The object of the invention is a method for producing a log construction, according to which method a log wall and an additional wall at a distance from the log wall are formed to make the log construction.

Using a log house as a modern house in year-round residential use has been restricted by the fact that the thermal insulation capacity of log walls is not sufficient as such. Thermal insulation must, therefore, be added to the log walls. The insulation is usually added on the log wall, on its interior surface, and covered by boards or panelling nailed to posts.

In a log wall construction, however, this type of insulation becomes a problem because the log wall subsides considerably with time. The board or panel construction used to cover the insulation, on the hand, does not subside at all. Especially with window openings and doorways it is extremely difficult to take into account changes to take place later during the construction stage. At these openings there should, therefore, be clear play to allow for the settling of the logs.

It is also known to build a log wall as a double construction. In this way, the interior wall and the outer wall can be interlocked, which means that no play needs to be built in for windows and doors. This type of construction has, however, proved problematic when the wall construction dries with time. This is because it has been found that gaps are formed in the interior logs as the interior wall dries more than the outer wall. Thus, humidity from inside can pass between the walls, but not all the way out as the outer wall is more tightly sealed. If the wall construction does not breathe naturally, the

humidity remaining inside the wall construction will be extremely detrimental to the durability of the construction.

The aim of the present invention is to eliminate the above problems and to achieve a method for producing a log wall construction in a new manner. It is characteristic of the method relating to the invention that the additional wall is formed of light-weight logs outside the log wall, at a distance from it, so that a light-weight log is interlocked with a log of the log wall located at essentially the same point. According to the invention, the light-weight logs are wooden elements which are substantially thinner than the actual logs of the construction.

According to a preferred embodiment of the invention, the light-weight logs of the additional wall are placed outside the log wall, at a distance from the log wall, in the vertical grooves formed at the ends of the logs of adjacent walls, so that the light-weight log is positioned at the same point as the log and parallel to it. The light-weight logs are essentially of the same height as the logs, and their appearance corresponds to that of a log.

According to another preferred embodiment, a horizontal light-weight outer wall log is interlocked by means of a connecting piece with a log located at the same point to form an integrated unit, or small element.

At the corner of the additional wall a vertical light¬ weight corner log is mounted in the vertical grooves formed at the ends of the logs of the log wall, so that the light¬ weight corner log forms an angle of essentially 45° with the wall surfaces. The light-weight corner log is not interlocked with the logs but can slide freely in relation to the logs as the logs settle.

The object of the invention also comprises a log wall

construction including a log wall and an additional wall located at a distance from it. It is characteristic of the log construction relating to the invention that the additional wall incorporates light-weight logs located outside the log wall, at a distance from it, and that the light-weight log of the additional wall is joined to the log of the log wall located at essentially the same point. The grooves of the light-weight logs have vertical play.

By means of the invention, the settling of the additional wall located outside the log wall construction can be made to correspond to the settling of the interior log wall, because the additional wall located outside will take in the humidity from outside. Since the interior log wall is, however, more tightly sealed and thicker than the outer additional wall made of light-weight logs, the wall construction breathes naturally and no separate damp proofing is necessarily reguired.

According to the invention, doorways and window openings can be made to fit more tightly, as the logs of the interior log wall and the light-weight logs fastened to them expand and contract together.

An advantageous aspect of the construction relating to the invention is that the interior log wall is not exposed to the weather, which means that the wall will remain unchanged. The outer light-weight log panelling takes the strain caused by the weather, and it can, if necessary, easily be renewed without the repair work disturbing living. The outer covering is quicker and easier to mount than the interior and the appearance can be made to correspond to that of a log wall.

According to a preferred embodiment, in the log construction relating to the invention, a horizontal light¬ weight outer wall log is joined, by means of at least one connecting piece, to a log located at the same point to

form an integrated unit, or small element.

According to yet another embodiment, the small element formed by the light-weight outer wall log and the log is joined to the small element of the adjacent wall, the element being essentially at the same height, so that the small elements of all walls at essentially the same height form a frame-like layer element.

The invention is described in the following by means of an example, with reference to the appended drawings in which

Figure 1 shows a horizontal section of the log wall construction relating to the invention as seen from above.

Figure 2 shows a vertical section of the log wall construction along line II-II of figure 1. Figure 3 shows a detail of the log wall construction of figure 2.

Figure 4 shows a detail of figure 2. Figure 5 shows a detail of the end of a log belonging to the log wall construction of figure 1. Figure 6 shows axonometrically the joint between the logs of figure 5.

Figure 7 corresponds to figure 6 and shows axonometrically a log joint to which the light-weight log panelling relating to the invention has been added.

Figure 8 shows a detail of the log wall construction of figure 1. Figure 9 shows the layer element of the log wall construction relating to the invention.

Figure 1 shows a horizontal section of the log wall construction relating to the invention, as seen from above. The figure shows that outside the log wall 10 located on the interior side of the construction is mounted light¬ weight log panelling 11 so that the ends of the light-

weight outer wall logs 12 are interlocked in the grooves 14 of the logs 13. Each horizontal light-weight outer wall log 12 is interlocked by means of a wooden connecting piece 15 with a parallel log 13 located at the same point. Each connecting piece 15 is fastened both to a log 13 and a light-weight log 12 located at the same point by means of screws 16 screwed obliquely from above.

