A building structure comprises a post having a vertically extending longitudinal face. A plurality of horizontal logs extends from said longitudinal face and has an end face in abutment with said longitudinal face. The post having an undercut channel in said longitudinal face and extends along said post. At least one of said end faces has a recess aligned with said undercut channel, and a spline assembly extends between said post and said log to secure said log to said post. The spline assembly includes a key located in and extends between said channel and said recess and an insert in one of said undercut channel and said recess. The insert co operates with said key to facilitate relative sliding movement therebetween.

BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates generally to wall structures and in particular to wall structures for post-and-log construction. 
         [0002]    Log construction has been known for many decades as typified by the log cabin. For many years the logs have been notched so that at a corner logs forming one wall of a structure can be laid on top of and at an angle alternating with logs from an intersecting wall. In practical use, such construction is usually limited to right angle corners because of the complexity of the angled notches required for non-right angle corners. More recently, posts have been introduced that can be milled with longitudinal faces at a range of desirable angles such that wall members having square-cut ends can be attached by spikes to the posts to form right-angle or non-right angle corners. Although a number of materials may be used to form the “logs” used as wall members, including various types of composite materials, the wall members are typically milled from wood. The term “logs” will be used throughout this disclosure to include all types of materials that simulate a horizontal wooden log and includes different cross sections, either machined, hand-hewn or in a natural state. 
         [0003]    To form a tight connection between die logs and the posts, split key members have been used that engage cooperating undercut recesses in the end of the log and a face of the post. In U.S. Pat. No. 6,050,033 there is disclosed a spline arrangement in which the log and post are connected by a key formed by a pair of wedges. The key is expandable and secured the log to the post. A first section of the key member is fitted into place to engage the recesses in the post and the log and then a second section of the key member is inserted and tapped into place beside the first section of the key member. The cross-sections of the split key member are wedge-shaped and tighten the joint as the second portion of the key member is tapped into place. 
         [0004]    It is necessary to ensure that the interconnecting butt joints are tight and provide an effective seal, but at the same time accommodate relative movement between logs whilst maintaining a seal. This is particularly an issue in wooden log construction because of the shrinkage of the logs as they dry. This causes the logs to settle and move vertically down. However, in some circumstances the connection of the key to both the log and the post as shown in U.S. Pat. No. 6,050,033 may inhibit such movement and as a result a gap is created between adjacent logs in the log walls. 
         [0005]    It is an object of the present invention to obviate or mitigate the above disadvantages. 
       SUMMARY OF THE INVENTION 
       [0006]    According to one aspect of the invention, a building structure comprises a post having a vertically extending longitudinal face, a plurality of horizontal logs extending from said longitudinal face and having an end face in abutment with the longitudinal face. The post has an undercut channel in the longitudinal face and extends along the post. At least one of the end faces has a recess aligned with the undercut channel and a spline assembly extends between the post and the log to secure the log to the post. The spline assembly includes a key located in and extending between the undercut channel and the recess and a key slide in one of the undercut channel and the recess. The key slide co operates with the key to facilitate relative sliding movement of the logs and the post. 
         [0007]    A further aspect of the invention provides a spline assembly to secure a log to a post in building, said spline assembly including a key slide for insertion into an undercut channel in said post and a key for insertion into said key slide and a recess in said log to extend between said log and inhibit separation thereof. 
         [0008]    A still further aspect of the invention provides a method of assembling a log to a post comprising the steps of providing an undercut channel in a longitudinal face of the post, inserting in the undercut channel providing a recess in the log, aligning the recess with the key slide undercut channel, inserting a key into the key slide to extend between the post and the log, and securing the key to the recess, whereby relative movement between the log and the post is accommodated by relative sliding movement between the key slide and the key. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The principles of the various aspects of the invention may better be understood by reference to the accompanying illustrative drawings which depict features of examples of embodiments of the invention, and in which: 
           [0010]      FIG. 1  is a perspective view of a building. 
           [0011]      FIG. 2  is a view on the line II-II of  FIG. 1  showing components as assembled. 
           [0012]      FIG. 3  is a view similar to  FIG. 2  with the components in a locked condition. 
           [0013]      FIG. 4  is an exploded view of the components shown in  FIG. 3 . 
           [0014]      FIG. 5  is a perspective view of a key member used in the embodiment of  FIGS. 1 to 4 . 
           [0015]      FIG. 6  is a rear perspective of the key member of  FIG. 5 . 
           [0016]      FIG. 7(   a )-( k ) is a schematic representation of the steps of assembling the building of  FIG. 1 . 
