Log building construction
BACKGROUND OF THE INVENTION 
     This invention relates in general to log structures and deals more particularly with improvements in prefabricated log buildings. The present invention relates particularly to buildings formed from natural logs which may vary somewhat in diameter and which are partially finished and precut to interfit for rapid accurate assembly. Log buildings of the aforedescribed general type are characterized by relatively thick walls which provide a high degree of natural insulation without further interior or exterior finishing. However, in order to realize maximum benefit from the natural insulating qualities of the wood it is essential that the joints between adjacent log courses and at the corners of the building be substantially weathertight. One common type of roof construction utilized in such log buildings includes rafters which have bird-mouthed notches to engage upper log courses of the associated building walls so that the latter log courses are substantially shielded from the rays of the sun. Such a closely overhanging roof structure may also interfere, to some degree, with air circulation near the upper portion of the walls so that the upper log courses may become affected by mildew or mold. Further, joints at the juncture between the walls and the roof of the building and the arrangement of insulation at this juncture is often unsatisfactory, resulting in excessive heat loss in this critical region. The present invention is concerned with the aforesaid problems. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention a log building has a log joint formed by horizontally extending logs assembled in right angular relation to each other. Each log has horizontally disposed upper and lower planed surfaces. A tongue projects from the upper surface of each log and extends longitudinally thereof. Each log also has a groove which opens through its lower surface and extends in parallel relation to its tongue. A vertically disposed mortise opens laterally outwardly through one log in spaced relation to one of its ends and has a generally V-shaped outwardly diverging outer end portion and a generally rectangular inner end portion which forms a junction with the outer end portion. Another log has a tenon which is received in and substantially complements the inner end portion and an associated part of the outer end portion of the mortise, 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary perspective view of a corner of a building embodying the present invention. 
     FIG. 2 is a fragmentary plan view of the building corner shown in FIG. 1. 
     FIG. 3 is a fragmentary exploded perspective view of several component parts of the corner shown in FIG. 1. 
     FIG. 4 is a fragmentary sectional view taken along the line 4--4 of FIG. 2. 
     FIG. 5 is a fragmentary bottom view of a typical mortised log. 
     FIG. 6 is a fragmentary vertical sectional view through a portion of a building and shows an overhanging portion of the roof structure. 
     FIG. 7 is a fragmentary sectional view taken generally along the line 7--7 of FIG. 6. 
     FIG. 8 is a fragmentary sectional view taken along the line 8--8 of FIG. 7. 
     FIG. 9 is similar to FIG. 6, but shows another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Turning now to the drawings and referring particularly to FIGS. 1-5, a building embodying the present invention has a corner, indicated generally at 10, formed by intersecting walls, designated generally at 12A and 12B. The walls are respectively formed by courses of logs from which bark is or may be stripped or peeled and which have finished interengaging portions, as will be hereinafter further described. The logs may vary in diameter within a predetermined range and retain a rustic appearance except for the previously mentioned finished portions, however, for convenience the logs illustrated in the drawings are of uniform appearance. 
     Considering the building corner 10 in further detail, the wall 12A is formed by a plurality of horizontally extending log courses arranged in vertically stacked tongue and groove relation and includes logs 16a and 18a. Similarly, the wall 12B comprises a plurality of logs laid horizontally upon each other in tongue and groove relation and includes logs 16b and 18b. Each log course of the wall 12A is joined at a right angle corner to an associated log course of the wall 12B by a mortise and tenon joint. 
     Referring now particularly to FIG. 3, the log 16a, designated a mortise log, comprises a log cant which has horizontally disposed upper and lower finished surfaces respectively designated at 20a and 22a. A tongue 24a, which has a generally rectangular cross section, projects above the upper surface 20a  and extends longitudinally of the log 16a. A groove 26a opens through the lower surface 22a and extends longitudinally of the log in parallel relation to its tongue 24a. The groove has a generally rectangular cross section which substantially complements the vertical cross section of the tongue 24a. The longitudinal center lines of the tongue 24a and the groove 26a lie generally within a vertical reference plane P, shown in FIG. 2, which contains the longitudinal center line of the log 16a. 
     A vertically disposed notch or mortise, indicated generally at 28a, is formed in the log 16a and spaced inwardly from an associated one of its ends. The mortise 28a opens laterally outwardly through one side of the log and has a generally V-shaped outwardly diverging outer end portion defined by vertically disposed wall surfaces 30a, 30a which form an included angle of 90°, as best shown in FIG. 2. The wall surfaces 30a, 30a each form a 45° angle with the plane P, substantially as shown. The mortise 28a further includes a generally rectangular inner end portion indicated generally at 31a and defined by a vertically disposed inner end wall 32a, which lies within the reference plane P, and a pair of opposing vertically disposed side walls 34a, 34a which form junctions with the side walls 30a, 30a. The width of the rectangular inner end portion 31a, measured longitudinally of the log 16a, is substantially equal to the width of its tongue 24a. Its lateral depth is approximately one-half the thickness of the tongue. It should also be noted that the mortise inner end portion 31a is partially defined by the tongue 24a. 
