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This invention relates to a structural hanger for attaching a structural member to a supporting wall and, more particularly, to a structural hanger for attaching a ledger or joist for a floor or roof to a concrete wall, such as those built using stay-in-place concrete forms.
Building construction typically includes connections between various structures such as walls, floors and roofs. In some building designs, the roof is supported below the top of exterior walls, creating a parapet wall at the top. Since the roof is not supported by direct attachment to the walls, this design requires some form of intermediate support between the walls and roof to support the roof structure. Similarly, a raised floor or second story floor of a house may require a supporting structure that attaches the floor to the walls. This supporting structure is typically provided by a number joists that are attached to ledgers attached to the supporting walls with ledger hangers. Alternatively, the joists may be attached to the walls without ledgers using joist hangers.
Ledgers and joists are typically elongate wood or steel members. In grouted masonry or concrete wall systems, anchor bolts are embedded into the walls and provide hangers attaching ledgers to the walls. In securing a ledger to a wall structure using anchor bolts, modern building codes require all bolts to be grouted in place with at least one inch of grout between the bolt and the concrete form. This requires suspension of the anchor bolts in their larger containing holes until the grout or concrete secures them in this position.
Due to the difficulty of suspending anchor bolts inside of larger openings, use of an embedded steel plate structural hanger has gained popular usage in poured concrete walls erected using stay-in-place forms, particularly in the category of insulated concrete forms (ICFs). These hangers are typically a rigid steel plate having an embedded portion and an exposed portion that exits the wall with a right-angle bend. These hangers are easily installed by slipping the hanger into position through a slit cut into the wall form prior to filling the form with concrete. Once the concrete is poured and sufficiently cured, the hanger becomes securely fastened to the supporting wall. If the exposed portion extends out of the wall perpendicularly, a joist can be attached directly to the hanger, thus eliminating the ledger (A disadvantage of this technique is that placement of the embedded joist hangers must be very precise).
The steel plate structural hanger provides a simple and effective means for attaching steel members (ledgers or joists) to walls using self-tapping screws. However, attachment of wood members presents additional difficulties. Common implementations use an additional steel outer plate to sandwich the wood member between the outer plate and the embedded portion of the hanger. The wood member is then secured to this double plate arrangement using numerous self-tapping screws running through the outer plate, the wood member and into the hanger. This method is more complicated than that used with steel ledgers and requires great care to prevent overheating and subsequent failure of the self-tapping screws when they are passed through the wood member.
The system and method of the present invention avoids the disadvantages of the prior art systems and methods. It provides an easier, less expensive and more reliable means of attaching structural members to poured concrete walls.
The present invention is a structural hanger for attaching a structural member to a poured concrete supporting wall. It is simple and relatively inexpensive to manufacture, simple to use and performs its function with great reliability. The structural hanger contains one or more through-holes that provide a means for attaching a wood member to the structural hanger using carriage bolts or the like.
FIG. 1 is a perspective view of an embodiment of the structural hanger of the current invention that is configured to be embedded into a concrete wall and to provide a surface for attaching a ledger to the hanger.
FIG. 2 is a side elevation view of the structural hanger shown embedded in a concrete wall and connecting a wood ledger to the wall.
FIG. 3 is a side elevation view of the structural hanger shown embedded in a concrete wall and connecting a wood joist to the wall.
Referring to FIG. 1, the structural hanger of the preferred embodiment comprises a rigid steel plate having an embedded portion 1 containing embedment holes 2 and a ledger attachment portion 3 having square holes 4. The hanger is installed by slipping its embedded portion into a vertical slit cut into a stay-in-place concrete wall form. The form is then filled with concrete. The embedment holes 2 in the embedded portion provide a mechanical attachment of the hanger into the concrete.
After the concrete has sufficiently cured, the hanger is used to support a either a steel ledger or a wood ledger. For steel ledger applications, multiple self-tapping screws are used to attach the steel ledger directly to the hanger. For a wood ledger, prior to pouring the concrete, carriage bolts are inserted through the square holes in the ledger attachment portion. After the concrete is poured and sufficiently cured, the wood ledger is attached to the hanger using the inserted carriage bolts.
An example of the structural hanger in use with a wood ledger is shown in FIG. 2. The hanger 6 is shown with dashed lines to indicate it has been embedded into a formed concrete wall 9. The wall is contained front and rear with a stay-in-place wall form 8. These forms are commonly made from encapsulated polystyrene (EPS). The wood ledger is attached to the hanger with two carriage bolts 7 inserted through the square holes in the joist hanger.
An example of the structural hanger in use with a wood joist is shown in FIG. 3. The structural hanger 10 in this case does not have a right-angle bend where it exits the wall. The hanger is shown with dashed lines indicating its embedded portion into a formed concrete wall 11. The wall is contained front and rear with a stay-in-place wall form 12. The wood joist 13 is attached to the ledger hanger with two (2) carriage bolts 14 inserted through the square holes in the joist hanger.
In the preferred embodiment, the structural hanger is made from a single piece of stamped 14-gauge galvanized steel. Other appropriate and acceptable embodiments may be used and shall include but not be limited to alternate materials and thicknesses for the ledger hanger, differently shaped embedment holes, differently shaped attachment through-holes, different types of fasteners for attaching the ledger to the hanger and hangers comprising multiple pieces.