JOINT STRUCTURE

Abstract: Joint structure for joining walls built from logs (1) placed one over the other, said joint structure comprising a post (2) and joint elements in the post and in the log ends for joining them together. The joint elements consist of dovetail joints, by means of which the logs (1) are joined and locked to the post (2). Moreover, the post (2) comprises covering ledges (5) overlapping the sides of the logs.

Description: JOINT STRUCTURE The present invention relates to a joint structure as defined in the preamble of claim 1. Traditionally, the corners of log walls are constructed using crib joints, by making mutually cor¬ responding cut-outs or notches in the opposite log surfaces to be placed one over the other, so that in¬ tersecting logs can be stacked tightly on top of each other. A crib joint is massive in respect of both weight and appearance. There are several problems or drawbacks asso¬ ciated with a crib corner. The log portions extending beyond the corner constitute a significant increase in log material consumption. Thermal insulation of the corner is difficult because gaps tend to be formed between the criss-cross logs as they gradually twist, contract, swell and move in different ways. Another problem is that building a good and tight crib struc¬ ture is a difficult and slow job and that a crib joint can join only two walls together. A further drawback in a crib structure can be found in the fact that the entire log building must be erected by mounting one tier of logs at a time, which means that erecting the log framework is a slow and difficult business. In an attempt to eliminate these problems, Norwegian patent 37752 presents a log structure in which the corner consists of a post to which the logs are joined by their ends with dovetail joints. However, this solution is not a workable one. If the joints are made tight and neat in appearance, the structure is almost impossible to erect. Again, if the joints are made loose enough to permit erection, they are not tight and sufficiently rigid and they al- so look untidy. The object of the present invention is to eliminate the drawbacks described above. A specific object of the invention is to present a new type of joint structure for the making of log walls so that the joints between the logs will be sturdy, flexible, warm, tight and easy and simple to build and also easy to take apart when necessary. A further object of the invention is to present a log joint structure that do¬ es not require any nails, screws, bars or any other separate joining devices made of metal or other mate¬ rials. As for the features characteristic of the in¬ vention, reference is made to the claims. The joint structure of the invention compri¬ ses a vertical post and joint elements in the post and in the logs to be placed in it by their ends, said joint elements serving to join the logs to the post. The joint elements consist of dovetail joints, by me¬ ans of which the logs are joined to the post and also locked in position. According to the invention, the post comprises as an essential part of it, either on both sides of the dovetail joint or on one side of it, a covering ledge, i.e. an integral and essential part of the post which extends over the entire length of the post and overlaps the ends of the logs joined to the post, extending over the side face of the logs through some distance from the log end. This makes it possible to achieve at once a finished and tight joint between the log and the post, a joint that looks ele¬ gant without any mouldings whatsoever. The dovetail joints used in the structure are preferably implemented by providing the log end with a tongue and the post with a groove. The structure can also be implemented in a converse manner, i.e. by pro¬ viding the log end with a groove and the post with a tongue. It is also possible within the framework of the inventive idea to have a groove both in the log end and in the post, in which case, when the log and post are aligned with each other, a double-tongued batten shaped to fit the space formed by the grooves can be inserted into the grooves, so that the wedge- shaped batten interlocks the logs and the post. The post preferably comprises at least two dovetail joint elements directed or opening in diffe¬ rent directions, which elements may be at right angles, at a straight angle or in any arbitrary angle to each other. It is also possible to join several log walls extending in different directions to the same post. In an embodiment of the invention, the post is provided with a groove and comprises a detachable edging strip incorporating a covering ledge and exten¬ ding over the entire length of the post. This allows the groove to be completely opened on one side so that the logs can be lifted from the side into position over each other in the groove in the post, the edging strip being finally fixed back to the post to lock the logs in position. The edging strip can be secured using suitable screws, and even glue can be used if necessary. In an embodiment of the invention, a post connecting two walls of a corner to each other at an angle of 90° consists of two identical profiles glued together by their mutual contact surfaces and forming an angle of 45° to the walls to be erected. Thus, the¬ se same dovetail joint profiles