The disclosure relates generally to mull posts for use in exterior or other door assemblies, and more particularly to a reinforced mull post for use in an exterior or other door assembly.
Entryway systems used in residential and commercial buildings include single and double door assemblies having one or more sidelights or sidelight panels flanking the door(s). Such entryway systems are typically fabricated using vertical mullions or mull posts positioned between the door(s) and the associated sidelight or sidelight panel to connect the structures. When these entryway systems are used in coastal regions of the country, it is desirable that the systems be capable of withstanding the extremely high pressures caused by high winds as well as impacts caused by flying debris.
Recently, extruded polymer mull posts made from inexpensive materials such as polyvinyl chloride (PVC) have been used. While polymer mull posts may not be as susceptible to breaking or splitting like traditional wood mulls, they still may be highly susceptible to deflection or bending when exposed to high pressure, thus compromising the integrity of the entryway system as previously explained.
In addition to the high design pressure requirements in hurricane prone regions, building codes in coastal regions also typically require that an entryway withstand a direct impact by airborne debris such as tree limbs. Traditional solid wood mull posts and extruded polymer mulls may be highly vulnerable to such impacts, again, for the reasons previously stated.
Thus, a need exists for an entryway system incorporating high strength mull posts that meet or exceed design requirements imposed by stringent building codes in coastal regions. Such mull posts should be inexpensive to produce, and should emulate the appearance of traditional wooden mulls so that they are acceptable for use in private residences.
According to one aspect, a reinforced mull post assembly is disclosed. The reinforced mull post assembly, comprises: a mull post comprising a two piece housing formed by an elongated support piece and a stop piece coupled together by interlocking flanges, the support piece having external first and second support faces and the stop piece having first and second legs forming first and second raised stops laterally offset from the first and second support faces, respectively, the housing including a central chamber therein; the interlocking flanges including the stop piece having first flanges, each having a recess therein, and the support piece having second flanges, each second flange having a rib received within the corresponding recess of the corresponding first flange; the central chamber including a longitudinal void section and a transverse void section; and a reinforcing member disposed within the central chamber and including portions within the longitudinal void section and the transverse void section, the portion of the reinforcing member in the longitudinal void section including an upper wood portion and a lower durable portion, connected end to end by a glued finger joint.
According to another aspect, a reinforced mull post assembly is disclosed. The reinforced mull post comprises: a mull post comprising a two piece housing formed by an elongated support piece and a stop piece coupled together by interlocking flanges, the stop piece having first and second legs forming first and second raised stops disposed laterally outside the support piece and offset from external surfaces of the elongated support piece, the housing including a central chamber therein. The interlocking flanges include the stop piece having first flanges and the support piece having second flanges, one of the first and second flanges having a protuberance and the other of the first and second flanges having a recess that receives the protuberance. The central chamber includes a longitudinal void section and a transverse void section; and a reinforcing member is disposed within the central chamber and including a longitudinal portion disposed within the longitudinal void section and a pair of opposed transverse portions received in the transverse void sections, the longitudinal portion of the reinforcing member including an upper wood portion and a lower durable portion, connected end to end by a glued finger joint.
According to another aspect, a reinforced mull post assembly is disclosed. The reinforced mull post comprises: a mull post comprising a two piece housing formed by an elongated support piece and a substantially U-shaped stop piece coupled together by interlocking flanges, the support piece having first and second support faces and the substantially U-shaped stop piece having first and second ends forming first and second raised stops disposed laterally outside the support piece and offset from external surfaces of the elongated support piece, the two-piece housing including a central chamber therein; the interlocking flanges including the substantially U-shaped stop piece having first flanges and the support piece having second flanges, one of the first and second flanges having a protuberance and the other of the first and second flanges having a recess that receives the protuberance; the central chamber including a longitudinal void section and a transverse void section; and a reinforcing member disposed within the central chamber and formed of a different material than the substantially U-shaped stop piece and the support piece, the reinforcing member including an upper wood portion and a lower durable portion, connected end to end by a glued finger joint.