     A saddle notch 36a formed in the log 16a, as best shown in FIG. 5, opens through its lower surface 22a, is laterally aligned with the mortise inner end portion 31a, and extends in a direction normal to the reference plane P. The notch 36a has a generally rectangular vertical cross section which complements the cross section of the tongue 24a. 
     The mortise log 16a may also have a shallow vertically disposed notch, such as indicated generally at 38a, for a purpose which will be hereinafter further discussed. The notch 38a is laterally aligned with the mortise 28a, but opens outwardly through the opposite side of the log. It is defined by a vertically disposed inner end wall 40a generally parallel to the plane P and a pair of vertically disposed and spaced apart side walls 42a, 42a which diverge inwardly toward the inner end wall 40a and toward each other. The side walls 42a, 42a form an included angle of 90° and angles of 45° with the plane P, substantially as shown. The mortise log 16b is substantially identical to the mortise log 16a, previously described, but bears the letter b suffix because of its position within the wall 12B. The log 18b, designated a tenon log is joined with the log 16a and has a tenon 44b formed on one end for interengagement with the mortise 28a. It is formed from a log cant similar to the cant used to make the log 16a, and has a tongue 24b which projects above its upper surface 20b and a groove 26b which opens through its lower surface 22b. The tenon 44b has a generally vertically disposed rectangular outer end portion 26b, which is partially defined by the tongue 24b. The width of the end portion 46b is substantially equal to the lateral width of the tongue 24b. The tenon 44a is further defined by vertically disposed surfaces 48b, 48b which form an included angle of 90°. The surfaces 48b, 48b further form angles of 45° with a vertical reference plane P&#39;, shown in FIG. 2, which contains the longitudinal axis of the log 18b. The tenon log 18a is substantially identical to the tenon log 18b, but bears the letter a suffix, because of its position within the wall 12A. 
     When the building corner 10 is assembled, log courses 16a and 16b and log courses 16b and 18a, respectively, are assembled in interfitting relation, substantially as shown in FIGS. 1 and 3. Specifically, the tenon 44b on the log 18b is received within the mortise 28a formed in the log 16a. In like manner, the tenon log 18a is assembled with the mortise log 16b. 
     In assembly, the tongue 24a on the log 18a extends for some distance into the tongue 24b on the log 16b. In like manner, a portion of the tongue on the log 18b extends into the tongue on the log 16a with which the log 18b is joined. The groove 26a in the log 16a receives the tongue 24a on the log 18a immediately therebelow. The straddle notch 36a in the log 16a straddles an associated portion of the tongue 24b on the log 16b immediately therebelow. Thus, the tongues 24a and 24b on the logs 18a and 16b cooperate with each other and with the logs 16a and 18b to provide a substantially continuous weathertight barrier which extends through the corner 10. Thus, when the log courses which comprise the walls 12A and 12B are assembled in vertically stacked tongue and groove relation, each mortise joint cooperates with an associated tongue and groove joint to provide a substantially continuous weathertight barrier which extends through the building corner 10. 
     If desired, slight clearance may be provided between each tongue and its associated groove and/or each mortise and its associated tenon to accommodate a suitable sealing or caulking compound. However, the various tongues and grooves and mortise and tenon joints may be arranged for close fit relationship and such caulking or sealing compound as may be desired may be applied to the interior and/or exterior surface of the log walls at the junctures between adjacent logs after the building walls have been assembled. 
     In the illustrated construction, each mortise log has an extending end portion, that is an end portion which extends beyond the log courses immediately above and below it, which courses are formed by tenon logs. If desired, log end pieces may be provided to fill the spaces between the extending end portions of the mortise logs thereby creating the appearance that the walls are formed by logs which may be of substantially equal length interfitted in crossing relation at the corners. Such a log end piece is shown in FIGS. 1-3 and indicated generally by the reference numeral 50b. The illustrated log end piece 50b is made from a log cant and has upper and lower surfaces respectively indicated at 20b and 26b. A tongue 24b projects above the upper surface and a corresponding groove 26b is formed which opens through the lower surface. An end portion of the log end 50b is received within and generally complements an associated portion of the notch 38a. The log end 50b is laid horizontally in tongue and groove relation upon the extending end portion of the log 16b and extends outwardly in normal relation to the log 16a in general longitudinal alignment with the log 18b. Thus, the log end piece 50b comprises a false log end which appears to be an extension or continuation of the log 18b. In like manner, another log end piece 50a is provided which appears to comprise an extending end portion of the log 18a, as shown in FIGS. 1 and 2, however, this log end piece is omitted from FIG. 3 for clarity of illustration. 
