The present invention relates to a round log wall defined in the introductory section of patent claim 1.

Round logs are generally used in building log cabins. The wall surfaces of these buildings are formed of horizontal protruding, round log side surfaces stac¬ ked on top of each other. A drawback with these wall surfaces is that the installation of various structures in connection thereto is troublesome; the wall surface is not even. For instance the securing of radiators, fitting of cupboards and shelves, installation of light partition walls as well as doors and windows or extra insulation layers is laborious and requires special procedures in order to achieve satisfactory results.

The object of the invention is to eliminate the above described drawbacks. A particular object of the invention is to make the interior surfaces of ex- ternal walls in round log cabins to be such that the installation of additional structures thereto becomes as easy as in ordinary buildings which are not const¬ ructed of round logs. Moreover, a particular object of the invention is to facilitate and improve the instal- lation of doors and windows to a round log building.

The round log wall of the invention is cha¬ racterized by the novel features enlisted in the patent claim 1.

The round log wall of the invention is reali- zed of logs which are round in cross-section, i.e. round logs. According to the invention, the surfaces or the round logs are machined, at least on the side of one wall surface, to a suitable depth and length, to be essentially planar surfaces, so that these planar sur- faces constitute a uniform wall area. This wall area is formed in between corner joints. At least in the corner areas, the logs are left in their natural round shape.

That part of the wall which has a planar surface can at largest be as large as a wall surface in between two corner joints, but it can also be a relatively small area, where the desired internal structures, such as radiators, can be fitted and installed.

In a preferred embodiment of the round log wall, the round log surfaces are machined in the vi¬ cinity of structures, such as doors, windows and/or in the vicinity of the junctions of light partition walls made of some other material, on the sides of both wall surfaces, to a suitable depth and length, to form pla¬ nar surfaces.

Owing to this wall structure, particularly the installation of doors and windows becomes easier. Standard-size doors and windows, designed for standard wall thickness, can be used for several different di¬ mensions of round logs. Another advantage of this wall structure is that the doors and windows can be instal¬ led in a more compact fashion in the apertures reserved for them.

In another preferred embodiment of the round log wall, the planar surfaces of the round logs are machined to a depth in the region of 10 - 15 % of the thickness of the round log. An advantage of this embo- diment is that the round logs are machined to a relati¬ vely small extent, but the desired beneficial effects are still achieved. In this case the wall surface is not a uniform plane surface, but small recesses remain in between the logs owing to their round shape. Howe- ver, the wall surface is essentially planar in configu¬ ration.

In another preferred embodiment of the round log .wall, such planar surfaces of the round logs that are located adjacent to door or window apertures and in external walls are provided, at least on the side of one planar surface, with a groove for fitting the insu¬ lation in. By using this embodiment, doors and windows

can be insulated easily and reliably.

In another preferred embodiment of the round log wall, the round and planar surfaces of the round log are connected by a curved surface. Naturally the shift from round to planar surface in the said log may be realized directly by using a straight surface in between, but it is esthetically more pleasant to cut the transition surface in a curved fashion. Moreover, a particularly pleasant look is thus achieved in the areas around doors and windows.

In yet another preferred embodiment of the round log wall, the radius of curvature of the curved surface corresponds, at least roughly, to the diameter of the round log. The curved transition surface between the round and planar surface in the said log is parti¬ cularly good-looking when a relatively gentle curvature is applied.

The invention is explained in more detail below, with reference to the appended drawings, where figure 1 illustrates a round log wall of the invention; figure 2 illustrates a longitudinal cross— section A - A of the round log wall of figure 1; figure 3 illustrates a vertical cross-section B - B of the round log wall of figure 1; figure 4 illustrates a part of another round log wall of the invention, seen from outside the buil¬ ding, with a window installed in the said round log wall; figure 5 illustrates the round log wall of figure 4, seen from the inside of the building; figure 6 shows, in enlarged illustration, a longitudinal cross-section C - C of a detail in the round log wall of figures 4 and 5, at the junction of the- round log and window; figure 7 illustrates a vertical cross-section D - D of the round log wall of figure 4; and

figure 8 is a partial longitudinal cross-sec¬ tion of a round log wall of the invention, which log wall is connected to a partition wall.

Figure 1 illustrates a round log wall 1, which is compiled of logs with a round cross-section, i.e. of round logs 2. These are stacked on top of each other, matched and secured in a known fashion. The corners, i.e. junctions 3 with similar log walls are also realized in a known fashion. On the inside la, the surfaces of the round logs 2 are machined to be even and straight surfaces, i.e. planar surfaces 4, so that the planar surfaces of the logs together form a uniform area. In the round log wall of figure 1, this area extends over the whole wall, so that the corner sections are left as unbroken round log surfaces, and in the area adjacent to the corner junctions, the walls are left in their natural round shape. As is seen in figure 1, in the areas 5 near the junctions 3, the round logs are left untouc- hed. The round, entire surface 5 and planar surface 4 of the round log are interconnected by using a curved surface 6.

The surfaces of the round logs 2 are machined to become planar surfaces 4, so that the planar surfa- ces of the superimposed logs form a uniform surface area. In each log 2, the planar surface 4 is machined to a suitable depth and length. In the embodiment of figure 1, the uniform planar surface extends over the whole wall surface, which facilitates the installation of the window 7, radiator 8 and wall socket 9. Respec¬ tively, the installation of for instance skirting boards 10 and more generally the matching of the floor against the wall surface becomes easier, as is seen in figure 3. At the window 7, both the exterior and inte¬ rior surfaces la, lb of the round log wall 2 are machined to constitute planar surfaces 4a, 4b, as is

seen in figure 2. On the exterior surface lb of the wall 1, the round logs 2 are machined to form planar surfaces 4b only around the installation aperture of the window 7. Figures 4 and 5 illustrate a part of a round log wall of the invention, with a window 11 installed therein. The surfaces of the round logs 2 are machined, around the installation apertures of the window 11, on the sides of both the interior and exterior wall surfa- ces la, lb, to form planar surfaces 12a, 12b. Together these planar surfaces form a rectangular area where an aperture for the window is suitably arranged. In this aperture, there is then installed the window 11 proper, and around the window there are secured the interior and exterior covering boards 13, 14. As is seen in figure 4, the protecting, slanting covering board 13a fitted above the window also is arranged in the planar surface area 12b of the round log 2, so that the said board is easily secured in place. The planar surfaces 12a, 12b of the round logs 2 are connected to the round log surfaces 15a, 15b by means of curved surfaces 16a, 16b, in similar fashion as in the round log wall of figure 1.

Figure 6 shows a longitudinal cross-section C - C of the wall structure of figures 4 and 5. This drawing illustrates how the round log wall 1 and the window 11 are connected to each other. The same refe¬ rence numbers for the surfaces of the log 2 are used as in the above description of other drawings. At the end of the round log 2, there is provided a vertical groove 17, and in connection thereto a matching vertical pin bar 18. The window frame 19 is fitted in the window aperture, in between the vertical pin bars 18. The gaps in the round log head 2a, the vertical pin bar 18 and the window frame 19 are insulated with heat insulation 21. By means of an additional frame 20, the total width of the window frame 19 is made to match the width of

the round log head 2a. The exterior covering board 13 and the interior covering board 14 are installed on top of the vertical gaps left in the round log wall 1, the vertical pin bar 18 and the window frame 19. At the heads 2a of the round logs 2, in the planar area 12b, there are arranged grooves 22 at right angles to the longitudinal axis of the log. These groo¬ ves 22 are arranged in the superimposed logs 2 in such a fashion that together they form a long, uniform groo- ve, which is located at a slight distance from the edge of the window installation aperture. In this groove 22, there is inserted the insulation 23, as is seen in figures 6 and 7. Advantageously the insulation is a uniform insulation tape, extending over several logs 2, over the height of the whole installation aperture. When the exterior covering board 13 is fitted in place, it rests partly against the planar surfaces 12b of the round logs 2 and is simultaneously pressed against the insulation tape 23, thus insulating the gap left in between the covering board 13 and the heads 2a of the round logs. In between the exterior covering board 13 and the additional frame 20, there can also be inserted an insulation 26, as is illustrated in figure 6.

In between the window 11 and the round log wall 2, there can also be arranged another groove 24 on the interior side, and a matching insulation 25 inser¬ ted thereto, as is illustrated with dotted lines in figure 6. In principle the groove 24 and insulation 25 are similar as the groove 22 and insulation 23 arranged on the exterior of the round log wall 2. In this case, the insulation 25 insulates the gap left in between the interior covering board 14 and the log heads 2a.

The said grooves 22, 24 and insulations 23, 25, or at least the grooves 22 and insulation 23 meant for the exterior wall, can also be arranged in the planar surface areas of the covering boards and the logs located thereunder. Thus the window is insulated

on all sides.

The insulation provided in between the exte¬ rior covering board 13 and log wall 2 as well as the frame 20 ensure that dampness has no access to the apertures left in between the log wall 2 and the window 11. Insulation also prevents the formation of possible cold conductors in the junction.

The above described junction and insulation procedure of round log wall and window can naturally be applied in connection with doors, too.

Figure 6 illustrates how such planar surfaces 12a, 12b of round log walls 2 that are generally con¬ nected with apertures made in the wall for doors/win¬ dows should be dimensioned. The planar surfaces 12a, 12b of the round logs are machined to a depth a, which is in the region 10 - 15 % of the thickness 1 of the round log. For example, when the thickness of the round log is 190 - 210 mm, the machined depth a of the planar surfaces 12a, 12b is 20 mm, and if the thickness of the round log is 230 - 250 mm, the machined depth of the planar surfaces is 30 mm.

In this case the curved surfaces 16a, 16b connecting the planar surfaces 12a, 12b and the round log surfaces 15a, 15b are machined so that the radius of curvature R of these surfaces is roughly equal to the round log diameter, i.e. 1. Thus the planar surfa¬ ces and round surfaces are interconnected in a clear and pleasant way.

In the vicinity of the vertical surfaces of door and window apertures, the summed-up length s of the planar surface 12a, 12b and curved surface 16a, 16b from the round log head 2a is in the region of 200 mm, i.e. of the same order as the diameter 1 of the round log. With this procedure, the installation of covering boards and possible insulation is carried out easily, and moreover, in between the covering boards 13, 14 and the curved surfaces 16a, 16b, there is still left some

space, as is seen in figures 4, 5 and 6.

Figure 8 is a longitudinal cross-section illustrating how the round log wall 2 of the invention is coupled to a partition wall 27. Such a partition wall 27 is normally thinner than a round log wall 2. The junction in between the walls 2, 27 is realized in a simple fashion, by machining the round log surfaces on both sides to form planar surfaces 4, as was ex¬ plained earlier in connection with other embodiments. The junction 28 is covered by means of boards 29, 30 without creating any substantial gaps in between the two wall surfaces.

The invention is not restricted to the above described embodiments only, but several modifications are possible within the scope of the inventional idea defined in the appended patent claims.