can be used to make a straight angle, i.e. to extend a wall in the same di¬ rection, by gluing the profiles together by their con- tact surfaces the other way round. In addition, in this embodiment preferably a narrow wedge-shaped ele¬ ment can be glued between the contact surfaces. In this way, by using a suitable wedge-shaped element, corners with walls at different angles can be built from the same basic profile, the angles being prefera¬ bly 120° and 135°. In an embodiment of the invention, the dove- tail joint comprises a tightening element used to tighten the log longitudinally to the post. The tigh¬ tening element may consist of wedges of a length sub¬ stantially corresponding to the log height, which are forced into the space between the tongue and the groo¬ ve when the wall is being erected, thus causing the oblique contact surfaces of the tongues and grooves to be pressed tightly against each other. It is also pos¬ sible to make a slot in the bottom of the tongue or groove to allow the use of a thicker and more robust wedge-shaped tightening element. The tightening element may also consist of a shouldered tightening strip, in which case the post is provided with wedge-shaped shoulders corresponding to the shoulders on the strip. In this case, when the log wall is being erected, the shoulders on the strip and those on the post lie as closely together as possible, and finally an impact is applied to one end of the shouldered strip so that the strip is forced to move outward from the post by its shoulders, thereby pus¬ hing the logs tightly against the dovetail joints of the post. The shoulder distance on the shouldered strip is preferably equal to the log height, so that each log will be pressed by a shoulder. Another possibility is that no shoulders are formed in the post but instead two shouldered strips in opposite orientation are used, with the shoulders placed oppositely. In this case, after the logs have been mounted in place, when one of the strips is held stationary and an im¬ pact is applied to the other one, the logs are tigh¬ tened in position. In this embodiment, the logs can be loosened just as easily by applying an impact to the strip that was held stationary when tightening the logs. The tightening element used in the joint structure of the invention may also consist of various eccentric elements which are placed between the ton¬ gues and the grooves and which can be turned from the outside of the post. The joint structure of the invention has sig- nificant advantages as compared with prior art. The joint structure is a self-stiffening and self-locking structure, in other words, it requires no separate fi¬ xing elements. The joint structure can be easily tigh¬ tened to make it completely tight if necessary. The joint surfaces in the joint structure are relatively long and always -longer than the reserve between logs, so the leakage caused by the joint will be insignifi¬ cant. Moreover, thanks to the covering ledges, the parts of the dovetail joint can be fabricated to suf- fici ntly loose dimensions to allow easy erection as the flanks of the logs are tightened between the cove¬ ring ledges. The structure permits free natural motion and setting of the logs relative to the vertical post. In addition, the structure allows very simple and fast erection and disassembly without its components being damaged in any way during these operations because no fixing devices are needed, so using the joint struc¬ ture of the invention it is possible to build various partitions of neat and representative appearance, tem- porary interior structures and all sorts of temporary structures which later need to restructured or disas¬ sembled altogether. In the following, the invention is described in detail by referring to the attached drawings, in which Fig. 1 presents a perspective view of a joint structure according to the invention, Fig. 2 presents a sectioned view of a struc¬ ture substantially consistent with the structure in Fig. 1, Fig. 3 presents an embodiment of the inventi¬ on, Fig. 4 presents another embodiment of the in- vention, Fig. 5 presents a third embodiment of the in- vention, Fig. 6 illustrates a tightening arrangement, Fig. 7 illustrates a post structure, Fig. 8 illustrates another tightening struc¬ ture, and Fig. 9 illustrates a post structure according to the invention. The joint structure presented in Fig. 1 and 2 comprises a post 2 connecting two log walls 1 at right angles to each other. The log ends are provided with vertical dovetail joint tongues 3 and the post is pro- vided with corresponding grooves 4. Therefore, the tongues of the logs 1 can be slid in from the upper end of the post into the grooves so that the logs 1 are secured to the post 2. Due to the wedge-shaped structure of the dovetail joint, the logs need not be fastened in any other way but are securely attached to the post solely by the joint. An essential part of the post structure are the covering ledges 5, which extend through some distance from the log end onto the sides of the logs. Thus, the covering ledges cover the joint and any machining traces that may have been left at the log ends, so a completely finished joint is obtained immediately after the logs have been mounted. In Fig. 2, the post 2 is composed of several parts glued together, so a more