Patent Publication Number: US-2005115175-A1

Title: Construction compositions and methods

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      This application claims priority under 35 U.S.C. § 119 and applicable foreign and international law of U.S. Provisional Patent Application Ser. No. 60/508,561 filed Oct. 3, 2003 and is hereby incorporated by reference in its entirety for all purposes. 
    
    
     FIELD OF THE INVENTION  
      The invention relates to compositions and methods of constructing door and window systems involving techniques for resisting bowing or warping affects.  
     BACKGROUND OF THE INVENTION  
      Efficient manufacturing of high performance stable wood components has become an important focus of product design in the fenestration industry. Performance standards require that wood components remain straight over time. Another important objective is to reduce the amount of costly appearance grade wood that is used in windows and doors while still maintaining the strength needed for long-term reliably functioning products. Market-driven demands due to increasing product liability along with more stringent building code requirements are making these two issues top priorities in the industry. One approach to containing cost of materials is to use laminated wood components including higher grades of wood for appearance glued to lower grades of wood, such as plywood, or finger-jointed short pieces of scrap wood to give the appearance of solid wood.  
      However, engineered wood composite products are often susceptible to bowing, twisting, crooking or cupping (collectively referred to as “warping” affects). In each instance, a component of the composite tends to deviate from linear or straight orientation, possibly causing compromised mechanical function of a window or door, unwanted gaps around a closed door or window, etc. and other significant problems.  
      A primary cause for engineered wood composite materials to move out of parallel occurs when two pieces of material having different moisture contents are glued together. Maintaining equal moisture content between boards or laminated components is difficult on a mass production basis. Wood, by nature, tends to shrink when you remove moisture and it expands when it absorbs moisture. After laminating wood components together, the differing moisture contents of each component may eventually equalize to the same moisture content over time. The component that had the most moisture originally may shrink more than the other component. This difference in shrinking between components pulls on one piece relative to the other, and causes some degree of movement out of parallel, often resulting in compromised function or appearance.  
      Movement out of parallel may also happen with non-engineered wood components. This movement may be caused by poor kiln drying practices, or because of different densities within the tree based on growing patterns, or stresses on the tree due to wind and other climatic conditions.  
      Another cause of moisture-induced movement in fenestration products may occur after installation. A door or window system may be installed with one surface exposed to an interior climate, and the other surface exposed to an exterior climate. In this instance, moisture, and temperatures may be quite different between the inside and outside resulting in unbalanced or erratic moisture migration causing bowing or warpage of wood components.  
      One approach to maintaining wood components straight, or at least resisting bowing to some extent, is to control moisture migration by applying moisture barriers on various surfaces around a door or window system. However, this approach is inadequate for many door and window systems because unprotected, or unsealed surfaces may still permit moisture migration resulting in warping.  
     SUMMARY  
      Wood components are bonded together to form door or window systems including one or more strengthening sheets at selected locations to resist warping affects. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       FIG. 1A  is a cross-section of a wood composite member for a door or window system.  
       FIG. 1B  is a perspective view of the composite shown in  FIG. 1A .  
       FIG. 1C  is a partial perspective view of the wood composite member shown in  FIGS. 1A and 1B , indicating an additional processing profile.  
       FIG. 2A  is a cross-section of another wood composite member for a door or window system.  
       FIG. 2B  is a partial perspective view of the composite member shown in  FIG. 2A , indicating an additional processing profile.  
       FIG. 3A  is another cross-sectional view of a wood composite member for a door or window system.  
       FIG. 3B  is a partial perspective view of the composite member shown in  FIG. 3A , indicating an additional processing profile.  
       FIG. 4A  is another cross-sectional view of a wood composite member for a door or window system.  
       FIG. 4B  is a partial cross-sectional view of a door jamb incorporating the composite member shown in  FIG. 4A , with additional components.  
       FIG. 5A  is another cross-sectional view of a wood composite member for a door or window system.  
       FIG. 5B  is a partial cross-sectional view of a door jamb incorporating the composite member shown in  FIG. 5A , with additional components.  
       FIG. 6A  is another cross-sectional view of a wood composite member for a door or window system.  
       FIG. 6B  is a partial cross-sectional view of a door jamb incorporating the composite member shown in  FIG. 6A , with additional components.  
       FIG. 7  is a cross-sectional view of another wood composite member for a door or window system. 
    
    
     DESCRIPTION  
      Doors and windows are typically hung in a frame which supports the door or window, and permits a range of movement. There are numerous components included in door and window systems. The components may have complex shapes that need to fit together precisely so that the door or window functions properly and creates a sealed barrier between inside and outside. Door and window system components have numerous faces oriented in different directions, each of which creates the possibility for bowing, twisting, cupping, crooking, shrinking, warping, etc. Bowing affects may be minimized, or at least resisted, by incorporating thin sheets of composite material, for example, phenolic paper, carbon composites, or other composites that a have a high degree of deflection resistance edge-to-edge on the flat plane of the composite. A strengthening sheet may be glued or integrated in a composite material to decrease or eliminate movement across the glued face of the composite and wood laminated connecting surfaces. Strengthening sheets may be incorporated in composites so as not to interfere with the aesthetics of the natural wood finish, while providing the desired stiffening properties. The approach of using a strengthening sheet such as phenolic paper may be applied in many different product configurations depending on the direction(s) of potential movement.  
       FIG. 1A  shows a component referred to as an inside stop  20 . Stop  20  may be attached to the frame of a casement type window or door jamb. Stop  20  includes solid wood component  22  for constructing the exposed area of stop  20  and finger jointed component  24  made of scrap wood for forming the non-exposed area of stop  20 . Strengthening sheet  26 , for example, phenolic paper, is glued in the interface between components  22  and  24 .  
      As shown in  FIG. 1B , stop  20  is susceptible to edge bow or crook affects. An edge bow may occur as indicated by arrow  28 . A face bow may occur as indicated by arrow  30 . A window sash may open or close against the inside stop. Consequently, “edge crook or edge bow” in the stop can cause an unsightly gap between the closed sash part and the stop. Edge crook/bow may be very difficult to straighten out and hold with a fastener such as a nail or screw. A face bow may not be as much of a problem because it may be controlled by putting a nail in the face of the stop which is the normal way the stop is fastened to the frame.  
      One face and one edge of the wood stop is seen on the inside of the window by a homeowner. It may be sold as a stain grade product, so that no composite material may show on the face. The other side of the stop is hidden and can be a lower grade material such as finger-jointed wood, MDF, OSB or plywood for example. Strengthening sheet  26  is placed diagonally the profiled stop so the aesthetics of the stained grade material is unaffected. By placing the composite at an angle offset slightly from opposing corners between components  22  and  24 , bowing across any plane is resisted. The composite is hidden inside the component so that it is not seen after the component is installed. Test data shows an 85% reduction in edge bow/crook affect along the edge of the widest plane of the product. Other test data showed a 91% reduction in face bow affects which would be measured as deflection along the face of the widest plane.  FIG. 1C  shows component  20  as it is finally milled to form a stop or step shape in solid component  22 .  
       FIG. 2A  shows a cross-section of a sash component from a double hung or sliding window product. Sash component  40  includes wood component  42  and strengthening sheets  44  and  46  applied or glued to wood component  44  at a right angle. Strengthening sheets  44  and  46 , for example, may be sheets of phenolic paper.  FIG. 2B  shows potential face bow and edge bow affects, indicated by arrows  48  and  50  respectively. Face bow affects are resisted by strengthening sheet  44 , while edge bow affects are resisted by strengthening sheet  46 .  FIG. 2B  also shows the final profile  52  of sash component  40 . Typically, a window has two sashes that meet together in the middle of the window. A double-hung assembled sash moves up and down. A sliding sash moves side-to-side. The sash component shown in  FIGS. 2A and 2B  is the type of sash that connects in the middle of the window. The difficulty with this component is that any face bow or any edge bow can cause significant problems with the movement and connection in the middle of the sash. The design of the component does not lend itself to the cost effective solution of using a diagonal strengthening sheet, for example, as illustrated in FIGS.  1 A-C. Therefore, the design is modified to put phenolic papers in perpendicular or 90° angles to each other, to control face and edge bowing.  
      Phenolic paper has very little strength or stiffness as you bend the thin face. However, when bending the sheet along an edge, it is very stiff and strong. Accordingly, by opposing the faces of the phenolic papers they act cooperatively to create bi-polar or multi-directional resistance to movement.  
       FIGS. 3A and 3B  show a sash component with exposed visible faces which preclude the design option shown in FIGS.  2 A-B. Sash component  60  includes finger-jointed component  62  connected to solid wood component  64  via strengthening sheet  66  at the internal interface. Veneer sheet  68  is attached to a visible side of sash component  60 .  FIG. 3B  shows final milled profile  70  of sash component  60 . Strengthening sheet  66  resists face bowing in the direction indicated by arrow  72 . However, unlike the design in FIGS.  2 A-B, sash  60  has no strengthening sheet that resists edge bow affects in the direction indicated by arrow  74 .  
      In the sash component shown in FIGS.  3 A-B, it is not possible to get the bi-polar stiffness of perpendicular strengthening sheets as shown in FIGS.  2 A-B because the paper or composite would appear in an exposed area of the sash. A single sheet of phenolic paper is used which provides stiffness in one direction for this particular item.  
       FIGS. 4-6  show various door frame designs. In this series of figures, two types of exterior door frames are shown for supporting a door that swings into a building. FIGS.  4 A-B show a door frame design that uses a brick mould exterior trim. In FIGS.  5 A-B and FIGS.  6 A-B, the brick mould is eliminated and replaced with an extension typically referred to as an “exterior jamb nosing”. Next, a plastic or aluminum nailing flange is installed in the groove on the back side of the jamb to attach and flash the door frame. This type of door frame design is common with an aluminum or vinyl clad door frame. The reinforcement configurations shown in  FIGS. 4-6  may also be applied to a sliding door jamb in contrast to a swinging door jamb. A sliding door frame would require a different profile for the jamb. Straightness and strength are primary requirements of door frames because they connect the door to the building structure. One of the biggest bowing issues in a door frame is the face bow. If the frame bows toward the door, it may pinch against the door making it difficult to open and close the door or sash. Likewise, if it bows away from the door, it may create a gap. causing air leakage.  
      Another market-driven issue is the overall strength of the door frame, especially with respect to wind load building codes especially in hurricane regions. Highly restrictive codes exist and are being incorporated in such places as Dade County, Florida and much of the East Coast. Buildings are required to have very high impact ratings for doors and windows, especially in hurricane-prone areas. The strength of the frame, as well as the window, stop shown in FIGS.  1 A-C, are a critical component when measuring the overall window or door&#39;s ability to meet the impact requirements. Drawings  4 - 6  provide designs that achieve benefits of increased strength and stiffness, in addition to bowing resistance.  
       FIG. 4A  shows door jamb component  80  including hidden component  82  and exposed component  84 . Hidden component  82  may be a lower quality composite such as finger-jointed stock, MDF, OSB, or plywood, etc. Exposed portion  84  may be solid wood or may be lesser quality material that will eventually be painted. Strengthening sheets  86  and  88  are provided at a right angle configuration, as shown. Strengthening sheet  90  is optionally provided at the interface between hidden component  82  and exposed component  84 .  FIG. 4B  shows end  80  after further processing and installation in a wall. Rabbeted edge  92  is cut into exposed component  84  to accommodate door  94 . Weather strip  96  is provided to seal the gap between door  94  and jamb component  80 . Strengthening sheets  86  and  88  are ultimately hidden by finishing material such as a vinyl wrap, a foil wrap or a wood veneer wrap. Building frame  98  has casing  100  on an interior side and brick mould  102  on an exterior side to finish the jamb installation.  
      The design shown in FIGS.  4 A-B is similar to the bi-polar perpendicular paper/composite construction discussed in FIGS.  2 A-B. The phenolic paper across the exterior face plane of the door jamb provides a stiffness, and also a hard face that can be painted or wrapped with a vinyl or foil film for a hard, low-maintenance finished surface. A wood appearance may also be achieved by applying a wood veneer over the phenolic papers. Then on a 90° plane phenolic paper is applied one or two other locations to work against the other horizontal face papers to provide bow resistance in all four directions. The internal phenolic papers can be incorporated internally or on an outer edge of the jamb if paint will eventually be applied to the exterior edge. Phenolic paper provides a smooth hard painted, vinyl or foil-wrapped surface. If a customer wants a stained grade wood finish, then a wood edge may be bonded over the phenolic paper.  
      FIGS.  5 A-B show another jamb design. In this case, two strengthening sheets are applied in parallel. As shown in  FIG. 5A , jamb component  110  includes hidden component  112  and exposed component  114 . Hidden component  112  may be finger-jointed stock or LVL, plywood, etc. Exposed component  114  may be solid wood. Alternatively, exposed component  114  may be lesser quality stock if it will eventually be painted. External component  116  should be solid wood to improve impact toughness or maybe another appropriate material. Strengthening sheets  118  and  120  are applied in parallel planes on front and rear faces, respectively of jamb component  110 .  
       FIG. 5B  shows jamb  100  after further processing and installation in a wall. Rabbeted edge  122  is cut to accommodate a door. Weather stripping  124  is provided to seal the gap between the door and the stop. Another rabbet cut is made on the external side of the jamb. Slot  126  provided on the backside of jamb component  110  for receiving a plastic or aluminum nail flange.  
      In some instances, a bowing affect may be caused rather than inhibited when two strengthening sheets are used on opposing parallel surfaces if the sheets are not approximately the same size. This may be caused by moisture penetrating one of the faces more or less than the other. Another issue may relate to the fact that the phenolic paper shrinks and grows with heat and cold. If the two papers on opposing parallel faces are not close to the same dimensions then bowing or cupping may occur. Cupping occurs when the lineal edges of the part curl up or down. This may be partially controlled by putting a vertical paper in the construction that is perpendicular to horizontal paper. However, cupping may still occur. Edge cupping may or may not be a significant functional problem depending on where the cupping occurs.  
      As shown in  FIG. 5B , the interior rabbeted edge of jamb component  110  may need to retain a wood appearance so that it can be stained to match the interior trim. On the opposite face, which is the back side of the jamb, there is a full width flat surface with no rabbeted profile cuts so that it is easier to laminate a strengthening sheet across the entire back side of the jamb. However, the problem of not balancing pieces with strengthening sheets of equal size may cause the wood to move either cupping or bowing. The rabbeted area where the door closes and is latched to the door frame is crucial for functioning of the door. If the rabbeted portion curls, cups or bows, this may cause the frame to pinch against the edge of the door and cause performance issues, and also may make it difficult to open or close the door. Accordingly, in the design shown in  FIG. 5A , strengthening sheets  118  and  120  have substantially equal widths or areas.  
      Depending on the door frame design, it is sometimes desirable to make an additional rabbeted cut opposite the rabbeted cut that the door closes against. However, any cupping that may occur on this rabbeted cut is not as significant of a performance issue because no door closes against it. Accordingly, as shown in  FIG. 5B  strengthening sheet  130  may be applied on the back side of external rabbeted portion  132 . One benefit to having the wider paper on the back side of jamb component  110  is that it will extend to the outside edge of the door jamb and may provide a hard surface that is less likely to dent or to be damaged in this high traffic area. Also, if the door frame profile is wrapped with a moisture barrier like a vinyl or foil film, then the face opposite the paper will have a moisture barrier that will prevent moisture-induced bowing.  
      FIGS.  6 A-B shows another example of a door jamb with reinforcing strengthening sheets. The jamb shown in FIGS.  6 A-B is similar to the one described above and shown in FIGS.  5 A-B, except there is an additional strengthening sheet, or two sheets, incorporated into the jamb at right angles to the other two strengthening sheets. Shown in  FIG. 6A , jamb component  140  includes hidden component  142  which is connected to exposed component  144  and external portion  146 . End component  142  may be made of finger jointed stock or some other lower quality wood composite material. Exposed component  144  may be made of solid wood if the grain will be exposed in the final product. Alternatively, exposed component  144  may be made of a lesser quality wood composite material if it is going to be painted. External portion  152  may be made of hard wood to improve impact toughness. Strengthening sheets, for example, phenolic paper  148 ,  152 , and  150  are provided as shown. Optionally, another strengthening sheet  154  may be applied between end component  142  and external component  146 .  FIG. 6B  shows jamb component  140  after further processing. Rabbeted face  156  is created to accommodate a door. External portion  146  may also be rabbeted as shown. A plastic or aluminum nail flange may be inserted in slot  160  at the backside of jamb component  140 .  
      The jamb system shown in FIGS.  6 A-B incorporates the perpendicular strengthening sheet design to provide increased stiffness, strength and stability in multiple directions. Additionally, having a phenolic paper on the outer edge of external portion  152  protects damage prone parts of the door frame. Optionally, phenolic paper may be applied in the center of the jamb across the full width.  
       FIG. 7  shows a cross section of a stile or a rail for a door or window. Door or window component  160  includes internal portions  162  and  164  which may be made of finger jointed stock or other low grade wood composite material. End portions  166  and  168  will be exposed, and are therefore generally made of solid wood. If end portions  166  and  168  will eventually be painted, then they may be made of lower grade wood composite material. End portion  166  has a groove for receiving an edge of a wood panel or glass panel  170 . Vertical strengthening sheets  172 ,  174 , and  176  are incorporated into door or window component  160  in a perpendicular orientation to panel  170 . Additional strengthening sheets  180  and  182  are applied in parallel planes perpendicular to the other strengthening sheets  172 ,  174 , and  176 . Finally, wood veneer sheets  180  and  182  may be applied to give the appearance of solid wood on the face and back side of stile or rail  160 .  
      The door or window component  160 , as shown in  FIG. 7 , uses a perpendicular phenolic paper configuration to provide a more stable door and window stile or rail for the fenestration industry. Phenolic paper also provides a moisture barrier that helps control moisture migrating into the wood substrate which may help to prevent face and/or edge bowing of the stile or rail in the door or window. Moisture barriers are also incorporated on each edge of the stile or rail, to stop moisture migration from the edge. In one example, two papers are used on the vertical edges. In other examples, additional vertical papers/composites are incorporated into the stile or rail, in combination with at least two horizontal papers to balance the moisture migration and strength and stiffness benefits.  
      The specific embodiments disclosed and illustrated herein should not be considered as limiting the scope of the invention, as understood by a person having ordinary skill in the art. Numerous variations are possible within the scope of the appended claims. Subject matter of the invention includes all novel and non-obviousness combinations and subcombinations of the various elements, features, functions, and/or properties disclosed herein.