The present disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawing. It is emphasized that, according to common practice, the various features of the drawing are not necessarily to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Like numerals denote like features throughout the specification and drawing.
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The stop portion 26 of the mull post 16 may further have an exposed face portion 40 that extends along the length of the mull post 16 and is exposed to the exterior of the building in which the door assembly 1 is installed. In the illustrated embodiment, this exposed face portion 40 is flat, however, it will be appreciated that a the face portion may be provided in any of a variety of different decorative shapes to result in a desired external appearance for the mull post 16. This exposed face portion 16 may have a surface that can be painted or otherwise finished in any manner to provide the appearance of a traditional wood mullion.
While the external appearance of the mull post 16 provides the look of a single-piece construction, the interior of the exemplary mull post 16 of
In one embodiment, the polymer profile portion 42 that includes support portion 24 and stop portion 26, is fabricated from a thermoplastic material, such as polyvinyl chloride (PVC), and is formed using an extrusion process, although other formation processes such as molding may also be used. The first reinforcing member 44 may comprise engineered wood, such as laminated veneer lumber (LVL). The second reinforcing member 46 may comprise a steel U-channel that wraps around one end of the first reinforcing member 44 to further enhance the strength and rigidity of the resulting mull post 16.
The material of the polymer profile portion 42 may be any of a variety of thermosetting polymers, a non-limiting list of which includes PVC, PE (Polyethylene), PP (Polypropylene), ABS (Acrylonitrile Butadiene Styrene), PC (Polycarbonate), PS (Polystyrene), NYLON and TEFLON. The hollow center 48 may be formed during the extrusion process (where an extrusion process is used), or it may be formed after the profile portion is formed (e.g., by machining from of a solid formed profile).
The first reinforcing member 44 may comprise a sold piece of wood or other material (e.g., a second polymer), or it may comprise plurality of individual plies 50 of material glued or otherwise adhered together to form a multiple ply structure (see
As an alternative to LVL or PVL, the first reinforcing member 44 may be formed from plies 50 made of a mixture of wood and other materials to enhance the strength of the member. For example, some of the plies 50 may be wood veneers while other plies may be plastic, carbon composite, fiberglass, or metal such as aluminum. The use of such non-wooden plies combined with wooden plies may form a first reinforcing member 44 of exceptional strength and resistance to failure under even the most severe load conditions.
The first reinforcing member 44 may also include an upper wood portion 172 and a lower durable portion 174, connected end to end by a glued finger joint (see
As noted, the second reinforcing member 46 may comprise a steel U-channel that wraps around one end of the first reinforcing member 44. In the illustrated embodiment, the second reinforcing member 46 is positioned so that it wraps around the first reinforcing member 44 at the end immediately adjacent the stop portion 26 of the mull post 16 to provide support to the exposed face portion 40, and to provide the mull post with maximum rigidity against flexure in use. As can be seen, the second reinforcing member 42 does not extend the entire width “W” (
As will be appreciated, the second reinforcing member 46 may be provided in shapes other than the U-shape illustrated in the figures. For example, the second reinforcing member 46 could simply comprise a flat metal member positioned on one broad flat side of the first reinforcing member 44, running the entire length of the mull post 16. Alternatively, a pair of flat metal members could be positioned on opposite broad sides of the first reinforcing member 44. In addition, any of a variety of metals can be used, a non-limiting list of which includes aluminum, steel, stainless steel and copper. Further, highly-rigid non-metals such as fiberglass, graphite reinforced polymers, and the like could also be used to form the second reinforcing member 46.
In addition, it will be appreciated that the mull post 16 may be provided with a profile portion 42 and only a single reinforcing member. Thus, in one embodiment the mull post 16 may comprise the profile portion 42 and only the first reinforcing member 44. In another alternative embodiment the mull post 16 may comprise the profile portion 42 and only the second reinforcing member 46.
Where the polymer profile portion 42 is formed by an extrusion process, a cap stock layer 56 may be co-extruded onto the profile portion 42 to provide protection to the profile portion 42 to increase weatherability (e.g., resist UV rays), and to provide a desired finished exterior appearance and/or color to the mull post 16. This cap stock layer 56 may comprise PVC, and may be provided in a thickness range of about 0.4 to about 0.6 millimeters. In one embodiment, the cap stock layer 56 is applied in a thickness of about 0.6 millimeters.