rigid and straight post is obtained. In addition, the surface parts that remain visible on the post can be made of higher qu¬ ality wood with fewer knots while the inner parts are made of more knotty raw material. Fig. 2 further shows a door frame 16 joined to the post 2. Attached to the frame is a separate batten 17 with a dovetail tongue of a shape correspon¬ ding to the groove 4 in the post 2. It is naturally also possible to fabricate a frame that in itself com¬ prises a tongue. The post profile in Fig. 2 additionally com¬ prises a hole 20 going through the post. The hole has two functions. It can act as a guide when the two op¬ posite profile parts are being joined and glued toget¬ her. A suitable bar or pipe can be inserted into the hole, so the parts will be accurately aligned when joined and pressed together. In a finished post, the hole can contain a threaded bar allowing a bottom beam under the post and a top beam on top of it to be tigh¬ tened to form a rigid framework. This will not neces¬ sarily produce any pressure on the logs joined to the posts, but the logs can still undergo natural motion and setting depending on the conditions. Fig. 3 presents an embodiment of the inventi¬ on in which two adjacent log walls extending in the same direction are joined to a post 2 with dovetail joint elements 6. In this case, one of the walls forms an exterior wall 7 and the other an interior wall 8, with an insulation space left between them. This space can be filled with suitable insulating material 9, such as e.g. cellulose wool introduced by blasting, the wall as a whole will have a structure that allows breathing and thus corresponds to a solid log wall. Fig. 4 presents and embodiment of the inven¬ tion in which both the post 2 and the log 1 end are provided with a groove 4. In this case, the logs are joined to the post by means of a separate double- tongued batten 11 shaped to fit the shape of the two opposite grooves. In this embodiment, the double- tongued batten 11 is mounted in place in pieces of a length corresponding to the height of e.g. one log or three logs, and these pieces are forced into position after an appropriate number of logs have been mounted, because mounting a full-length batten 11 may be diffi¬ cult. In the embodiment presented in Fig. 5, the post 2 comprises a detachable edging strip 10 attached to the post with a screw 18. The edging strip forms part of the groove 4 of the post and also comprises a covering ledge that covers the side of the log end. In this case, the logs 1 can be stacked on top of each other and placed against the post 2 without having to slide them into the groove from the end of the post 2. When the logs are in place, the edging strip 10 is mounted and screwed fast, thus locking the logs in po¬ sition in the post. Normally, when a dovetail joint according to the invention is used, a sufficiently tight and rigid joint that stiffens the whole structure is obtained by just sliding the logs into the grooves of the posts and stacking the logs one over the other to form a complete wall. However, if necessary, the joint can be tightened e.g. by forcing a wedge 12 into the space between the post 2 and the end of each log 1 as illus- trated by Fig. 6. The wedge presses the log 1 and the post 2 in opposite directions, thus causing the obli¬ que surface 14 of the tongue to be pressed tightly against the corresponding oblique surface 15 of the groove (Fig. 7) . The tongues and grooves can be fabricated to loose-fit dimensions such that a wedge 12 of suitable size can be inserted between them. It is also possi¬ ble, as illustrated by Fig. 7, to make a separate key slot 21 in the bottom of the groove for the tightening wedge. It is further possible to use in this slot a tightening element 13 as shown in Fig. 8, i.e. a shouldered tightening strip, in which case the bottom of the key slot is provided with corresponding shoul¬ ders in reverse orientation. It is further possible to use two tightening strips 13 placed in the key slot in converse orientations with the shoulders opposite to each other, the strips being tightened and wedged up after the logs have been mounted. The key slot 21 can also be used as a sealing channel, in other words, a suitable sealing strip pressed against the log end is placed in the key slot. Further, it is possible to use a separate sealing channel or channels in addition to the key slot. Fig. 9 shows a profile view of an embodiment of the invention in which the post is composed of two identical dovetail profiles 18. An individual profile 18 may be made up of one or more parts. The joint sur¬ faces of the profiles are at an angle of 45° to the walls to be joined to them, so the profiles will form a 90° corner if they are joined directly together. In the case illustrated by the figure, however, a key profile 19 designed to produce a desired angle between the walls joined to the post is glued between the do¬ vetail profiles. In this way, by only using different key profiles, different angles between walls, e.g. 45, 60, 120, 135 150 and 180°, are achieved with the same dovetail profiles 18. The invention has been described above by gi¬ ving examples and referring to the attached drawings, but different embodiments are possible within the fra¬ mework of the inventive idea defined by the claims.

