Abstract:
A window frame, door frame, or other construction component is constructed using hardboard for improved decay and insect resistance properties. Among the several different embodiments are a frame constructed entirely of hardboard and a frame having an internal wood and external hardboard section.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates generally to door frames, window frames, and other construction products.  
         BACKGROUND OF THE INVENTION  
         [0002]    When building a new home, interior and exterior walls are typically framed in a manner that leaves openings where doors are to be placed. The framed opening includes load-bearing structural members, but usually does not include the frame on which the door itself is to be hung. Rather, a separately constructed door frame having a header, two side jambs, and sometimes a sill, is placed in the framed opening and nailed or otherwise secured. The door may be pre-hung, meaning that it is attached to a side jamb before the door frame is secured, or may be hinged to the door frame after the frame is secured to the opening.  
           [0003]    Over the years, there have been many advances in the construction of door frames to enable them to better fit inside a door opening and to use different materials when building the frame. For example, door frames are often built with small pieces of lumber, using finger joints to attach numerous small pieces of wood together to make an entire frame. The use of multiple sections of lumber is much cheaper than building frames from single, clear sections of wood, and produces less wood waste by using small pieces.  
           [0004]    More recently, some wood products have been made from engineered wood, including materials sometimes called “hardboard.” In general, engineered wood is a wood fiber composite made from a blend of wood fiber and resins in combination with paraffin wax, plastic, or other additives. Hardboard is a particular type of engineered wood. To date, hardboard has been primarily used in aesthetic trim applications, and is typically described as a nonstructural decorative trim product that is generally not used where structural lumber properties are required.  
           [0005]    In one case, door frames have incorporated a small amount of extruded engineered wood at the portion of the frame that contacts the floor in order to improve the ability of the frame to withstand decay caused by moisture and insects. In U.S. Pat. No. 6,122,882, Hagel describes such a door frame constructed from an extruded engineered wood product attached to the bottom of door frame side jambs via finger joints. The Hagel frame also makes use of multiple finger-jointed lumber pieces, as is common in the industry.  
           [0006]    Although the Hagel product theoretically offers advantages in decay resistance, it suffers from a number of disadvantages as well. For example, it only offers decay resistance properties for a small section at the base of the door frame. But exterior door frames may be subject to water or insect-based decay over any portion of the frame that extends outside the building. In addition, the Hagel product incorporates an additional finger joint in a frame made from multiple pieces of lumber. Ideally, the number of finger joints should be kept to a minimum to enhance both structural and aesthetic qualities of the door frame. Moreover, by using two different materials, the transition may be visible and the two materials may take paint or stain differently depending on the materials chosen. Still further, it can be complicated and expensive to produce an extruded decay resistant material and join it to a wood piece to create a uniform, smooth transition.  
           [0007]    Consequently, there is a need for an improved decay-resistant frame product for use with doors, windows, and other settings that overcomes some of the above problems.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention comprises a frame for use with doors, windows, or other areas. In a preferred embodiment, the frame includes a top jamb, two side jambs, and an optional sill. Each of the jambs and the sill are made from engineered wood to provide resistance against decay and insect infestation.  
           [0009]    In accordance with further preferred aspects of the invention, one or more of the top jamb, side jambs, and sill include a dado and are joined together using glue, staples, or nails.  
           [0010]    In accordance with other preferred aspects of the invention, the frame may alternatively be constructed such that each of the top jamb and side jambs includes an interior section and an exterior section. In this embodiment, the interior section is made from wood while the exterior section is made from hardboard. If a sill is included, it is preferably constructed entirely from hardboard.  
           [0011]    In accordance with still further preferred aspects of the invention, the embodiment having interior wood and exterior hardboard sections may also alternatively include lower sections of the side jambs that are constructed entirely of hardboard.  
           [0012]    In accordance with yet other preferred aspects of the invention, a door frame constructed in accordance with any of the preferred embodiments may also include hinge mortises, lock mortises, a door-engaging shoulder, and weather stripping.  
           [0013]    In accordance with still further preferred aspects of the invention, any of the above alternative constructions of the present inventions may be applied to other frame settings, particularly including window frames.  
           [0014]    In accordance with further preferred aspects of the invention, construction materials are produced in which the construction material has two sections including a wood section and a hardboard section. Such a construction is useful for materials intended to be used in environments in which a portion of the material will be internal and a separate portion will be external. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings.  