     Referring now to FIGS. 6 and 7, the eave portion of a typical roof structure embodying the invention is indicated generally by the reference numeral 52. The illustrated eave structure 52 facilitates provision of improved weathertight joints and the improved application of insulating material in this critical portion of the building where high heat loss may be anticipated. Referring particularly to FIG. 6, the building has a wall 12A which includes log courses 16a and 18a. Parallel joists 54, 54 supported on the upper log course 16a extend between the wall 12a and an opposite wall of the building (not shown) and may support conventional flooring material, as shown in FIG. 7. The outer end portion of each joist 54 extends outward in cantilever position beyond the wall 12A and has its lower surface rabbeted to a depth substantially equal to the vertical dimension of the tongue 24a on the log 16a to engage the tongue, substantially as shown. Each joist 54 has shallow vertically disposed notches 56, 56 which open laterally through its opposite sides in vertical alignment with the wall 12A. The configuration of each notch 56 is generally similar to the configuration of the notch 38a, previously described. 
     Filler logs 58, 58 laid horizontally upon the log course 16a extend between adjacent joists 54, 54 and have end portions which are received within and generally complement notches 56, 56, as best shown in FIG. 7. The lower surface of each filler log 58 is rabbeted as best shown in FIG. 8 to rest on the tongue 24a of the upper log course 16a. Rafters 60 secured to the outer end portions of the joists 54, 54 are supported, in part, by rafter braces 62, 62 which extend up from the joists 54, 54, as shown in FIG. 6. The rafters support a conventional sloped roof structure. 
     A soffit 64 which has a thickness substantially equal to the vertical dimension of the tongue 24a is fastened to the underside of the outwardly extending joists 54, 54, as best shown in FIG. 6. The soffit 64 has an inner marginal edge portion 66 disposed between the joists 54, 54 and the upper surface 20a of the log course 16a and rests upon the latter upper surface. The soffit further includes a vertically disposed inwardly facing inner edge 68 in substantial engagement with an associated outwardly facing side surface of the tongue 24a. If desired, suitable sealing or caulking material may be provided between the inner edge of the soffit and the associated side edge of the tongue 24a. 
     The eave structure 52, is finished by a facia board 70 fastened to the outer ends of the joists 54, 54. A vent screen, such as indicated at 72, associated with the soffit may be provided, if desired. Insulating material 74 is preferably applied, substantially as shown in FIG. 6, to minimize heat loss in this critical region of the building. 
     Another roof construction which provides substantial eave overhang is shown in FIG. 9. The illustrated structure includes a log wall 12A which has an upper log course 16a. A plurality of joists 54&#39; supported on the wall 12A and an opposite wall of the building (not shown) have overhanging or cantilevered portions which extend out beyond the wall 12A. Each joist 54&#39; has a saddle notch 53 in its lower surface to receive the tongue 24a on the log 16a. Each joist 54&#39; has vertically disposed notches 56&#39;, 56&#39; in its opposite sides substantially identical to the notches 56, 56, previously described, for receiving the associated end portions of filler logs 58&#39;, 58&#39; which are laid horizontally upon the log 16a and extending between adjacent joists 54&#39;, 54&#39;, substantially as shown in FIG. 9. Each filler log 58&#39; has a tongue 24 which projects above its upper surface and a groove 26 in its lower surface for receiving the tongue 24a on the log course 16a therebelow. The joists and the filler logs are dimensioned so that the upper surfaces of the filler logs, designated 20, are substantially aligned with the upper surfaces of the joists and the tongues 24, 24 on the filler logs extend above the upper surfaces of the joists 54&#39;, 54&#39;, as best shown in FIG. 9. A soffit 64&#39; is supported on the upper surfaces of the cantilevered portions of the joists 54&#39;, 54&#39;. The soffit has an inner marginal edge portion which rests on the upper surfaces 20 of the filler logs and an inwardly facing inner edge 68&#39; which engages an associated side edge of the tongues 24, 24. Rafters 60&#39;, 60&#39; (one shown) rest on the outer end portion of the soffit and are supported, in part, by rafter braces 62&#39;, 62&#39; which project from the rafters, substantially as shown. The rafters support a conventional roof structure which terminates near a facia board 70&#39; secured to the outwardly extending ends of the joists 54&#39;, 54&#39;. Flooring material may be laid on the joists inwardly of the walls, substantially as shown. Insulating material 74&#39; is preferably applied, as shown, to minimize heat loss. A vent 72&#39; may also be provided.