At the ends of the logs 13 grooves 14 are formed, at the same point on both sides. Thus, in the first grooves the light-weight outer wall logs 12 can be mounted and in the second grooves, on the opposite side of the logs 13, the vertical light-weight corner logs 17, at the corners of the log wall construction. The grooves 14 may be identical on both sides of the log 13, because the edges of the light- weight corner logs 17 have been designed to fit in the grooves 14. In the construction of figure 1, the space between the log wall 10 and the outer panelling 11 formed of light-weight logs 12 is filled with insulating material 18, such as blowing wool.

Figure 2 shows a vertical section of the log wall construction of figure 1. Outside the interior log wall 10 is located, at a distance, outer log panelling 11 formed of light-weight logs 12. The light-weight outer wall logs 12 are located in the grooves 14 formed in the logs 13. Each light-weight log 12 is fastened to a log 13 located at the corresponding point by means of a wooden connecting piece 15 and screws 16 screwed obliquely from above. In figure 2, the log 13, the connecting piece 15 and the light-weight log 12 together form a small element 23 of the wall construction which acts as an integrated unit in the wall construction. In other words, the light-weight outer wall log 12 settles in the wall construction at the same time as the actual wall log 13 settles.

Figure 3 shows a detail of the log wall construction of figure 2. The figure shows that the light-weight outer wall

log 12, the log 13 located at the same point and the connecting piece 15 between them form - together with the screws 16 - a solid unit, or small element 23 which moves as a whole when the log construction settles. Thus, in the construction relating to the invention, the interior wall and outer wall do not expand and contract in different ways as in known constructions.

Figure 4 shows a detail of figure 2, where a part of the log wall 10 and a part of the outer panelling 11 formed by the light-weight logs 12 can be seen. The logs 13 and 13b have been placed on top of each other so that they form the interior wall of the building. To each log 13 is joined a light-weight outer wall log 12 by means of a connecting piece 15. In this example case, the connecting piece 15 has been fastened to the log 13 and to the light-weight outer wall log 12 by means of screws 16. In this way the log 13, the connecting piece 15 and the light-weight log 12 located at the same point as the log 13 can be made to form the unit shown in figure 3, that is, the small element 23.

Figure 4 also shows that the log 13b rests in the usual manner on the log 13 below it, but the light-weight outer wall log 12b joined by means of the connecting piece 15b to the upper log 13b does not rest with its entire weight on the light-weight log 12 below it. This is because a tongue- and-groove joint 21 has been formed between the light¬ weight outer wall logs 12 and 12b, the said joint allowing for vertical adjusting movement between these light-weight logs.

The possibility for this type of movement is important because the log construction will in any case settle with time. Therefore, the outer wall panelling formed of light¬ weight logs should not be made to bear the load intended for a log wall. Another advantage of this type of solution is that the wall construction breathes naturally. Thus, for example, humidity from inside the building can easily pass

out through the outer wall panelling formed of light-weight logs.

Figure 5 shows a detail of the end of a log 13 of the log wall construction relating to the invention. At the end of the log 13 is a log joint notch 19, in the known manner, but in addition, on both sides of the end of the log 13 there are, in accordance with the invention, similar notches 14 for the light-weight outer wall log and the light-weight corner log.

Figure 6 shows axonometrically the joint between the logs 13 of figure 5. The log joint is fully known as such, but the figure clearly shows the grooves 14 on both sides of the ends of both logs 13, the said grooves forming vertical guides in the construction for both the light-weight logs of the outer wall and the light-weight logs of the corner.

In figure 7, to the log joint of figure 6 have been added, in accordance with the invention, light-weight outer wall logs 12 in the grooves 14 at the ends of the logs 13, and at the corner a light-weight corner log 17. Each log 13 and the light-weight outer wall log 12 joined to it by means of the connecting piece 15 form an integrated unit, or small element 23 which moves as one piece when the log construction settles. The light-weight corner log 17 is not interlocked with the logs 13, but is able to slide freely in relation to the logs as the logs settle.

Figure 8 shows in greater detail the structure of the corner part of the log wall construction of figure 1. The grooves 14 formed on both sides of the ends of the logs 13 have been dimensioned so that the light-weight outer wall log 12 fits well into the groove. The light-weight corner log 17 is also placed in a similar groove 14 at the end of the log 13. Since the light-weight corner log 17 is as thick as the light-weight outer wall log 12, but is situated at an angle of 45°, the edges of the light-weight

corner log 17 must also be bevelled to an angle of 45°. In addition, on the inner surface of the light-weight corner log 17 are formed small additional grooves 20, by means of which the bevelled edge parts of the light-weight corner log 17 can be made to press completely inside the grooves 14.

In the structural example of figure 8, the light-weight outer wall log 12 is also fastened to the log 13 by means of a screw 22. Thus the adjacent small elements 23 interlocked with each other form a frame-like layer element 24, as shown in figure 9.

Figure 9 shows the layer element 24 of the log wall construction relating to the invention, the said element having been formed by joining together the adjacent small elements 23. The frame-like layer element 24 thus comprises the logs 13 of one layer on the inside of the wall construction, and at the same point on the outside, the light-weight logs 12, and the connecting pieces 15 between the logs 13 and light-weight logs 12. In the wall construction of a log building, the layer element 24 forms an integrated frame having the height of one log layer, the said frame settling as one piece when the log construction settles.

It is obvious to a person skilled in the art that the different embodiments of the invention may vary within the scope of the claims presented below.