         [0016]    [0016]FIG. 1 is a perspective view of a preferred door frame;  
         [0017]    [0017]FIG. 2 is a perspective view of an alternate embodiment of a preferred door frame;  
         [0018]    [0018]FIG. 3 is a perspective view of another alternate embodiment of a preferred door frame;  
         [0019]    [0019]FIG. 4 is a perspective view of another alternate embodiment of a preferred door frame;  
         [0020]    [0020]FIG. 5 is a perspective view of a preferred window frame;  
         [0021]    [0021]FIG. 6 is a perspective view of a preferred brick mold; and  
         [0022]    [0022]FIG. 7 is a perspective view of a preferred mull post. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]    A door frame constructed in accordance with this invention is illustrated in FIG. 1. The frame  10  includes a substantially vertical first side jamb  20 , a substantially vertical second side jamb  21 , and a substantially horizontal top jamb  30 . Each of the jambs includes a shoulder  25  on an interior surface that engages a door when the door is closed. The second side jamb  21  includes three hinge mortises  24 . A hinge is attached at one end to each of the hinge mortises  24  and at the other end to a door. Although three hinge mortises  24  are illustrated, any number of hinge mortises and corresponding hinges can be used to carry a door, consistent with this invention. Likewise, while it is convenient for the hinge mortises to be provided in the completed frame  10 , the frame may alternatively be constructed without the hinge mortises  24 . In such a construction, the hinge mortises would be chiseled or otherwise formed at the installation site.  
         [0024]    The first side jamb  20  may also include a pre-formed lock mortise for receiving a strike plate, as well as one or more pre-drilled holes for receiving a latch or dead bolt. The lock holes or mortises may be particularly useful in combination with a pre-hung door, because corresponding holes may be drilled in the door to accommodate a door knob or dead bolt lock.  
         [0025]    In the preferred embodiment as illustrated in FIG. 1, the frame  10  is constructed entirely from hardboard. As used in this patent specification, hardboard refers to any of a variety of engineered wood fiber composite materials. The hardboard used in the preferred frame of this invention is constructed from resin, wax, a binder, and lignocellulosic material. To improve the structural integrity for use in a frame, the wood fiber material is preferably from hardwoods such as oak, poplar, or maple. Heat and pressure are applied to the treated lignocellulosic material to form a consolidated wood product. A presently preferred hardboard is commercially available-under the trademark MiraTE® and is described in one or more of U.S. Pat. Nos. 6,030,562; 5,993,709; 5,980,798; and 5,677,369. Other examples of suitable engineered products include Extira made by Craftmaster, Inc.; MEDEX made by Medite Corp.; Fiberstrate made by Georgia Pacific; Engineered Wood made by Temple-Inland Forest Products; and ABTCO Hardboard made by Louisiana-Pacific Corp.  
         [0026]    The hardboard used for the jambs is preferably produced in blanks that are appropriately sized for use in a door frame. A common size for door jambs is about 1¼ inches thick by 4⅝ inches wide. The blanks are then machine molded to produce the shoulder  25 , mortises, rounded corners, and a smooth finish. Although pre-sized blanks are preferred, the jambs may alternatively be made from larger sheets of hardboard, such as 4′×8′ sheets that are commercially available. The sheets are ripped lengthwise into blanks that are 4⅝ inches wide, then machined as described above. In yet another alternate embodiment, the jambs may be extruded to form a shape that includes the shoulder, then machined to produce the mortises.  
         [0027]    The use of hardboard for the entire frame  10  produces a door frame that is decay resistant over its entire surface. In addition, the use of an engineered product makes it easier to produce the frame with single, continuous planks for each of the top jamb  30 , first side jamb  20 , and second side jamb  21 . Nonetheless, any of the jambs of the frame  10  can be comprised of separate pieces of hardboard joined together via finger joints or other means.  
         [0028]    The top jamb  30  is joined to each of the first side jamb  20  and second side jamb  21  to form a substantially 90 degree joint. Preferably, the top jamb  30  includes a dado at each end to receive the side jambs. The top and side jambs are then attached using glue, staples, nails, screws, or other fastening means.  
         [0029]    Any of the preferred or alternate embodiments of the door frame may also include a bottom sill  60 , as illustrated in FIG. 4. The sill  60  is constructed from hardboard and is attached to the side jambs in the same fashion as the top jamb. Although not illustrated, the sill  60  or any of the top or side jambs may also include weather-stripping attached to interior surfaces to provide a better seal between the door and the frame. Where weather-stripping is desired, a slot (not shown) is formed along appropriate portions of the shoulder  25  of the frame to receive a weather-stripping tab to attach the weather-stripping. Likewise, while the sill and jambs are illustrated as being generally rectangular in shape, they may include molded portions that provide beads, coves, rounding, or other functionally or aesthetically desired shapes.  
