reinforcing bars or Rebar to the bridging members. This increases the strength of the poured concrete wall and also allows for using the forms for multistory buildings.
When the forms are used in a multistory building a means for attaching the header or rim joist for the floor structure must be provided. In the past this means of attachment of the header or rim joist has required that the insulation be removed in the area where the attachment is to be made. A spacer plate is then attached to the exterior wall, the spacer plate holding anchor bolts typically used for attachment of sill plates to a concrete wall. The anchor bolts are held on the spacer plate with suitable nuts and the shanks of the bolts extend inwardly into the hollow cavity. Once the concrete has been poured and the bolts have been secured within the concrete, the plate is removed and the header or rim joist is attached to the bolts by suitable nuts. This means of attachment is relatively labor-intensive, as it requires the installer to remove a portion of the insulation, attach the plate and the bolts and then once the concrete is poured and set, remove the plate from the forms. The anchor bolts are generally provided about every three or four feet around the periphery of the wall so there are quite a number of these operations required for a typical wall. When the header joist is to be attached to the wall, it is necessary to accurately locate the position of the bolts on the header or rim joist so that holes may be drilled in the header or rim joist. This can also be a tedious and labor-intensive operation especially for long headers or rim joists. There thus remains a need for an easier means of attaching headers and rim joists to concrete walls formed with insulated forms.