Abstract:
A device and method for determining compliance with building construction codes comprises a block of material with a plurality of planar measuring surfaces separated by appropriate distances that are representative of a maximum or minimum gap space between a door and an adjacent structure, as permitted by industry standards. The appropriate measuring surfaces are inserted in the gap opening between the door and adjacent structure to be tested and quickly and easily indicate whether the gap meets building construction codes. The device functions as one tool to quickly check compliance of all gap openings related to door installations without hindrance from door installation hardware.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
   Not applicable. 
   BACKGROUND 
   1. Field of Invention 
   The present invention relates to the measurement of spatial dimensions of gap openings between door edges and door frame components to determine compliance with industry standards as set forth in construction codes and regulations. 
   2. State of the Art 
   The background art is characterized by U.S. Pat. Nos. 4,345,380; 6,862,815; 6,336,275; 6,807,777; 4,584,774; 5,129,153; 5,329,703; 5,471,759; 7,152,336; 6,308,429; 6,279,241; 6,901,672; 5,666,738; and 6,571,484; the disclosures of which patents and patent application are incorporated by reference as if fully set forth herein. 
   Non-patent background art is characterized on the following Internet pages: www.firedoorinspections.com; www.accurexmeasure.com/gap_&amp;_flush.htm; www bojoinc.com/catalog/product_info.php?products_id=119; www.qualityelev.com/main/tool/dgap.htm; and www.spartantoolsales.com. 
   SUMMARY OF THE INVENTION 
   An embodiment of the present invention provides for the quick and accurate determination of building code compliance for all gap openings related to door installations. A device and method for determining compliance with building construction codes comprises a block of material with a plurality of planar measuring surfaces separated by appropriate distances that are representative of a maximum or minimum gap opening between a door and an adjacent structure, as permitted by industry standards. The appropriate measuring surfaces are inserted in the gap opening between the door and adjacent structure to be tested and quickly and easily indicate whether the gap meets building construction codes. The device functions as one tool to quickly check compliance of all gap openings related to door installations without hindrance from door installation hardware. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a perspective view of an exemplary embodiment of the invention; 
       FIG. 2  is a front elevation view of an exemplary embodiment of the invention; 
       FIG. 3  is a rear elevation view of an exemplary embodiment of the invention; 
       FIG. 4  is a left elevation view of an exemplary embodiment of the invention; 
       FIG. 5  is a right elevation view of an exemplary embodiment of the invention; 
       FIG. 6  is a top view of an exemplary embodiment of the invention; 
       FIG. 7  is a bottom view of an exemplary embodiment of the invention; 
       FIG. 8  shows another embodiment of the invention with tactile locator markers. 
       FIG. 9A  shows a left elevation view of the invention with additional tactile locator markers. 
       FIG. 9B  shows a top elevation view of the invention with additional tactile locator markers. 
       FIG. 10  shows an additional embodiment of the invention with generic measurement indicia and tactile locator markers. 
       FIG. 11  shows the additional embodiment of the invention with an instructional label attached to the rear of the invention. 
       FIG. 12  shows a single door unit describing standard industry nomenclature. 
       FIG. 13  shows a double door unit describing standard industry nomenclature. 
       FIG. 14A  shows a perspective view of one embodiment of the invention being used to check the minimum gap distance near the door handle of a single door unit, configured for right hand operation. 
       FIG. 14B  shows a top view of one embodiment of the invention being used in  FIG. 14A . 
       FIG. 15A  shows a front elevation view of one embodiment of the invention being used near the door handle to check the maximum gap distance. 
       FIG. 15B  shows a top view of one embodiment of the invention being used in  FIG. 15A . 
       FIG. 16  shows a top view of one embodiment of the invention in an alternate, rotated position being used on the door lock side of a single door unit configured for left hand operation. 
       FIG. 17A  shows a top view of one embodiment of the invention being used to check the minimum clearance between the inactive door and the active door of a double door unit configured for left hand operation. 
       FIG. 17B  shows a top view of one embodiment of the invention being used to check the maximum clearance of the double door unit shown in  FIG. 17A . 
       FIG. 18  shows a top view of one embodiment of the invention being used near the door handle and latch of a single door unit configured for left hand operation. 
       FIG. 19  shows a top view of one embodiment of the invention being used on the door lock side of a single door unit, configured for left hand operation, where an intumescent smoke seal has been installed. 
       FIG. 20  shows a perspective view of one embodiment of the invention being used on the hinge side of a single or double door unit. 
       FIG. 21A  shows a front elevation view of one embodiment of the invention being used on the hinge side of a single or double door unit. 
       FIG. 21B  shows a top view of one embodiment of the invention being used to check the minimum clearance on the hinge side of a single door unit or double door unit. 
       FIG. 21C  shows a top view of one embodiment of the invention being used to check the maximum clearance on the hinge side of a single door unit or double door unit. 
       FIG. 21D  shows a top view of one embodiment of the invention being used in an alternate position (rotated 180-degrees) to check the maximum clearance on the hinge side of a single door unit or double door unit. 
       FIG. 22A  shows a perspective view of one embodiment of the invention being used on the top side of a single or double door unit, configured for either left hand or right hand operation. 
       FIG. 22B  shows a cross-sectional view of one embodiment of the invention being used as in  FIG. 22A  to check the minimum clearance of the top gap. 
       FIG. 22C  shows a cross-sectional view of one embodiment of the invention being used as in  FIG. 22A  to check the maximum clearance of the top gap 
       FIG. 22D  shows a cross-sectional view of one embodiment of the invention being used in an alternate position (rotated 180-degrees) to check the minimum clearance of the top gap. 
       FIG. 22E  shows a cross-sectional view of one embodiment of the invention being used in an alternate position (rotated 180-degrees) to check the maximum clearance of the top gap. 
       FIG. 23  shows a perspective view of one embodiment of the invention being used on the bottom side of a single or double door unit when the floor is noncombustible. 
       FIG. 24  shows a side cross-sectional view of one embodiment of the invention being used in  FIG. 23  on the bottom side of a single or double door unit. 
       FIG. 25  shows a side cross-sectional view of one embodiment of the invention being used on the bottom side of a single door unit when a combustible floor is present and threshold-sill unit has been installed. 
       FIG. 26  shows a side cross-sectional view of one embodiment of the invention being used on the bottom side of a double door unit when a threshold-sill unit has been installed and “Americans with Disabilities Act” regulations are considered. 
       FIG. 27  shows a side cross-sectional view of one embodiment of the invention being used on the bottom side of a single or double door unit where a flush bolt is being used when the floor is noncombustible. 
   

   DETAILED DESCRIPTION 
   One Embodiment—FIGS.  1 - 7 ,  11   
     FIGS. 1-7 , and  11  illustrate a door gap gauge  1  that allows for quick and accurate determination of building code compliance for all gap openings related to door installations in accordance with the invention. In one embodiment, door gap gauge  1  was a rectangular block supplying six commonly used gap opening measurement standards, although more or less measurement standards could be supplied, and an attachment means, the entire door gap gauge  1  measuring 3 inches long by 2.5 inches wide, with a maximum thickness of ⅜ inches. For this embodiment, door gap gauge  1  preferably is made from Polyamide (Nylon) 6/6 using an injection molding process, but alternatively can be made from other durable materials such as metal, other plastics, wood, or other materials, using alternative manufacturing processes such as conventional machining, e.g., cutting, milling, or lathing; wire electrical discharge machining (wire EDM); chemical etching machining; abrasive water jet machining; or laser machining, e.g., Stereolithography (SLA), Selective Laser Sintering (SLS), or laser cutting; to name a few. 
   For this embodiment an injection molding process is used to precisely produce accurate parallelism between a first planar reference base  5  and a plurality of first planar measuring surfaces  10 ,  14 ,  18 ,  22 , and  26 , which are the measuring surfaces for measurements 1/16″, ⅛″, 3/16″, ¼″, and ⅜″, respectively; and between a second planar reference base  8  and a second planar measuring surface for ¾″  24 . As seen in  FIGS. 4-7 , the various measuring surfaces  10 ,  14 ,  18 ,  22 , and  26 , are connected directly or indirectly to first reference base  5  by a plurality of connecting surfaces  30  and  32 ;  34  and  36 ;  38  and  40 ;  42 ; and  46  and  48 , for measurements 1/16″, ⅛″, 3/16″, ¼″, and ⅜″, respectively, where the connecting surfaces are shown normal to the measuring surfaces and first reference base  5 , although the connecting surfaces do not have to be normal to the measuring surfaces and first reference base  5 . Measuring surface  24  is connected directly or indirectly to second reference base  8  by a connecting surface for ¾″  50 , which is normal to measuring surface  24  and to second reference base  8  (although the connecting surface does not have to be normal to measuring surface  24  and second reference base  8 ). As shown in  FIG. 2 , 1/16″ measuring surface  10  is further formed by removing the appropriate amount of measuring surface  26  material at 45-degree angle  78  from connecting surface  48 , while ⅛″ measuring surface  14  is further formed by removing the appropriate amount of measuring surface  26  material at a 45-degree angle  78  from connecting surface  46 . 3/16″ measuring surface  18  is further formed by removing the appropriate amount of measuring surface  22  material at 45-degree angle  78  from connecting surface  46 . These 45-degree angle formations provide for equal surface measurement areas for gap measurements 1/16″, ⅛″, and 3/16″, although other material removal angles could be used. All measuring surfaces  10 ,  14 ,  18 ,  22 , and  26 , are within the projected area of first reference base  5 ; while measuring surface  24  is within the projected area of second reference base  8 . 
   An attachment aperture  82  is provided for attaching door gap gauge  1  to another object, such as a key ring. For this embodiment, attachment aperture  82  is circular in shape and approximately 0.25″ in diameter, although other diameters and shapes could be used. 
   A plurality of measurement indicia  54 ,  58 ,  62 ,  66 ,  70 , and  74  representing measurement values of 1/16″, ⅛″, 3/16″, ¼″, ⅜″ and ¾″, respectively, are provided to indicate the thickness of connecting surfaces  30  and  32 ;  34  and  36 ;  38  and  40 ;  42 ;  46  and  48 ; and  50 , respectively, and further indicate the measurement widths represented by measuring surfaces  10 ,  14 ,  18 ,  22 ,  26 , and  24 , respectively. In this embodiment, as shown in  FIG. 2 , measurement indicia  54 ,  58 ,  62 ,  66 ,  70 , and  74  are provided in fractional inches, although other measurement units, such decimal inches, millimeters (mm) or centimeters (cm), may be used, to name a few. 
   For this embodiment, the surface of the finished door gap gauge  1  will have a hardness of R(M)=85-95, although other materials with different hardnesses, and hardness measurements, may be used as long as the finished surface has a suitable resistance to deformation, scratching, abrasion, marring, or cutting when used in the intended application. 
   Optionally, as shown in  FIG. 11 , door gap gauge  1  may include a first instruction label  86 , mounted in a first recessed area  90  on first reference base  5  so that the surface of label  86  is below the surface of reference base  5 . 
   Another Embodiment—FIGS.  8 ,  9 A, and  9 B 
   In another embodiment, a door gap gauge  300  is shown in  FIG. 8  with the addition of a plurality of tactile locator marker groups  302 ,  304 ,  308 ,  312 ,  316 , and  320  providing the user with a tactile indication of measuring surfaces  10 ,  14 ,  18 ,  22 ,  26 , and  24 , for measurements 1/16″, ⅛″, 3/16″, ¼″, ⅜″, and ¾″, respectively. For this embodiment, each tactile locator marker group  302 ,  304 ,  308 ,  312 ,  316 , and  320  includes a tactile directional marker  324  and a subgroup of gap measurement markers  330 ,  334 ,  338 ,  342 ,  346 , and  350 , indicating measurements 1/16″, ⅛″, 3/16″, ¼″, ⅜″, and ¾″, respectively. Tactile directional marker  324  is positioned normal to each subgroup of gap measurement markers at an adequate distance such that a user&#39;s finger can discern tactile directional marker  324 . For this embodiment, tactile locator marker groups  302 ,  304 ,  308 ,  312 ,  316 , and  320  are shown as raised dome shapes, where each raised dome is optimally approximately 0.05-inches in height, although other height distances could be used as long as the tactile touch of the finger can discern the raised dome shapes. Alternatively, tactile locator markers could be raised cylindrical, square or rectangular shapes, to name a few. The horizontal and vertical spacing between raised domes is optimally approximately 0.1-inches, although other spacing distances could be used as long as the tactile touch of the finger can discern the raised dome shapes. 
   Attachment aperture  82  is provided for attaching door gap gauge  300  to another object, such as a key ring. For this embodiment, attachment aperture  82  is circular in shape and approximately 0.25″ in diameter, although other diameters and shapes could be used. 
   Additional Embodiment—FIG.  10   
   In an additional embodiment, a door gap gauge  400  is shown in  FIG. 10  with a plurality of measurement indicia  454 ,  458 ,  462 ,  466 ,  470 , and  474  representing measurement values for a plurality of measuring surfaces  410 ,  414 ,  418 ,  422 ,  426  and  428 , respectively. Measurement indicia  454 ,  458 ,  462 ,  466 ,  470 , and  474  provide a more general indication of measurement widths represented by measuring surfaces  410 ,  414 ,  418 ,  422 ,  426  and  428 , respectively, which can be provided in various measurement units, such as fractional inches, decimal inches, millimeters, or centimeters, to name a few, in order to meet the desired code standard. 
   For this embodiment, as shown in  FIG. 10 , a plurality of tactile locator markers  478 ,  480 ,  482 ,  484 ,  486 , and  488  provides the user with a tactile indication of the measuring surfaces  410 ,  414 ,  418 ,  422 ,  426  and  428 , respectively. For this embodiment, tactile locator markers  478 ,  480 ,  482 ,  484 ,  486 , and  488  are shown as raised dome shapes, but alternatively could be raised cylindrical, square or rectangular shapes, to name a few. 
   Although not shown, optionally, door gap gauge  400  may include a second instruction label  404 , similar to first instruction label  86 , where text indicating measuring surfaces for door gap gauge  1  are replaced with text indicating measuring surfaces  1 ,  2 ,  3 ,  4 ,  5 , and  6  for door gap gauge  400 . Similar to first instruction label  86 , second instruction label  404  is mounted in a recessed area on first reference base  5  so that the surface of second instruction label  404  is below the surface of reference base  5 . 
   Attachment aperture  82  is provided for attaching door gap gauge  400  to another object, such as a key ring. For this embodiment, attachment aperture  82  is circular and approximately 0.25″ in diameter, although other diameters and shapes could be used. 
   Detailed Operation of the Embodiments 
   FIGS.  12 - 27   
     FIGS. 12 to 27  illustrate the method of using door gap gauge  1  for quick and accurate determination of building code compliance of all gap openings related to door installations, although door gap gauge  300  and door gap gauge  400  can be used in a similar manner. The National Fire Protection Association (NFPA) and the American National Standards Institute/international Code Council (ANSI/ICC) maintain the ANSI/NFPA 80 standard (“Standard for Fire Doors and Fire Windows”), and ANSI/NFPA 252 Standard (“Standard Methods of Fire Tests of Door Assemblies”), which codify and reference standards for fire doors and fire windows. Based on these current standards, the following method presents all measurement units in fractional inches, although other measurement units, such as decimal inches, millimeters (mm) or centimeters (cm), may be used, to name a few, depending on a particular standard (e.g., updated standards, International standards, etc.). 
   For example, federal and state building codes, citing ANSI/NFPA 80 and 252 standards, require that for both a single door unit  100  and a double door unit  200 , a strike jamb gap  176 , a hinge side gap  128 , and a top gap  108  have a width measuring no more than ⅛-inch, with a tolerance of no less than 1/16-inch, e.g., 1/16″ (minimum) to ⅛″ (maximum). Further, for wooden double door units, a double door gap  244  must have a width measuring no more than ⅛-inch, with a tolerance of no less than 1/16-inch, e.g., 1/16″ (minimum) to ⅛″ (maximum). For metal double door units, double door gap  244  must have a width measuring ⅛-inch, with a tolerance of no less than 1/16-inch or no more than 1/16-inch, e.g., 1/16″ (minimum) to 3/16″ (maximum). 
   Clearance along the bottom of the door depends on the presence or absence of a noncombustible floor surface  140  and/or a threshold-sill unit  152 , both considered components of a single door unit  100  and a double door unit  200  for this invention. If noncombustible floor surface  140  is present, and extends through the door opening (e.g., on both sides of single door unit  100  or double door unit  200 ), threshold-sill unit  152  is not required. For this case a bottom gap  148  must have a height measuring no more than ¾-inch, as measured to noncombustible floor surface  140 , for both the single door unit  100  and double door unit  200 . 
   If a combustible floor surface  142  is present, threshold-sill unit  152 , which is commonly constructed of non-combustible materials, is required because combustible floor construction shall not be permitted to extend through the door opening. Note that combustible floor surface  142  is considered a component of a single door unit  100  and a double door unit  200  for this invention. For single door unit  100  and double door unit  200 , with threshold-sill unit  152  installed, bottom gap  148  clearance height must be no more than ⅜-inch as measured to a sill top surface  153  of threshold-sill unit  152 . The presence of threshold-sill unit  152  also affects federal and state building codes with regards to individuals with physical disabilities as cited by the International Code Council (ICC)/ANSI A117.1-2003 standard, entitled “American National Standard: Accessible and Usable Buildings and Facilities” and the “Americans with Disabilities Act (ADA)” regulations. To meet these standards, threshold-sill unit  152  cannot cause changes in level (height) greater than ½″ (while also being beveled with a slope not steeper than 1:2 for heights between ¼″ and ½″). When combined with ANSI/NFPA 80 and 252 standards, this requires a maximum bottom clearance of ¼″ (¾″ minus ½″) for the above condition. 
   FIGS.  12 - 16   
   Checking the Strike Jamb Gap—Single Door Unit 
   In one method, as shown in  FIGS. 14A ,  14 B,  15 A and  15 B, door gap gauge  1  is being used to check strike jamb gap  176  clearance for a single door unit  100  made from wood, metal, or other materials. In this method, door gap gauge  1  is used to first check the minimum clearance requirement by utilizing measuring surface 1/16″  10 , as shown in  FIGS. 14A and 14B , which represents a right hand door configuration. First, door gap gauge  1  is inserted such that first reference base  5  faces a door lock side edge  180 , measuring surface 1/16″  10  faces a strike jamb edge  168 , and a contact surface for 1/16″  33  engages a strike jamb face  166  (although engagement is not necessary for device to function correctly). If door gap gauge  1  cannot be inserted in this manner, strike jamb gap  176  clearance fails since strike jamb gap  176  is less than 1/16-inch wide. If door gap gauge  1  can be inserted in this manner, at any location along strike jamb gap  176 , the examination of the minimum strike jamb gap  176  clearance continues. Once inserted, lateral pressure is applied such that first reference base  5  is substantially engaged with door lock side edge  180  (alternately, lateral pressure could be applied such that measuring surface 1/16″  10  is substantially engaged with strike jamb edge  168 ). While maintaining lateral pressure, door gap gauge  1  is then moved in a first measuring direction  500 , which is either in the up direction or the down direction for strike jamb gap  176  clearance (shown as going in and out of the drawing in  FIG. 14B ). If, while moving door gap gauge  1  in first measuring direction  500 , strike jamb gap  176  clearance is less than 1/16-inch, door gap gauge  1  movement will stop, indicating a strike jamb gap  176  clearance failure. Door gap gauge  1  is removed from strike jamb gap  176  at this location and reinserted into strike jamb gap  176  (as described above) just past the failed narrow area, and the procedure continues for the minimum clearance check in order to further define any other failure areas, if they exist. If, while moving door gap gauge  1  in first measuring direction  500 , strike jamb gap  176  clearance is greater than 1/16-inch, door gap gauge  1  movement will not stop, indicating strike jamb gap  176  clearance is adequate for the minimum clearance specification. 
   Once the minimum strike jamb gap  176  clearance is checked, door gap gauge  1  is then used to check the maximum clearance requirement for strike jamb gap  176  by utilizing measuring surface ⅛″  14 . As seen in  FIGS. 15A and 15B  (which shows a top view of  FIG. 15A ), door gap gauge  1  is simply rotated 90-degrees in a counterclockwise direction about a z-axis  9 , and then is inserted such that first reference base  5  faces door lock side edge  180 , measuring surface ⅛″  14  faces strike jamb edge  168 , and a contact surface for ⅛″  37  engages a strike jamb face  166  (although engagement is not necessary for device to function correctly). Once inserted, reference base  5  should engage door lock side edge  180  and measuring surface ⅛″  14  should engage strike jamb edge  168 , such that door gap gauge  1  cannot move significantly in a lateral direction  508 , while still allowing door gap gauge  1  to move in first measuring direction  500  (shown as going in and out of the drawing in  FIG. 15B ). Once inserted, lateral pressure is applied such that first reference base  5  is substantially engaged with door lock side edge  180  (alternately, lateral pressure could be applied such that measuring surface ⅛″  14  is substantially engaged with strike jamb edge  168 ). Door gap gauge  1  is then moved in first measuring direction  500 , which is either in the up direction or the down direction for strike jamb gap  176  clearance. If, while moving door gap gauge  1  in first measuring direction  500 , strike jamb gap  176  clearance is less than ⅛-inch, door gap gauge  1  movement will stop. At this location, strike jamb gap  176  clearance is sufficient if the minimum clearance check for this area has already passed. Door gap gauge  1  is removed from strike jamb gap  176  at this location and reinserted into strike jamb gap  176  (as discussed above) just past the narrow area, and the procedure continues for the maximum clearance check. If, while moving door gap gauge  1  in first measuring direction  500 , strike jamb gap  176  clearance is greater than ⅛-inch, measuring surface ⅛″  14  will disengage from strike jamb edge  168 , (or reference base will disengage from lock side edge  180 , depending on the direction of applied lateral pressure as discussed above), that is, door gap gauge  1  is allowed to move in a lateral direction  508 , indicating a strike jamb gap  176  clearance failure. The strike jamb gap  176  maximum clearance check may continue at other areas along the strike jamb gap  176  in order to further define any other failure areas, if they exist. 
   In another method for checking strike jamb gap  176  clearance, the maximum clearance requirement may be checked first, as described above, followed by checking the minimum requirement as described above, that is, the methodology discussed above is performed in reverse order (where door gap gauge  1  is rotated 90-degrees in a clockwise direction about a z-axis  9  when changing from the maximum check to the minimum check). 
   Either method discussed above for checking strike jamb gap  176  clearance may be implemented in an alternate method by rotating door gap gauge  1  by 180-degrees about a y-axis  7  (see  FIG. 3 ), in either a clockwise or counterclockwise direction, and inserting door gap gauge  1  into strike jamb gap  176 .  FIG. 16  is a top view of a left hand door configuration describing the rotated door gap gauge  1  when used in the maximum clearance check. As the rotated door gap  1  is inserted, first reference base  5  faces strike jamb edge  168 , measuring surface ⅛″  14  faces door lock side edge  180 , and contact surface for ⅛″  37  engages a single door face  103  (although engagement is not necessary for device to function correctly). The methods described above for the maximum clearance check are then repeated to verify adequate clearance. For the minimum clearance check, although not shown, door gap gauge  1  is simply rotated by 90-degrees in a clockwise direction about z-axis  9 , and then is inserted such first reference base  5  faces strike jamb edge  168 , measuring surface 1/16″  10  faces door lock side edge  180 , and contact surface for 1/16″  33  engages single door face  103  (although engagement is not necessary for device to function correctly). The methods described above for the minimum clearance check are then repeated to verify adequate clearance. 
   FIGS.  17 A and  17 B 
   Checking the Double Door Gap—Double Door Unit 
   In one method for checking double door gap  244  clearance for wooden doors, as shown in  FIG. 17A , which shows a top view, door gap gauge  1  is used to first check the minimum requirement by utilizing measuring surface 1/16″  10 . First, door gap gauge  1  is inserted such that first reference base  5  faces an inactive door strike side edge  236 , measuring surface 1/16″  10  faces an active door lock side edge  240 , and contact surface for 1/16″  33  engages an active door face  218  (although engagement is not necessary for device to function correctly). If door gap gauge  1  cannot be inserted in this manner, double door gap  244  clearance fails since the double door gap  244  is less than 1/16-inch wide. If door gap gauge  1  can be inserted in this manner, at any location along double door gap  244 , the examination of the minimum double door gap  244  clearance continues. Once inserted, lateral pressure is applied such that first reference base  5  is substantially engaged with inactive door strike side edge  236  (alternately, lateral pressure could be applied such that measuring surface 1/16″  10  is substantially engaged with active door lock side edge  240 ). Door gap gauge  1  is then moved in first measuring direction  500 , which is either in the up direction or the down direction for double door gap  244  clearance (shown as going in and out of the drawing in  FIG. 17A ). If, while moving door gap gauge  1  in first measuring direction  500 , double door gap  244  clearance is less than 1/16-inch, door gap gauge  1  movement will stop, indicating a double door gap  244  clearance failure. Door gap gauge  1  is removed from double door gap  244  at this location and reinserted into double door gap  244  (as described above) just past the failed narrow area, and the procedure continues for the minimum clearance check in order to further define any other failure areas, if they exist. If, while moving door gap gauge  1  in first measuring direction  500 , double door gap  244  clearance is greater than 1/16-inch, door gap gauge  1  movement will not stop, indicating double door gap  244  clearance is adequate for the minimum clearance specification. 
   Once the minimum double door gap  244  clearance for wooden doors is checked, door gap gauge  1  is then used to check the maximum clearance requirement for double door gap  244  by utilizing measuring surface ⅛″  14 . As seen in  FIG. 17B , which shows a top view, door gap gauge  1  is simply rotated by 90-degrees in a counterclockwise direction about z-axis  9 , and then is inserted such that first reference base  5  faces inactive door strike side edge  236 , measuring surface ⅛″  14  faces active door lock side edge  240 , and contact surface for ⅛″  37  engages active door face  218  (although engagement is not necessary for device to function correctly). Once inserted, reference base  5  should engage inactive door strike side edge  236  and measuring surface ⅛″  14  should engage active door lock side edge  240 , such that door gap gauge  1  cannot move significantly in a lateral direction  508 , while still allowing door gap gauge  1  to move in first measuring direction  500  (shown as going in and out of the drawing in  FIG. 17B ). Once inserted, lateral pressure is applied such that first reference base  5  is substantially engaged with inactive door strike side edge  236  (alternately, lateral pressure could be applied such that measuring surface ⅛″  14  is substantially engaged with active door lock side edge  240 ). Door gap gauge  1  is then moved in first measuring direction  500 , which is either in the up direction or the down direction for double door gap  244  clearance. If, while moving door gap gauge  1  in measuring direction  500 , double door gap  244  clearance is less than ⅛-inch, door gap gauge  1  movement will stop. At this location, double door gap  244  clearance is sufficient if the minimum clearance specification for this area has already passed. Door gap gauge  1  is removed from double door gap  244  at this location and reinserted into double door gap  244  (as described above) just past the narrow area, and the procedure continues for the maximum clearance check. If, while moving door gap gauge  1  in measuring direction  500 , double door gap  244  clearance is greater than ⅛-inch, measuring surface ⅛″  14  will disengage from active door lock side edge  240 , (or reference base  5  will disengage from inactive door strike side edge  236 , depending on the direction of applied lateral pressure as discussed above), that is, door gap gauge  1  is allowed to move in a lateral direction  508 , indicating a double door gap  244  clearance failure (for wooden doors). The double door gap  244  clearance check may continue at other areas along the double door gap  244  in order to further define any other failure areas, if they exist. 
   Checking the minimum double door gap  244  clearance for metal doors is largely identical to that discussed above for wooden double doors, however, since current ANSI/NFPA specifications allow for a 3/16-inch maximum clearance for metal doors, an additional step is required. The method proceeds as above until double door gap  244  clearance is greater than ⅛-inch. At this location, measuring surface ⅛″  14  will disengage from active door lock side edge  240 , (or reference base  5  will disengage from inactive door strike side edge  236 , depending on the direction of applied lateral pressure as discussed above), that is, door gap gauge  1  is allowed to move in a lateral direction  508 . Door gap gauge  1  is then reoriented, by simply rotating door gap gauge  1  by 90-degrees in a counterclockwise direction about z-axis  9 , and then is inserted such that reference base  5  engages inactive door strike side edge  236 , measuring surface for 3/16″  18  engages active door lock side edge  240 , and a contact surface for 3/16″  41  engages active door face  218  (although engagement is not necessary for device to function correctly). If, while moving door gap gauge  1  in measuring direction  500 , double door gap  244  clearance is less than 3/16-inch, door gap gauge  1  movement will stop. At this location, double door gap  244  clearance is sufficient if the minimum clearance specification for this area has already passed. If, while moving door gap gauge  1  in first measuring direction  500 , double door gap  244  clearance is greater than 3/16-inch, measuring surface for 3/16″  18  will disengage from active door lock side edge  240 , (or reference base  5  will disengage from inactive door strike side edge  236 , depending on the direction of applied lateral pressure), that is, door gap gauge  1  is allowed to move in a lateral direction  508 , indicating a double door gap  244  clearance failure (for metal doors). The double door gap  244  clearance check may continue at other areas along the double door gap  244  in order to further define any other failure areas, if they exist. 
   In another method for checking double door gap  244  clearance, the maximum clearance requirement may be checked first as described above, followed by checking the minimum clearance requirement as described above, that is, the methodology discussed above is performed in reverse order (where door gap gauge  1  is rotated 90-degrees in a clockwise direction about a z-axis  9  when changing from the maximum clearance check to the ⅛″ nominal clearance check to the minimum clearance check, respectively). 