           [0017]      FIG. 8  is an exploded view of components used in the building of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    The description that follows and the embodiments described therein are provided by way of illustration of examples of particular embodiments of the principles of the present invention. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the invention. In the description, like parts are marked throughout the specification and the drawings with the same respective reference numerals. 
         [0019]    The drawings are not necessarily to scale and in some instances proportions may have been exaggerated in order more clearly to depict certain features of the invention. 
         [0020]    Referring therefore to  FIG. 1 , a building  1  includes a pair of log walls  2  that intersect at a post  10 . The log walls  2  are supported on a foundation wall  3 , that may be poured concrete or laid block, and have openings for windows  4 . The log walls  2  will support a roof or additional framed storey in a conventional manner. The log walls  2  are formed from horizontal logs  11  that are laid horizontally one on top of the other and are secured to the corner post  10  to form an integral structure. 
         [0021]    Each of the logs  11  is machined to a uniform cross section and have complementary tongues and grooves formed on abutting faces, upper and lower faces  13   a ,  13   b  ( FIG. 4 ). A sealant, typically in the form of a mastic tape, is located between the tongue and groove and compressed by the log to form an effective seal. The particular form of tongue and groove forms no part of the present invention and a variety of configurations may be used, such as that shown in U.S. Pat. No. 5,020,289. 
         [0022]    It will be appreciated that the log walls  2  extend around the periphery of the building  1  and the logs  11  are cut to the required length to conform to the desired floor plan. 
         [0023]    The post  10  extends vertically the height of the wall  2  and each post  10  has a pair of generally planar faces  12 ,  14 , that are disposed at an included angle corresponding to the corner of the building  1 . Typically, the faces  12 ,  14  intersect at right angles but other included angles can be provided, as shown in  FIG. 7 . 
         [0024]    As can best be seen in  FIG. 2 , each of the logs  11  has an end face  16  that extends between the upper and lower faces  13   a ,  13   b  to butt against one of the faces  12 ,  14  of the post  10 . The end face  16  has a part cylindrical slot  17  extending between the upper and lower faces  13   a ,  13   b  of the log  11  and intersecting the end face  16  so as to define a re-entrant recess in the end face  16 . 
         [0025]    Sealant slots  18  are provided along the length of each of the faces  12 ,  14  of post  10 . The sealant slots  18  are dimensioned to accept sealant materials, typically in the form of butyl or impregnated foam tapes  19  that are exposed to the end face  16  when a log  11  is butted against post  10 . 
         [0026]    Each of the faces  12 ,  14  has an undercut channel  20  extending along the length of the post  10 . The undercut channel  20  has a parallel sided body portion  22  which opens to an enlarged socket  24 . Inclined flanks  26  connect the body portion  22  to the enlarged socket  24 . The width of the body portion  22  corresponds to that of the part cylindrical slot  17  at the end face  16 . 
         [0027]    The logs  11  are held against the respective face  12 ,  14  by the spline assembly generally indicated at  30  in  FIG. 4 . The spline assembly  30  includes a key  32  and a key slide  70 . The key  32  has a pair of key members  32   a ,  32   b  that are identical to one another and have a length slightly less than the corresponding height of the log  11 . For example, with a log of nominal 12″ height, the key  32  will typically be 10″ in length. 
         [0028]    The key members  32   a ,  32   b  are best seen in  FIGS. 5 and 6 . Each key member  32   a ,  32   b  is molded from a plastics material and has an outer shell  34  with a hollow interior  36  with reinforcing ribs  38  integrally molded with the outer shell  34 . In cross section, each of the key members  32   a ,  32   b  is similar to one half of the void formed between the part cylindrical slot  17 , undercut channel  20  and they key slide  70  so that a pair of key members  32   a ,  32   b  may be inserted within the void. 
         [0029]    Each of the key members  32   a ,  32   b  has an enlarged head  40  connected by a neck  42  to a flared shoulder  44 . The enlarged head  40  has an arcuate undersurface  46  terminating in radial step  48 . Each end of the key members  32   a ,  32   b  has a tapered terminal section  50  on the neck  42  and the flared shoulder  44  to facilitate insertion in to the key slide  70 . End walls  52  enclose the shell at each end up to a median plane  54 . A flange  56  projects outwardly from the median plane  54  at one end and extends one half the length of the key member  32   a ,  32   b . A slot  58  having a depth slightly greater than that of the flange  56  is molded into the key member  32   a ,  32   b  in alignment with the flange  56  over the balance of the length of the key member  32   a ,  32   b . A notch  59  is formed in each end wall  52  beside the flange  56  and slot  58  respectively. 
