1. Field of the Invention
This application is directed toward a two-piece track system for use in building construction, particularly for use in the interior and/or exterior wall of a building.
2. Description of the Related Art
Two-piece track systems for use in building construction are generally well known, as are two-piece track systems for use in the exterior and/or interior wall of a building that can allow for independent environmental movement of the tracks relative to one another. Two-piece track systems generally resemble both an outer U-shaped (or some other similar shaped) elongated tube, or track, and an inner U-shaped (or some other similar shaped) elongated tube, or track. Typically, the inner track is designed to receive or cover the ends of wall studs, and the outer track is designed to receive the inner track. Header tracks, including slotted tracks, are commonly used in the construction industry, including in the exterior walls of buildings. They generally resemble a U-shaped (or some other similarly shaped) elongated channel capable of receiving or covering the ends of wall studs and holding the wall studs in place.
The slotted tracks generally have a web and at least one flange. Typically, the track includes a pair of flanges, which extend in the same direction from opposing edges of the web. Along the flanges of the slotted tracks generally is a plurality of slots. When the wall studs are placed into a slotted track, the plurality of slots accommodate fasteners to permit attachment of the wall studs to the slotted track. The slots allow the wall studs to move generally orthogonally relative to the track. In two-piece track systems, independent movement of the tracks is sometimes desirable. The inner track is generally not confined in all directions, and thus is able to move independently from the outer track. Often times in use, the inner track is able to generally slide alongside the outer track in a horizontal or longitudinal direction relative to the outer track. In those areas of the world where earthquakes are common, this longitudinal or horizontal movement is important. If the inner track were not allowed to move freely in a generally longitudinal or horizontal direction, the stability of the wall and the building might be compromised. Furthermore, if the wall studs are rigidly attached to the slotted track and not allowed to move freely in at least one direction, the stability of the wall and the building might be compromised. With the plurality of slots, the wall studs are free to move.
Also along the flanges of the slotted tracks generally are areas for attachment of exterior sheathing elements. However, in many current slotted tracks, the slots take up the majority of the flanges of the track, leaving little room for attachment of exterior sheathing elements. For example, angle-shaped sheet metal tracks are commonly used on the outsides of wall studs. Each of these angle-shaped sheet metal tracks has a top web portion and one extending flange portion. The extending flange portion normally has a plurality of slots, but the slots extend nearly to the intersection of the flange and web. Because of this, there is little room for attachment of exterior sheathing elements to the flange of the slotted track.
In building construction it is not uncommon to have pieces of sheathing, or façade, attached to the outside of the building. These pieces of sheathing generally extend vertically alongside and down the exterior portion of the tracks and wall studs. The pieces of sheathing are attached to the tracks and/or wall studs by some connection means such as a screw or screws. In current two-piece track systems, the outer track's greatest width is larger than the inner track's greatest width. This creates an uneven outer surface for attachment of the sheathing. As a result, often sheathing elements flare out at their ends to accommodate for the uneven surface created by the different track widths.
Also, it is often difficult to keep the inner track from pulling or slipping away relative to the outer track during the installation procedure. In current two-piece track systems, screws are used to temporarily hold the outer and inner tracks in place during construction. If these screws are not removed after the wall is framed, the inner track will not be able to move as is desired.
It is also desirable or even mandatory to provide fire block arrangements at one or more linear wall gaps, which may be present between the top, bottom or sides of a wall and the adjacent structure. The fire block arrangements often involve the time-consuming process of inserting by hand a fire resistant material into the wall gap and then applying a flexible sealing layer to hold the fire resistant material in place. More recently, heat-expandable intumescent fire block materials have been integrated into the top or bottom track of the stud wall assembly.