   In the methods discussed above for checking double door gap  244  clearance an alternate method may be implemented by rotating door gap gauge  1  by 180-degrees about y-axis  7 , in either a clockwise or counterclockwise direction, and inserting door gap gauge  1  into double door gap  244 . For this method, first reference base  5  faces active door lock side edge  240 ; measuring surface 1/16″  10 , measuring surface ⅛″  14 , and measuring surface for 3/16″  18  face active door lock side edge  240 , during respective components of the procedure using these measuring surfaces; and contact surface for 1/16″  33 , contact surface for ⅛″  37 , and contact surface for 3/16″  41  engage an inactive door face  206  (although engagement is not necessary for device to function correctly), during respective components of the procedure using these contact surfaces. Clearance checks then proceed as defined above. 
   FIGS.  18  and  19   
   Checking Gaps in Vicinity of Door Hardware 
     FIG. 18  shows a top view of the situation the door gap gauge  1  is used near a door latch  172 . In this figure, door gap gauge  1  is currently checking for the maximum clearance, that is, measuring surface ⅛″  14  is shown positioned in strike jamb gap  176 , although the method applies to minimum clearance checking as well, using appropriate measuring surfaces. In this example, door gap gauge  1  is being moved from the top of a single door  102  toward the bottom of single door  102  in first measuring direction  500  (although door gap gauge  1  could be moved in the other direction, from bottom to top, as well). In this method, as door gap gauge  1  approaches door latch  172 , first connecting surface for ⅛″  34  engages the top surface of door latch  172 . At this location, door gap gauge  1  is pulled outward, perpendicular to single door face  103 , until first connecting surface for ⅛″  34  just disengages from the top surface of door latch  172 . First reference base  5  and measuring surface ⅛″  14  are still positioned within strike jamb gap  176 , and the maximum clearance check continues downward past door latch  172 . Once past door latch  172 , if desired, door gap gauge  1  may be reinserted fully in strike jamb gap  176  until contact surface for ⅛″  37  engages single door face  103 . The maximum clearance check procedure continues as before. 
   In another method door gap gauge  1  may be initially positioned such that first connecting surface for ⅛″  34  never engages the top surface of door latch  172  as door gap gauge  1 , positioned within strike jamb gap  176 , is moved along first measuring direction  500  along the entire length of single door  102 . That is, door gap gauge  1  is not fully inserted in strike jamb gap  176 , but first reference base  5  and measuring surface ⅛″  14  are still positioned within strike jamb gap  176  allowing for clearance checking. 
   Although not shown, in yet another method, door gap gauge  1  can be rotated by 180-degrees about y-axis  7 , in either a clockwise or counterclockwise direction; inserted into strike jamb gap  176 ; and moved along first measuring direction  500 , while avoiding door latch  172 , as discussed just above for measuring minimum or maximum clearance. 
     FIG. 19  shows a top view of the situation when door gap gauge  1  is used near an intumescent smoke seal  254 , which typically is installed along the entire length of a strike jamb  164 , a hinge jamb  136 , and a head jamb  116 . For this example, door gap gauge  1  is currently checking for the maximum clearance, that is, measuring surface ⅛″  14  is shown positioned in strike jamb gap  176 , although the method applies to minimum clearance checking as well, using appropriate measuring surfaces. For this method, door gap gauge  1  is inserted until first connecting surface for ⅛″  34  just engages intumescent smoke seal  254 , while first reference base  5  and measuring surface ⅛″  14  are still positioned within strike jamb gap  176  allowing clearance checking. Clearance checking now proceeds as described in the CHECKING THE STRIKE JAMB GAP section above. The above procedures, although not shown in the figures, apply when other door hardware may be present (such as deadbolts, weather seals, etc.). That is, door gap gauge  1  is capable of gap measurement checking in a variety of situations. 
   Additionally, the above procedures apply to double door gap  244  clearance check where door latch  172 , intumescent smoke seal  254 , or other hardware may be present, such as deadbolts, weather seals, astragals, etc., that is, door gap gauge  1  is capable of gap measurement checking in a variety of situations. 
   FIGS.  20 ,  21 A,  21 B,  21 C, and  21 D 
   Checking the Hinge Side Gap 
   In one method, as shown in  FIGS. 20 and 21A ,  21 B, and  21 C, door gap gauge  1  is being used to check hinge side gap  128  clearance for single door unit  100  made from wood, metal, or other materials. In this method, door gap gauge  1  is used to first check the minimum requirement by utilizing measuring surface 1/16″  10 , as shown in  FIGS. 20 ,  21 A and  21 B, which represents a right hand door configuration. First, door gap gauge  1  is inserted such that first reference base  5  faces a hinge jamb edge  132 , measuring surface 1/16″  10  faces a door hinge side edge  120 , and a contact surface for 1/16″  33  engages single door face  103  (although engagement is not necessary for device to function correctly). If door gap gauge  1  cannot be inserted in this manner, hinge side gap  128  clearance fails since the hinge side gap  128  is less than 1/16-inch wide. If door gap gauge  1  can be inserted in this manner, at any location along hinge side gap  128 , the examination of the minimum hinge side gap  128  clearance continues. Once inserted, lateral pressure is applied such that first reference base  5  is substantially engaged with hinge jamb edge  132  (alternately, lateral pressure could be applied such that measuring surface 1/16″  10  is substantially engaged with door hinge side edge  120 ). While maintaining lateral pressure, door gap gauge  1  is then moved in first measuring direction  500 , which is either in the up direction or the down direction for hinge side gap  128  clearance. If, while moving door gap gauge  1  in first measuring direction  500 , hinge side gap  128  clearance is less than 1/16-inch, door gap gauge  1  movement will stop, indicating a hinge side gap  128  clearance failure. Door gap gauge  1  is removed from hinge side gap  128  at this location and reinserted into hinge side gap  128  (as described above) just past the failed narrow area, and the procedure continues for the minimum clearance check in order to further define any other failure areas, if they exist. If, while moving door gap gauge  1  in first measuring direction  500 , hinge side gap  128  clearance is greater than 1/16-inch, door gap gauge  1  movement will not stop, indicating hinge side gap  128  clearance is adequate for the minimum clearance specification. 
   Once the minimum hinge side gap  128  clearance is checked, door gap gauge  1  is then used to check the maximum requirement for hinge side gap  128  by utilizing measuring surface ⅛″  14 . As seen in  FIG. 21C , door gap gauge  1  is simply rotated by 90-degrees in a counterclockwise direction about z-axis  9 , and then is inserted such that first reference base  5  faces hinge jamb edge  132 , measuring surface ⅛″  14  faces door hinge side edge  120 , and contact surface for ⅛″  37  engages single door face  103  (although engagement is not necessary for device to function correctly). Once inserted, reference base  5  should engage hinge jamb edge  132  and measuring surface ⅛″  14  should engage door hinge side edge  120 , such that door gap gauge  1  cannot move significantly in a lateral direction  508 , while still allowing door gap gauge  1  to move in first measuring direction  500  (shown as going in and out of the drawing in  FIG. 21C ). Once inserted, lateral pressure is applied such that first reference base  5  is substantially engaged with hinge jamb edge  132  (alternately, lateral pressure could be applied such that measuring surface ⅛″  14  is substantially engaged with door hinge side edge  120 ). Door gap gauge  1  is then moved in first measuring direction  500 , which is either in the up direction or the down direction for hinge side gap  128  clearance. If, while moving door gap gauge  1  in first measuring direction  500 , hinge side gap  128  clearance is less than ⅛-inch, door gap gauge  1  movement will stop. At this location, hinge side gap  128  clearance is sufficient if the minimum clearance check for this area has already passed. Door gap gauge  1  is removed from hinge side gap  128  at this location and reinserted into hinge side gap  128  (as discussed above) just past the narrow area, and the procedure continues for the maximum clearance check. If, while moving door gap gauge  1  in first measuring direction  500 , hinge side gap  128  clearance is greater than ⅛-inch, measuring surface ⅛″  14  will disengage from door hinge side edge  120 , (or reference base  5  will disengage from hinge jamb edge  132 , depending on the direction of applied lateral pressure as discussed above), that is, door gap gauge  1  is allowed to move in a lateral direction  508 , indicating a hinge side gap  128  clearance failure. The hinge side gap  128  maximum clearance check may continue at other areas along the hinge side gap  128  in order to further define any other failure areas, if they exist. 