Claims: CLAIMS 1. Joint structure for joining walls built from logs (1) placed one over the other, said joint structure comprising a post (2) and dovetail joints both in the post and in the ends of the logs to join them together, c h a r a c t e r i z e d in that the post (2) comprises as an integral and essential part of it, at least on one side of the dovetail joint structure, a covering ledge (5) overlapping the sides of the logs (1) over some distance from the log end. 2. Joint structure as defined in claim 1, c h a r a c t e r i z e d in that the tongue of the dove¬ tail joint belongs to the end of the log (1) while the groove (4) belongs to the post (2). 3. Joint structure as defined in claim 2, c h a r a c t e r i z e d in that the post (2) comprises covering ledges (5) overlapping both sides of the log (1) ■ 4, Joint structure as defined in any one of claims 1 - 3, ch a r a c t e r i z e d in that the post (2) comprises at least two dovetail joint elements for joining two walls oriented in different directions. 5. Joint structure as defined in any one of claims 1 - 4, c h a r a c t e r i z e d in that the post (2) comprises two adjacent and parallel dovetail joint elements (6) in order that the wall to be joined to the post can be built from an outer wall (7) and an inner wall (8) and a possible insulation (9) in the space between them. 6. Joint structure as defined in any one of claims 1 - 5, c h a r a c t e r i z e d in that the post (2) comprises a detachable groove edging strip (10) allowing the groove to be opened and closed again af¬ ter the logs (1) have been mounted. 7. Joint structure as defined in claim 1, c h a r a c t e r i z e d in that the post consists of two identical dovetail profiles joined together and a possible key profile (19) placed between them to chan¬ ge the directions of the dovetail joints. 8. Joint structure as defined in claim 1, c h a r a c t e r i z e d in that both the post (2) and the end of the log (1) are provided with a groove (4) and the post and the log are joined together by means of a double-tongued batten (11). 9. Joint structure as defined in any one of claims 1 - 8, c h a r a c t e r i z e d in that the dove- tail joint comprises a tightening element (12, 13) de¬ signed to press the oblique surfaces (14) of the ton¬ gue against the oblique surfaces (15) of the groove. 10. Corner structure as defined in claim 9, c h a r a c t e r i z e d in that the tightening element is a wedge forced into the space between the tongue and the groove.

Inventors: LEMINEN REIJO, SILLANPAEAE HEIKKI, LEMINEN, REIJO, SILLANPAEAE, HEIKKI
Applicants: HIRSISUUNNITTELU LEMINEN KY, LEMINEN REIJO, SILLANPAEAE HEIKKI, LEMINEN, REIJO, SILLANPAEAE, HEIKKI
Application year: 1997
Main classification: E04B2
IPC codes: E04B1, E04B2