Although the disclosed designs have been disclosed for use in mull post applications, it may also be used to advantage to form the vertical door jambs 8, 10, sills 12 and headers 14 of the door assembly 1. Often, however, only the mull posts 16 are formed using the disclosed reinforced design because the strength of the jambs, sills and headers is not as critical as that of the mull posts since the jambs, sills and header are typically secured directly to the heavy construction framing of the opening into which the door assembly installed. As such, forces imparted to the jambs are typically transferred directly to the framing timbers and splitting and failure of the jambs generally is less a problem that failure of the otherwise unsupported mullion members.
The disclosed mull posts 16, 18 may be attached at their top and bottom ends with screws or other appropriate fasteners to the sill 12 and header, respectively.
With the disclosed door assembly 1 installed in a dwelling that is subjected to the high winds of a hurricane or other storm, the door and panels can be subjected to extreme pressures and consequently extreme inwardly directed forces. These forces are transferred from the door and panels to the reinforced mull posts of the entryway, which, due to their reinforced construction, resist the failure modes common for traditional mull posts and transom mulls. Ultimately, much of the force born by the mull posts 16, 18 are transferred to the vertical jambs 8, 10, the sill 12 and the header 14, and, in turn, to the framing timbers of the building.
A further exemplary mull post design in shown in
Now turning to
Stop component 102 includes internal portion 106 and external portion 108 in the illustrated embodiment. According to other exemplary embodiments, stop component 102 may be formed of a single composition, i.e. a single material. Internal portion 106 may be formed of rigid PVC, polyvinyl chloride, in one exemplary embodiment but may be formed of other suitable polymers, plastics and rigid materials and other exemplary embodiments. External portion 108 may be advantageously formed of wood or a wood composite in one exemplary embodiment but may be formed of plastics, polymers, PVC or other suitable components in other exemplary embodiments. External portion 108 may advantageously have a wood grain outer appearance in one exemplary embodiment. Internal portion 106 includes surface 110 which will be a smooth surface in various exemplary embodiments to aid in slidably receiving an internal reinforcing member when stop component 102 is joined to support component 104. Stop component 102 includes opposed flanges 112 which may alternatively be described as ribs. Flanges 112 each extend laterally inward from the opposed sides of generally U-shaped stop component 102 and are adapted to engage with corresponding flanges 116 of support component 104 shown in
Support component 104 is longitudinal in shape and includes internal portion 126 and external portion 128. Internal and external portions 126 and 128 may be as described for corresponding internal and external portions 106 and 108, respectively, of
Housing 140 defines central chamber 148 which is “T” shaped in the exemplary embodiment and includes longitudinal void section 150 and orthogonally oriented transverse void sections 152.
T-shaped reinforcement member 160 is shown in
According to another exemplary embodiment, T-shaped reinforcement member 160 may be partially or completely surrounded by a second reinforcing member such as second reinforcing member 46 shown in
Mull post 100 shown in
Stop component 102, support component 104 and T-shaped reinforcement member 160 may be securely joined by tight mechanical fittings in combination with the interlocking flanges/ribs or glue or other suitable adhesives may optionally be applied along the interfaces.
Longitudinal slots 144 have a constant width in the illustrated embodiment as first and second support faces 142 each include a thicker ridge portion 170 that defines longitudinal cavity 144.
It should be understood that the embodiments disclosed herein are merely illustrative of the principles of the disclosure. Various other modifications may be made by those skilled in the art which will embody the principles of the disclosure and fall within the spirit and the scope thereof. For instance, the disclosed reinforced mull posts may be used in window frames as well as entryways and may be applied to entryways with a transom and a single sidelight. Application to entryways of other configurations also is envisioned.
This application claims the benefit of U.S. Provisional Application No. 62/334,492, filed May 11, 2016, which application is expressly incorporated by reference herein in its entirety.
Number | Date | Country | |
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62334492 | May 2016 | US |