         [0030]    The flange  56  and slot  58  are arranged such that when two key members  32   a ,  32   b  are placed back to back, the flange  56  of one is received in the slot  58  of the other, so a continuous barrier is provided along the length of the key members  32   a ,  32   b . It will be noted from  FIG. 5  that the arcuate undersurface  46  has embossments  60  molded along its length. The embossments  60  are in the form of letters in the embodiment shown that project slightly above the undersurface  46 . Similar embossments  62 ,  64  are molded on the neck  42  and above the radial step  48 . 
         [0031]    As can best be seen in FIGS.  2 , 4  and  8 , the key slide  70  of the spline assembly  30  is an elongate channel member arranged to be a sliding fit within the enlarged socket  24  of the undercut channel  20 . The key slide  70  extends the full height of the post  10  as a continuous member and is inserted into the enlarged socket  24  of undercut channel  20  after machining of the post  10 . The key slide  70  is dimensioned to have contact with the parallel sided body portion  22  of the undercut channel  20 , inclined flanks  26  and enlarged socket  24  in its free body state so as to be retained within the undercut channel  20  during transport of the post  10  and subsequent assembly of the log walls  2  and the post  10 . 
         [0032]    As can best be seen in  FIGS. 2 ,  3  and  8 , the key slide  70  has an outer surface that conforms substantially to the enlarged socket  24 . The key slide  70  has a throat  74  that extends into the body portion  22  with the inwardly directed surfaces of the throat  74  radiussed so as to provide a rolling contact between the junction of the neck  42  and the flared shoulder  44  of each of the key members  32   a ,  32   b . The key slide  70  is of substantially uniform thickness so as to be a snug sliding fit within the enlarged socket  24  and allow the neck  42  and flared shoulder  44  of key  32  to be a sliding fit within the key slide  70 . 
         [0033]    The key slide  70  is formed of a suitable material having the requisite thermal insulation qualities, low surface friction, hardness and durability. A thermo-plastic material such as polyethylene or polypropylene is suitable. Polypropylene has a relatively low surface friction to facilitate insertion and to provide a smooth sliding surface between the key  32  and the key slide  70 . 
         [0034]    The assembly of the log walls  2  shown in  FIG. 1  is best seen with reference to the sequence represented in  FIG. 7 . Initially, a flashing F is secured to the foundation wall  3  and two rows of butyl tape  80  are applied toward the exterior of the building. The paper covering found on the butyl tape is left in situ to allow for slight adjustment of the initial course of logs  11 . 
         [0035]    With the two rows of butyl tape  80  installed on the flashing F, the post  10  is placed on the foundation wall  3  and foam tape  19  inserted into each of the sealant slots  18  on one face  12  of the post  10  ( FIG. 7   b ). The surface of the foam tape  19  immediately adjacent the work area is revealed by removal of the paper covering, which progresses along the length of the post  10  as the log wall  2  is assembled. 
         [0036]    The initial log II is then placed against the post  10  with the end face  16  in abutment with the face  12  ( FIG. 7   c ). In this position, the part cylindrical slot  17  is aligned with the undercut channel  20 . An asphalt impregnated foam pad  82  conforming to the shape of the part cylindrical slot  17  and undercut channel  20  is inserted from the top of the log  11  ( FIG. 7   d ) and pushed down in the part cylindrical slot  17  until it reaches the top of the foundation wall  3 . 
         [0037]    To secure the log II to the post  10 , a key  32  is inserted, as shown in  FIGS. 7   e  to  7   g . Prior to insertion of the key  32  lengths of sealant tape  84 ,  86  are applied to the neck  42  directly on embossment  62  and to the enlarged head  40  directly on embossment  64  of each key member  32   a ,  32   b . These locations are not initially in engagement with the parallel sided body portion  22  or the part cylindrical slot  17  during insertion and the sealant tape therefore remains in situ during insertion of the key  32 . The sealant tape  84 ,  86  is held in situ during insertion by the inherent adhesiveness of the exposed surface of the sealant tape  84 , 86  and by engagement with the embossments  62 , 64  molded on the surface of the outer shell  34 . When initially placed on the key member  32   a ,  32   b , the sealant tape  84 ,  86  is in a compressed state as it has been removed from a roll of tape and progressively expands to its free body form. Each of the key members  32   a ,  32   b  is inserted into the key slide  70  individually such that the flared shoulder  44  may pass through the throat  74  of the key slide  70  ( FIGS. 7   e  and  7   f ). The key member  32   a  is inserted with the flange  56  lower most. The key member  32   b  may then be inserted into the key slide  70  above the key member  32   a  and the two key members  32   a ,  32   b  slid together axially. The flange  56  on one key member  32   a  is received in the slot  58  of the other key member  32   b  as the key members  32   a ,  32   b  slide together to form the key  32 . 
         [0038]    With the key members  32   a ,  32   b  assembled, they form the key  32  and may be pushed as a unit into the part cylindrical slot  17  ( FIG. 7   g ) until they are flush with the bottom of the grooves provided in the top surface  13   a  of the log  11 . At this time, the sealant  84 ,  86  has not expanded to its free body state, thereby avoiding contact with the walls of the part cylindrical slot  17  or parallel sided body portion  22  of the undercut channel  20 . The key members  32   a ,  32   b  and key slide  70  are dimensioned such that the key  32  may slide relatively easily along the key slide  70  and into the part cylindrical slot  17 . Typically a clearance in the order of ⅛ of an inch on the diameter is provided between the arcuate undersurface  46  and the cylindrical wall of the part cylindrical slot  17 . However, the flared shoulders  44  extend laterally into key slide  70  within the enlarged socket  24  so as to inhibit removal of the key  32 . With the key  32  correctly positioned, the key members  32   a ,  32   b  are forced apart within the part cylindrical slot  17  by insertion of a spike  88  along the length of the key member  32   a ,  32   b  ( FIG. 7   h ). The spike  88  is inserted into the notch  59  provided adjacent the flange  56  and acts as a wedge to separate the key members  32   a ,  32   b . The enlarged head  40  is dimensioned to prevent removal from the part cylindrical slot  17  in the locked condition as seen in  FIG. 3 . The flanges  56  act as a barrier to prevent lateral movement of the spike  88  from between the key members  32   a ,  32   b  and to cause a uniform spreading of the key  32  within the part cylindrical slot  17 . The relatively small surface area of the reinforcing ribs  38  reduces the friction on the spike  88  and reduces the downward force transferred to the key members  32  by the spike  88 . The initial expansion of the key members  32  also brings the embossments  60  in to engagement with the walls of part cylindrical slot  17  to inhibit further downward movement. 
         [0039]    The spike  88  separates the key members  32   a ,  32   b  within the part cylindrical slot  17  but the inner edges of the flared shoulders  44  within the key slide  70  remain in contact with one another. As can be seen from a comparison between  FIGS. 2 and 3 , spreading of the key members  32   a ,  32   b  causes a rolling action about the curved surfaces of the throat  74  of the slide so as to provide essentially an outward force that is readily resisted by the material in the post  10 , as opposed to a torque acting so as to break off the material at the body portion  22  of the undercut channel  20 . At the same time, the sealant tape  84 ,  86  are compressed against the enlarged head  40  and part cylindrical slot  17  as well as the neck  42  and undercut channel  20  to provide a continuous uniform seal within the undercut channel  20  and part cylindrical slot  17  respectively. The spreading of the key members  32   a ,  32   b  as shown in  FIG. 3  causes the log  11  to be drawn tightly against the face of the post  10  causing the foam tape  19  in sealant slots  18  to be similarly compressed to form a continuous seal. An asphalt impregnated foam pad  90  is then inserted onto the top of the key  32  to ensure a proper seal between adjacent key  32  ( FIG. 7   i ). However, the reduced spreading within the key slide  70  in combination with the low friction material of the key slide facilitates sliding movement of the key  32  along the key slide  70 . 
         [0040]    With the initial log in situ, a similar procedure is followed with the log on the opposite face  12  of the post  10  to provide the first row of logs  11  ( FIGS. 7   j - 7   k ). The upper surface  13   a  of the log  11  is then prepared by applying sealant strips  92  to the seal grooves on the upper surface of each log II and the next log  11  placed in position. The key  32  is then inserted as described above and the process continues up each side of the post  10  until the full height of the log wall  2  has been attained. 
         [0041]    During assembly, the weight of each of the logs  11  is sufficient to induce sliding between the key  32  and the key slide  70  to accommodate downward vertical sliding movement of the logs and compression of the sealant strips  92 . Optionally, a bolt may be inserted vertically through the log walls  2  and tensioned to force the logs  11  together. As the logs dry, the weight of the logs  11  and the tension in the thru bolt if used, is sufficient to force the key  32  to slide within the key slide  70  and maintain a sealed relationship with the adjacent log  11  and the post  10 . The engagement of the embossments  60  with the part cylindrical slot  17  ensures the key  32  moves with the logs  11  and slides within the key slide  70 . 
         [0042]    Thus, the spline assembly  30  provides a relatively low friction slide member in the post  10  that permits key  32  to slide in a controlled manner within the key slide  70 . The key  32  is secured to respective ones of the logs  11  by expansion of the key members  32   a ,  32   b  so as to move with the logs  11  relative to the post  10 . In this manner, the integrity of the log walls  2  is maintained by inhibiting gaps from opening between the logs  11 .