   In another method for checking hinge side gap  128  clearance, the maximum clearance requirement may be checked first as described above, followed by checking the minimum requirement as described above, that is, the methodology discussed above is performed in reverse order (where door gap gauge  1  is rotated 90-degrees in a clockwise direction about a z-axis  9  when changing from the maximum check to the minimum check). 
   Either method discussed above for checking hinge side gap  128  clearance may be implemented in an alternate method by rotating door gap gauge  1  by 180-degrees about y-axis  7 , in either a clockwise or counterclockwise direction, and inserting door gap gauge  1  into hinge side gap  128 .  FIG. 21D  is a top view of a right hand door configuration describing the rotated door gap gauge  1  when used in the maximum clearance. As the rotated door gap gauge  1  is inserted, first reference base  5  faces door hinge side edge  120 , measuring surface ⅛″  14  faces hinge jamb edge  132 , and contact surface for ⅛″  37  engages a hinge jamb face  138  (although engagement is not necessary for device to function correctly). The methods described above for the maximum clearance are then repeated to verify adequate clearance. For the minimum clearance check, door gap gauge  1  is simply rotated by 90-degrees in a clockwise direction about z-axis  9 , and then is inserted such that first reference base  5  faces door hinge side edge  120 , measuring surface 1/16″  10  faces hinge jamb edge  132 , and contact surface for 1/16″  33  engages hinge jamb face  138  (although engagement is not necessary for device to function correctly). The methods described above for the minimum clearance are then repeated to verify adequate clearance. 
   Hinge side gap  128  clearances for the double door unit  200  are checked identically as described above for single door unit  100 , where single door  102  components are replaced by an active door  216  components and an inactive door  204  components, respectively, where applicable. 
   Measuring hinge side gap  128  clearance when other door hardware may be present, such as weather seals, intumescent seals, etc., for either the single door unit  100  or the double door unit  200 , is performed in a similar manner as described above in CHECKING GAPS IN VICINITY OF DOOR HARDWARE, where references to door strike side and strike jamb are replaced by references to door hinge side and hinge jamb, respectively, where applicable. 
   FIG.  22 A,  22 B,  22 C,  22 D and  22 E 
   Checking the Top Gap 
   In one method, as shown in  FIGS. 22A ,  22 B,  22 C,  22 D, and  22 E, door gap gauge  1  is being used to check top gap  108  clearance for single door unit  100  made from wood, metal, or other materials. Door gap gauge  1  is used to first check the minimum clearance requirement by utilizing measuring surface 1/16″  10 , as shown in  FIGS. 22A and 22B . First, door gap gauge  1  is inserted such that first reference base  5  faces a head jamb edge  112 , measuring surface 1/16″  10  faces a door top edge  104 , and contact surface for 1/16″  33  engages single door face  103  (although engagement is not necessary for device to function correctly). If door gap gauge  1  cannot be inserted in this manner, top gap  108  clearance fails since the top gap  108  is less than 1/16-inch wide. If door gap gauge  1  can be inserted in this manner, at any location along top gap  108 , the examination of the minimum top gap  108  clearance continues. Once inserted, lateral pressure is applied such that first reference base  5  is substantially engaged with head jamb edge  112  (alternately, lateral pressure could be applied such that measuring surface 1/16″  10  is substantially engaged with door top edge  104 ). While maintaining lateral pressure, door gap gauge  1  is then moved in a second measuring direction  504 , which is either in the right or left direction for top gap  108  clearance (shown as going in and out of the drawing in  FIG. 22B ). If, while moving door gap gauge  1  in second measuring direction  504 , top gap  108  clearance is less than 1/16-inch, door gap gauge  1  movement will stop, indicating a top gap  108  clearance failure. Door gap gauge  1  is removed from top gap  108  at this location and reinserted into top gap  108  (as described above) just past the failed narrow area, and the procedure continues for the minimum clearance check in order to further define any other failure areas, if they exist. If, while moving door gap gauge  1  in second measuring direction  504 , top gap  108  clearance is greater than 1/16-inch, door gap gauge  1  movement will not stop, indicating top gap  108  clearance is adequate for the minimum clearance specification. 
   Once the minimum top gap  108  clearance is checked, door gap gauge  1  is then used to check the maximum clearance requirement for top gap  108  by utilizing measuring surface ⅛″  14 . As seen in  FIG. 22C , door gap gauge  1  is simply rotated by 90-degrees in a counterclockwise direction about z-axis  9 , and then is inserted such that first reference base  5  faces head jamb edge  112 , measuring surface ⅛″  14  faces door top edge  104 , and a contact surface for ⅛″  37  engages single door face  103  (although engagement is not necessary for device to function correctly). Once inserted, reference base  5  should engage head jamb edge  112  and measuring surface ⅛″  14  should engage door top edge  104 , such that door gap gauge  1  cannot move significantly in a lateral direction  508 , while still allowing door gap gauge  1  to move in second measuring direction  504 . Once inserted, lateral pressure is applied such that first reference base  5  is substantially engaged with head jamb edge  112  (alternately, lateral pressure could be applied such that measuring surface ⅛″  14  is substantially engaged with door top edge  104 ). Door gap gauge  1  is then moved in second measuring direction  504 , which is either in the right or left direction for top gap  108  clearance. If, while moving door gap gauge  1  in second measuring direction  504 , top gap  108  clearance is less than ⅛-inch, door gap gauge  1  movement will stop. At this location, top gap  108  clearance is sufficient if the minimum clearance check for this area has already passed. Door gap gauge  1  is removed from top gap  108  at this location and reinserted into top gap  108  (as discussed above) just past the narrow area, and the procedure continues for the maximum clearance check. If, while moving door gap gauge  1  in second measuring direction  504 , top gap  108  clearance is greater than ⅛-inch, measuring surface ⅛″  14  will disengage from door top edge  104 , (or reference base  5  will disengage from head jamb edge  112 , depending on the direction of applied lateral pressure as discussed above), that is, door gap gauge  1  is allowed to move in a lateral direction  508 , indicating a top gap  108  clearance failure. The top gap  108  maximum clearance check may continue at other areas along the top gap  108  in order to further define any other failure areas, if they exist. 
   In another method for checking top gap  108  clearance, the maximum requirement may be checked first as described above, followed by checking the minimum requirement as described above, that is, the methodology discussed above is performed in reverse order (where door gap gauge  1  is rotated 90-degrees in a clockwise direction about a z-axis  9  when changing from the maximum check to the minimum check). 
   Either method discussed above for checking top gap  108  clearance may be implemented in an alternate method by rotating door gap gauge  1  by 180-degrees about y-axis  7 , in either a clockwise or counterclockwise direction, and inserting door gap gauge  1  into top gap  108 .  FIG. 22D  describes the rotated door gap gauge  1  when used in the minimum clearance check. As the rotated door gap  1  is inserted, first reference base  5  faces door top edge  104 , measuring surface 1/16″  10  faces head jamb edge  112 , and a contact surface for 1/16″  33  engages head jamb face  114  (although engagement is not necessary for device to function correctly). The methods described above for the minimum clearance check are then repeated to verify adequate clearance. For the maximum clearance check, as shown in  FIG. 22E , door gap gauge  1  is simply rotated by 90-degrees in a counterclockwise direction about z-axis  9 , and then is inserted such that first reference base  5  faces door top edge  104 , measuring surface ⅛″  14  faces head jamb edge  112 , and a contact surface for ⅛″  37  engages head jamb face  114  (although engagement is not necessary for device to function correctly). The methods described above for the maximum clearance are then repeated to verify adequate clearance. 
   Top gap  108  clearances for the double door unit  200  are checked in a similar manner as described above for single door unit  100 , where single door  102  is replaced by active door  216  and inactive door  204 , respectively, where applicable. 
   Measuring top gap  108  clearance when other door hardware may be present, such as flush bolts, weather seals, intumescent seals, etc., for either the single door unit  100  or the double door unit  200 , is performed in a similar manner as described above in CHECKING GAPS IN VICINITY OF DOOR HARDWARE, where references to door strike side and strike jamb are replaced by references to door top and head jamb, respectively, where applicable. 
   FIGS.  23 ,  24 ,  25 , and  26   
   Checking the Bottom Gap 
   In one method, as shown in  FIGS. 23 and 24 , door gap gauge  1  is being used to check bottom gap  148  clearance for single door unit  100  and double door unit  200  when noncombustible floor surface  140  is present. The following description uses the single door unit  100  to describe the procedure, however, bottom gap  148  clearances for the double door unit  200  are checked in a similar manner, where single door  102  components are replaced by active door  216  components and inactive door  204  components, respectively, where applicable. 
   Door gap gauge  1  is used to check the clearance requirement by utilizing measuring surface for ¾″  24 . Door gap gauge  1  is inserted such that second reference base  8  faces noncombustible floor surface  140 , measuring surface for ¾″  24  faces a door bottom edge  144 , and connecting surface two for ⅜″  48  engages single door face  103  (although engagement is not necessary for device to function correctly). If door gap gauge  1  cannot be inserted in this manner, bottom gap  148  clearance passes, since bottom gap  148  is less than ¾-inch wide. Once inserted, second reference base  8  should engage noncombustible floor surface  140  and measuring surface for ¾″  24  should engage door bottom edge  144 , such that door gap gauge  1  cannot move significantly in lateral direction  508 , while still allowing door gap gauge  1  to move in second measuring direction  504  (shown as going in and out of the drawing in  FIG. 24 ). Once inserted, lateral pressure is then applied such that second reference base  8  is substantially engaged with noncombustible floor surface  140  (alternately, lateral pressure could be applied such that measuring surface for ¾″  24  is substantially engaged with door bottom edge  144 ). Door gap gauge  1  is then moved in second measuring direction  504 , which is either in the right or left direction for bottom gap  148  clearance. If, while moving door gap gauge  1  in second measuring direction  504 , bottom gap  148  clearance is less than ¾-inch, door gap gauge  1  movement will stop. At this location, bottom gap  148  clearance is sufficient and bottom gap  148  clearance passes. Door gap gauge  1  is removed from bottom gap  148  at this location and reinserted into bottom gap  148  (as described above) just past the narrow area, and the procedure continues for the bottom gap  148  clearance check. If, while moving door gap gauge  1  in second measuring direction  504 , bottom gap  148  clearance is greater than ¾-inch, measuring surface for ¾″  24  will disengage from door bottom edge  144 , (or second reference base  8  will disengage from noncombustible floor surface  140 , depending on the direction of applied lateral pressure), that is, door gap gauge  1  is allowed to move in a lateral direction  508 , indicating a bottom gap  148  clearance failure. The bottom gap  148  clearance check may continue at other areas along the bottom gap  148  in order to further define any other failure areas, if they exist. 
   In another method, as shown in  FIG. 25 , door gap gauge  1  is being used to check bottom gap  148  clearance for single door unit  100  and double door unit  200 , when combustible floor surface  142  is present and threshold-sill unit  152  is installed. The following description uses the single door unit  100  to describe the procedure, however, bottom gap  148  clearances for the double door unit  200  are checked in a similar manner, where single door  102  components are replaced by active door  216  components and inactive door  204  components, respectively, where applicable. 
   Door gap gauge  1  is used to check the clearance requirement by utilizing measuring surface for ⅜″  26 . Door gap gauge  1  is inserted such that first reference base  5  faces a sill top surface  153 , and measuring surface for ⅜″  26  faces door bottom edge  144 . If door gap gauge  1  cannot be inserted in this manner, bottom gap  148  clearance passes, since bottom gap  148  is less than ⅜-inch wide with threshold-sill unit  152  installed. Once inserted, first reference base  5  should engage sill top surface  153  and measuring surface ⅜″  26  should engage door bottom edge  144 , such that door gap gauge  1  cannot move significantly in lateral direction  508 , while still allowing door gap gauge  1  to move in second measuring direction  504  (shown as going in and out of the drawing in  FIG. 25 ). Once inserted, lateral pressure is applied such that first reference base  5  is substantially engaged with sill top surface  153  (alternately, lateral pressure could be applied such that measuring surface ⅜″  26  is substantially engaged with door bottom edge  144 ). Door gap gauge  1  is then moved in second measuring direction  504 , which is either in the right or left direction for bottom gap  148  clearance. If, while moving door gap gauge  1  in second measuring direction  504 , bottom gap  148  clearance is less than ⅜-inch, door gap gauge  1  movement will stop. At this location, bottom gap  148  clearance is sufficient and bottom gap  148  clearance passes. Door gap gauge  1  is removed from bottom gap  148  at this location and reinserted into bottom gap  148  (as discussed above) just past the narrow area, and the procedure continues for the bottom gap  148  clearance check. If, while moving door gap gauge  1  in second measuring direction  504 , bottom gap  148  clearance is greater than ⅜-inch, measuring surface for ⅜″  26  will disengage from door bottom edge  144 , (or first reference base  5  will disengage from sill top surface  153 , depending on the direction of applied lateral pressure as discussed above), that is, door gap gauge  1  is allowed to move in a lateral direction  508 , indicating a bottom gap  148  clearance failure. The bottom gap  148  clearance check may continue at other areas along the bottom gap  148  in order to further define any other failure areas, if they exist. 
   In the method discussed above for checking ⅜-inch clearance, bottom gap  148  clearance may be implemented in an alternate method by rotating door gap gauge  1  by 180-degrees about an x-axis  6 , in either a clockwise or counterclockwise direction, and then inserting rotated door gap gauge  1  into bottom gap  148 . As door gap  1  is inserted, first reference base  5  faces door bottom edge  144  and measuring surface for ⅜″  26  faces sill top surface  153 . The method described above for checking ⅜-inch clearance is then repeated to verify adequate clearance for both single door unit  100  or double door unit  200 . 
   In yet another method, as shown in  FIG. 26 , door gap gauge  1  is being used to check bottom gap  148  clearance for single door unit  100  and double door unit  200 , when combustible floor surface  142  is present, threshold-sill unit  152  is installed (considering a typical ½-inch high threshold-sill unit  152 ), and changes in level (height) must meet ADA regulations (note that a ¼-inch or ⅜-inch high threshold-sill unit  152  would pass ADA standards at which point door gap gauge  1  is used to check bottom gap  148  clearance requirement by utilizing measuring surface for ⅜″  26  as discussed above). The following description uses inactive door  204  components to describe the procedure, however, bottom gap  148  clearances for active door  216 , and single door unit  100 , are checked in a similar manner, where inactive door  204  components are replaced by active door  216  components, and single door  100  components, respectively, where applicable. 
   Door gap gauge  1  is used to check the clearance requirement by utilizing measuring surface for ¼″  22 . Door gap gauge  1  is inserted such that first reference base  5  faces sill top surface  153 , and measuring surface for ¼″  22  faces an inactive door bottom edge  228 . If door gap gauge  1  cannot be inserted in this manner, bottom gap  148  clearance passes, since bottom gap  148  is less than ¼-inch wide (indicating that overall bottom gap  148  is ¾-inch or less). If door gap gauge  1  can be inserted in this manner, at any location along bottom gap  148 , the examination of the bottom gap  148  clearance continues. 
   Once inserted, first reference base  5  should engage sill top surface  153  and measuring surface ¼″  22  should engage inactive door bottom edge  228 , such that door gap gauge  1  cannot move significantly in a lateral direction  508 , while still allowing door gap gauge  1  to move in second measuring direction  504  (shown as going in and out of the drawing in  FIG. 26 ). Once inserted, lateral pressure is applied such that first reference base  5  is substantially engaged with sill top surface  153  (alternately, lateral pressure could be applied such that measuring surface ¼″  22  is substantially engaged with inactive door bottom edge  228 ). Door gap gauge  1  is then moved in second measuring direction  504 , which is either in the right or left direction for bottom gap  148  clearance. If, while moving door gap gauge  1  in second measuring direction  504 , bottom gap  148  clearance is less than ¼-inch, door gap gauge  1  movement will stop. At this location, bottom gap  148  clearance is sufficient. Door gap gauge  1  is removed from bottom gap  148  at this location and reinserted into bottom gap  148  just past the narrow area (as discussed just above), and the procedure continues. If, while moving door gap gauge  1  in second measuring direction  504 , bottom gap  148  clearance is greater than ¼-inch, measuring surface ¼″  22  will disengage from inactive door bottom edge  228 , (or reference base  5  will disengage from sill top surface  153 , depending on the direction of applied lateral pressure as discussed above), that is, door gap gauge  1  is allowed to move in a lateral direction  508 , indicating a bottom gap  148  clearance failure. The bottom gap  148  clearance check may continue at other areas along the bottom gap  148  in order to further define any other failure areas, if they exist. 
   In the method discussed above for checking ¼-inch clearance, bottom gap  148  clearance may be implemented in an additional method by rotating door gap gauge  1  by 180-degrees about y-axis  7 , in either a clockwise or counterclockwise direction, and then inserting door gap gauge  1  into bottom gap  148 . As door gap  1  is inserted, first reference base  5  faces door bottom edge  144  and measuring surface for ¼″  22  faces sill top surface  153 . The method described above for checking ¼-inch clearance is then repeated to verify adequate clearance. 
   FIG.  27   
   Checking the Bottom Gap in Vicinity of Door Hardware 
     FIG. 27  shows a side view of an application when the door gap gauge  1  is used to check bottom gap  148  clearance near door hardware, which may include flush bolts, weather stripping, bottom brushes, or automatic door bottoms, to name a few. In this particular example a flush bolt  258 , which may be used to secure inactive door  204  in a double door unit  200 , is shown. For this example, door gap gauge  1  is used to check for a ¾-inch clearance since noncombustible floor surface  140  is present. When door gap gauge  1  is inserted, second reference base  8  engages noncombustible floor surface  140  and measuring surface for ¾″  24  engages inactive door bottom edge  228 , such that door gap gauge  1  cannot move significantly in lateral direction  508 , while still allowing door gap gauge  1  to move in second measuring direction  504  (shown as going in and out of the drawing in  FIG. 27 ), as discussed above for bottom gap clearance. Door gap gauge  1  is being moved from the right to the left along inactive door  204  in second measuring direction  504  (although door gap gauge  1  could be moved in the other direction, from left to right, as well). In this alternate method, as door gap gauge  1  approaches flush bolt  258 , surface  22  may engage flush bolt  258 . At this location, door gap gauge  1  is pulled outward, perpendicular to inactive door face  206 , until surface  22  just disengages from flush bolt  258  (as shown in  FIG. 27 ). Second reference base  8  and measuring surface ¾″  24  are still positioned within bottom gap  148 , and the clearance check continues past flush bolt  258 , as discussed above for bottom gap clearance. Once door gap gauge  1  has moved past flush bolt  258 , door gap gauge  1  may be inserted fully in bottom gap  148  until surface  48  engages inactive door face  206 . The clearance check procedure then continues as before, as discussed above for bottom gap clearance. 
   In yet another method door gap gauge  1  may be initially positioned such that surface  22  never engages flush bolt  258  as door gap gauge  1  is moved along second measuring direction  504  along the entire length of inactive door  204  within bottom gap  148 , as described in  FIG. 27 . That is, door gap gauge  1  is not fully inserted in bottom gap  148 , but second reference base  8  and measuring surface ¾″  24  are still positioned within bottom gap  148 , allowing for clearance checking, as discussed above for bottom gap clearance. 
   The above procedures also apply to bottom gap  148  clearance for active door  216 , and single door unit  100 , when other door hardware, such as weather stripping, bottom brushes, or automatic door bottoms, to name a few, may be present. 
   Additionally, the above procedures, pertaining to other door hardware, apply to situations when combustible floor surface  142  is present and threshold-sill unit  152  is installed. That is, door gap gauge  1  is capable of checking bottom gap measurement in a variety of situations. 
   FIGS.  8 ,  9 A and  9 B 
   Checking Gaps Using Tactile Locator Markers 
   In yet another method, door gap gauge  300 , with plurality of tactile locator marker groups  302 ,  304 ,  308 ,  312 ,  316 , and  320 , is used for quick and accurate determination of building code compliance for all gap openings related to door installations. In this method, the door gap gauge user may position door gap gauge  1  to the desired gap clearance measurement orientation by utilizing the finger&#39;s sense of touch to feel the shape and number of tactile locator marker groups  302 ,  304 ,  308 ,  312 ,  316 , and  320 , which in turn indicate which measuring surface is being used. Each tactile locator marker group includes a tactile directional marker  324  and a subgroup of gap measurement marker indicators  330 ,  334 ,  338 ,  342 ,  346 , and  350 , indicating measurements 1/16″, ⅛″, 3/16″, ¼″, ⅜″, and ¾″, respectively. 
   As an example, shown in  FIG. 8 , in order to check the ⅛-inch clearance, door gap gauge user would hold door gap gauge  1  such that the user&#39;s thumb would align in a tactile directional locator direction  326  over tactile locator marker group for ⅛″  304 . The user&#39;s thumb would physically sense tactile locator marker subgroup for ⅛″  330  and tactile directional locator  324 , which is located just behind subgroup  330  along tactile directional locator direction  326 . If the user does not sense tactile directional locator  324  just behind subgroup  330 , door gap gauge  300  is not correctly oriented for the ⅛-inch gap clearance. Clearance checking for all ⅛″ gaps is then performed identically to those methods presented above. This tactile method is repeated in a similar manner for all gap measurement surfaces. 
   From the foregoing, it is apparent that the door gap gauge described above not only provides for the reliable accomplishment of the purpose of the invention, but does so in a particularly simple, quick and reliable manner. It is recognized, of course, that those skilled in the art may make various modifications or additions to the exemplary embodiments chosen to illustrate the invention without departing from the spirit and scope of the present contribution to the art. Accordingly, it is to be understood that the protection sought and to be afforded hereby should be deemed to extend to the subject matter claimed and all equivalents thereof within the scope of the invention.