         [0030]    An alternate embodiment of the frame is illustrated in FIG. 2. As with the prior embodiment, this alternate embodiment comprises a top jamb, two side jambs, and an optional sill. Thus, the frame  40  includes a first side jamb  20 , and a second side jamb  21 , each attached to a top jamb  30 . In this case, however, the frame includes an interior portion made of wood and an exterior portion made from hardboard. As used in this specification, the terms interior (or internal) and exterior (or external) refer to portions of the frame that are generally inside or generally outside the room or building that is enclosed by the door. Thus, for example, in a frame used with an exterior door of a house, the interior side of the frame is the portion of the frame extending inside the house, while the exterior portion of the frame extends to the outside of the house.  
         [0031]    The first side jamb  20  includes an interior wood side  28  joined to an exterior hardboard side  29 . The top jamb  30  likewise includes an interior wood side  32  joined to an exterior hardboard side  31 , while the second side jamb includes an interior wood side  26  joined to an exterior hardboard side  27 . The two side pieces in each case are preferably joined together using glue. If an optional sill is included, it is preferably formed entirely of hardboard, though it may also be formed using wood and hardboard portions.  
         [0032]    Yet another alternate embodiment is illustrated in FIG. 3. As with the embodiment of FIG. 2, this version incorporates interior wood and exterior hardboard sides of the frame. In this case, however, the lowermost portion of the side jambs  20 ,  21  are constructed entirely from hardboard. Thus, the first side jamb  20  includes an interior section  28  made from wood, an exterior section  29  made from hardboard, and a lower section  51  made entirely from hardboard. The second side jamb  21  likewise includes an interior section  26  made from wood, an exterior section  27  made from hardboard, and a lower section  52  made entirely from hardboard. The lower portions  50 ,  51  need not be very long, and preferably extend upward no more than one quarter of the way toward the top jamb  30 .  
         [0033]    Although the present invention has been described above in use with a door frame, it may also be used in other frame constructions, particularly including window frames. FIG. 5 depicts a typical window frame  70  having a header  72 , side frame members  74 ,  76 , and a sill  78 . In the example depicted in FIG. 5, the window includes an upper window pane  84  and lower window pane  82  in which the lower pane  82  is configured to open by sliding upward. The window also includes a grille comprising vertical and horizontal dividers  80 . Numerous alternative window constructions are also possible, including single-pane windows and windows that open in other ways.  
         [0034]    The window frame  70  is preferably constructed entirely from hardboard, as with the preferred door frame of FIG. 1. Thus, the header, sill, and side members are constructed from hardboard.  
         [0035]    Alternatively, the window frame may be constructed using a combination of wood and hardboard, as with the door frame of FIG. 2. In such an embodiment, the header  72  and side members  74 ,  76  include an internal wood portion and an external hardwood portion joined together by glue. The sill  78  is preferably constructed entirely from hardboard, but may alternatively be constructed in two sections as with the other frame members.  
         [0036]    In yet another alternate embodiment, the window frame  70  is constructed much like the door frame of FIG. 3. Thus, it includes a header  72  having an internal wood portion and external hardboard section. The sill  78  is constructed entirely of hardboard. Each of the side members  74 ,  76  is constructed consistent with the side jambs depicted in FIG. 3, so that they include internal wood portions, external hardboard portions, and a lower section made entirely from hardboard.  
         [0037]    Windows are commonly produced in a double pane configuration. In such a construction, the grille is often placed between the panes for ease in cleaning and to protect it against the elements. In some cases, a grille or mullions appear either inside or outside the window pane. In either embodiment, the present invention includes an optional grille or window mullions constructed entirely from hardboard. By using hardboard for the external grille, mullions, and sill, the window frame is highly resistant to damage from weather and infestation.  
         [0038]    Frame and trim members can also be constructed for additional uses besides those described above. For example, frames and posts for use in framing patio doors or sliding glass doors can be constructed entirely from hardboard or from a construction material having internal wood and external hardboard sections. FIGS. 6 and 7 depict a brick mold  90  and mull post  100 , respectively. A brick mold is typically used as trim around a door frame, and preferably includes beads, coves, or other aspects that are aesthetically pleasing. The brick mold  90  such as that depicted in FIG. 6 is used around the entire door frame, to cover the gap between the door frame and the section of wall it is adjacent to. In the preferred embodiment, the entire brick mold is constructed from engineered wood and is produced separately from the door frame to be attached later by nails or other fasteners. In alternate embodiments, the brick mold may be formed with the frame members or can be pre-attached to the frame before the frame is installed in the door opening.  
         [0039]    The mull post  100  of FIG. 7 is of the type typically used with a patio door or a door having a side light on either side. The mull post may be used as part of the frame as depicted in FIGS.  1 - 4 , and therefore may be constructed in the same manner as any of the side frame members as discussed above. In addition, it may include mortises for strike plates, hinges, and locks as with the side frame members.  
         [0040]    While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment.