EP1739245B1

EP1739245B1 - Log wall structure

Info

Publication number: EP1739245B1
Application number: EP06012477.3A
Authority: EP
Inventors: Jukka Rintamäki
Original assignee: Honkarakenne Oyj
Current assignee: Honkarakenne Oyj
Priority date: 2005-06-20
Filing date: 2006-06-19
Publication date: 2018-08-08
Anticipated expiration: 2026-06-19
Also published as: EP1739245A1; FI20050664A0

Description

TECHNICAL FIELD

The invention relates to a log wall structure defined in the preamble of claim 1.

BACKGROUND OF THE INVENTION

In comparison with traditional logs hewed from one tree, in the industrial production of log structures, several different log and log wall constructions are currently used, intended for improving the heat insulation capacity of the wall structure. Naturally, the insulation capacity is affected by the log thickness, and thick durable logs also can be manufactured by gluing from several parts. As is generally known, in addition to increasing the thickness of the log, the insulation capacity also can be improved by adding additional insulation in the wall structure. By using a water vapour permeable insulation layer inside the log, the heat insulation capacity of the structure can be improved without losing its natural breathing. Usually, a wall structure like this additionally includes a moisture permeable air barrier layer or vapour barrier to be fastened to a separate battening inside the additional insulation layer, and the inner wall surface itself. Typically, as an inner surface of this kind a panel is used but, however, as the surface, also any board is suitable which, depending on the situation, can be painted or wallpapered. In addition to giving a high heat insulation capacity, the flexible use of different inner wall surfaces, also in log construction, is enabled by the log structure in question, as an alternative for traditional logs.
In suitable conditions it is possible that, from the outside of the building, moisture penetrates into the insulation layer through the log joints, or moisture escaping from the inside of the building condensates on the log surface facing the additional insulation. If a situation like this occurs in practice, the water remaining in the wall can give rise to mould and structural damages.
Problems relating to moisture have been solved in the prior art by arranging a ventilating gap which is as continuous as possible between the log and the insulation. The moisture problem is thus solved, but according to building regulations the wall on the outer side of the continuous ventilating gap cannot be considered when calculating the total wall heat insulation capacity. Thus, the log wall on the outer side of the ventilating gap only serves as a load-bearing structure and an external cladding, and the heat insulation capacity of the wall must be achieved through insulation on the inner side of the air gap and the interior structures.
In publication DE 32 17 072 A1 , solution is disclosed where a continuous air space is created between a log and an insulation layer. Additionally, in publication US 2645824 the use of air flow in ventilating a wall is disclosed.

OBJECT OF THE INVENTION

The object of the invention is to eliminate the drawbacks mentioned above.
Particularly, it is an object of the invention to disclose a new kind of log wall structure, in which ventilation removing the moisture possibly condensing in the structure is realised in a very simple and advantageous way, while the heat insulation capacity of the log wall is utilised as efficiently as possible.

SUMMARY OF THE INVENTION

The log wall structure according to the invention is characterised by what is presented in claim 1.
A log wall structure according to the invention includes logs on top of each other. The logs to be used are preferably square logs but also round logs can be used. The structure also includes an insulation layer on the inner side of the log, and an inner wall surface covering the insulation layer. Additionally, the insulation layer may include a battening to which the inner wall surface has been fastened. In accordance with the invention, the construction contains essentially vertical spaced air channels at the interface log-insulation, for ventilating the wall structure.
The basic idea of the invention is a limited ventilation between the log and the insulation, that is, the air channels are not in contact with each other but, they clearly have a noticeable distance to each other. So, the log only is a little bit colder in the area of the air channels, and the heat insulation capacity of the log mainly remains unchanged. Air channels with appropriate spacing, however, are capable of sufficiently ventilating the inner log surface and to remove the excess moisture from the entire area thereof. Thus, the distances between the air channels preferably are in the range of 10 to 60 cm, e.g., approximately 30 cm, the width of the area free from air channels being in the same order, because the width of the air channel preferably is just a few centimetres.
Defining the invention by other terms, it can be stated that the distance between the air channels is multiple times, for example 5 to 10, even 20 times the width of the air channel. Thus, the cooling effect of the air flowing in the air channel on the total heat insulation capacity of the log wall is practically insignificant.
A log wall structure according to the invention also can be realised using a totally or partially load-bearing battening, in other words, also so that the wall structure has a vertical frame, to which the log coating forming the outer surface has been fastened. Thus, in the invention, log denotes a structure thicker than a board or panel structure, having a significant meaning for the heat insulation capacity of the entire wall. Thus, log thicknesses of more than 40 to 50 mm are usable for the invention.
Preferably, the wall structure also contains connecting channels extending from the interface log-insulation to the outer side of the wall, connecting the air channels with the air space on the outer side of the wall. In this way, the moisture possibly condensing in the wall structure can escape from the structure via air channels and connecting channels.
Preferably, for allowing free gravity ventilation, there are connecting channels both in the upper and lower parts of the wall. In a solution like this, gravity ventilation operates such that, in the air channels, a vertical flow is created due to gravity by the temperature of the air channels deviating from the air outside the wall structure. However, forced flow also can be used for intensifying the ventilation.
Preferably, the connecting channel is passing through the log. The channel can be easily machined directly into the log, and no channel-forming structures are needed for it, like a tube, since the log itself acts as a supporting structure forming a free channel. If needed, the opening of the connecting channel can be covered with a grid or a net preventing birds or small animals from getting into the channels. Naturally, it also is possible for the connecting channels to begin beneath the lowermost log from the outer space and/or to end up above the uppermost log in the outer space, thereupon not passing through the log.
The structure forming the air channel preferably includes an elongated water vapour permeable strip set against the log and/or the vertical battening for the insulation layer. This strip, either alone or together with the log and/or battening surface, forms the air channel in question. The strip itself preferably is made of a water vapour permeable material. It also is possible to use some perforated, as such water vapour impermeable material. Preferably, the material of the strip also is so soft and elastic that, notwithstanding the possible lowering and deformations of the logs, the air channel remains non-clogged and non-broken. A preferable material is, for example, cardboard. Several strips forming an air channel also may be connected to a single board-like structure.
Preferably, the elongated strip includes flanges for fastening thereof to the log and/or the battening, and an intermediate part between the flanges, together with the mounting base, forming an air channel. The cross-sectional form of the intermediate part can be angular or curved. It is essential that it is separated from the mounting base of the strip. The flanges preferably extend over the entire length of the strip. Thus, in addition to acting as a fixing point, they prevent the channel from being clogged, for example, upon applying loose insulation material by blowing or spraying.
The strip of material permeable to water vapour, tube or channel, whether it has a closed or an open cross-section facing the log, may have a square, triangle, round or whatsoever cross-section.
Furthermore, in a log wall structure according to the invention, between adjacent air channels, the horizontal groove at the joint of two logs on top of each other preferably is coated with a water vapour permeable strip. Thus, the groove covered by the strip forms an intermediate channel interconnecting the adjacent air channels. In this way, by arranging several intermediate channels in the structure, a network of horizontal and vertical ventilation channels may be provided.
At the surface of a board-like insulation to be mounted against the log surface, the structure forming the air channel also can contain an elongated groove which, together with the log surface, forms the air channel. The groove also can be made as a chamfer in the edge of the insulation board to be mounted against the juncture between the log surface and the battening, the air channel thereby being formed together by the chamfer, the log surface and the battening.
In a log wall structure according to the invention, the sizes and numbers of the air, connecting and intermediate channels may vary depending on the situation and the need for ventilation. When estimating the need for ventilation, empiric observations as well as physical modelling can be utilised.
The log wall structure according to the invention mainly has been developed for structures without vapour barrier but nothing prevents from using it also in walls provided with vapour barrier, since moisture entering the structure is removed by the invention regardless of the direction in which the moisture enters. Thus, in the inventive structure, more or less breathing insulations may be used, like cellulose wool, glass wool, mineral wool, polyurethane, sawdust, other wood fibre insulations etc. depending on the circumstances. It also is possible that, on the inner surface of the log, a breathing windshield is used, like paper or cardboard, on which the vertical air channels then are mounted. Likewise, on top of the insulation, on the inner side of the structure, the vapour barrier already mentioned or a water vapour permeable constructing cardboard may be used as an air barrier layer.
The log wall structure according to the invention has remarkable advantages over prior art. In the invention, providing the ventilation for the wall structure has been accomplished in a very simple way requiring a few working steps and little costs, which also is well applicable for do-it-yourself building. The strips and flaps forming the necessary air channels and intermediate channels may be present, for example, as a cardboard roll which is easy to handle and lightweight, from which they are cut to desired length. It also is possible to use sheets and strips of cardboard or other material already being provided with creases, so that in the mounting stage, the channel can easily be folded or bent to proper form. Additionally, the simplicity and the cheapness of the structure are increased by the fact that the channels extend at the surface of the log, in other words, there is no need for machining forms in the surfaces of the logs, required by the structure. So, for the inventive structure, all existing log frames and those manufactured by the modern techniques and know-how are applicable as such. Depending on the structures, only at the upper and lower ends of the wall, channels extending through the log may be necessary.
A log wall structure according to the invention also is very versatile. The solution according to the invention can be utilised both in a settling traditional log wall and a non-settling wall structure. Neither is the log profile critical, the logs may be both square and round logs. In a structure without vapour barrier, the most important feature required of the insulation is permeability to water vapour but, for the rest, insulations inserted by blowing or spraying and board-like insulations may both be used in the inventive wall structure. So as to be suitable for each situation, the efficiency of the ventilation may be adjusted by the size and number of the air channels, while considering the climate type in the region, the log and insulation thicknesses, and other physical properties, the conditions prevailing in the building, and other factors influencing the condensation of moisture and need for ventilation.

LIST OF DRAWINGS

In the following, the invention is described in detail by means of embodiments, referring to the attached drawings, in which

Fig. 1 shows a horizontal cross-section of a log wall structure according to the invention, as seen from above or below,
Fig. 2 shows a vertical cross-section of a log wall structure according to the invention, seen in the direction of the wall,
Fig. 3 shows an alternative for an elongated strip belonging to a structure forming the air channel,
Fig. 4 shows a vertical cross-section of a log wall structure according to the invention at the interface log-insulation, in the longitudinal direction of the wall, as seen from the side, and
Fig. 5 shows a board-like insulation belonging to a log wall structure according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

A log wall structure according to the invention shown cross-sectionally in Fig. 1 contains as the outermost layer a log 1. On the inner side of the log, there is an insulation layer 2 and an inner wall surface 3 covering it. The material of the insulation layer is water vapour permeable so as to guarantee breathing of the structure. As such an insulation material, for example, cellulose wool is used. On top of the insulation 2, that is, under the inner wall surface 3, there is an air barrier layer 14 permeable to moisture in this embodiment. Instead, also a vapour barrier can be used, if required by the insulations and other wall structures employed. For maintaining the insulation in position and fastening the inner wall surface, the insulation layer also is provided with a battening 6. At the interface log-insulation, there are essentially vertically mounted strips 7 permeable to water vapour, set against the log and/or the battening at a distance from each other. Together with their mounting base, the strips form essentially vertical air channels 4 at the interface in order to ventilate the structure. The distance of the channels from each other is noticeably greater than the width of a single channel.
In the cross-section of Fig. 2 also an embodiment is shown for connecting channels 5 connecting the air channel 4 with the air space on the outer side of the wall. From the interface log-insulation, they pass to the outer side of the wall straight through the logs 1. By using a solution according to the figure having connecting channels both in the upper and the lower parts of the wall, free gravity ventilation is enabled in the channels. The function is based on the fact that, in the air channels 4 inside the wall structure, the air has a different temperature than the air on the outer side of the wall structure. By the gravity, a vertical air flow is then created in the channels, effectively transporting away moisture possibly condensed in the structure.
The strip 7 of Fig. 3 for forming the air channel is provided with flanges 8 for fastening thereof to the log and/or to the vertical battening for the insulation layer. Fastening can be accomplished, for example, by rivets or by gluing. The strip also includes an intermediate part 9 remaining after installation elevated from the mounting base and forming therewith an air channel free from insulation. In the figure, a simple solution is shown, in which the folds of the strip form a channel structure with triangular cross-section. Other forms also are possible; the cross-section of the intermediate part 9 can be, for example, rectangular or curved. In the same way, the intermediate part 9 can be a closed tube as such without flanges 8 or provided with them. The strip 7 is set in place before the insulation. So, an insulation material in bulk, to be mounted, for example, by blowing or injecting can be used without clogging the air channel 4. For the flanges, it is not necessary that they are as long as the entire strip but, by using strips with full length, the channels are more effectively protected against clogging.
The strip 7 is water vapour permeable. It can be made of a material as such permeable to water vapour, for example, cardboard but, in principle, also some perforated material as such impermeable to water vapour can be used. When manufacturing of cardboard, the strips also are lightweight, and they can be made to a roll easy to handle and requiring little space, from which it is easy to cut them to desired size on site.
The embodiment according to the invention shown in Fig. 4 includes a water vapour permeable flap 11 covering the horizontal groove 10 at the joint of logs 1 on top of each other between the adjacent strips. In the figure, for the sake of exemplification, it only is drawn for a part of the distance. In the figure, the air channels 4 remain under the strips 7. Together with the groove at the joint between the logs, the flap 11 forms an intermediate channel connecting the air channels, free from insulation, remaining in Fig. 4 under the flap. By the intermediate channels, the ventilation is intensified and, by adding them to the structure, an entire network of horizontal and vertical ventilation channels can be formed. In the figure, rivets also can be seen in the flanges of the right-hand strip 7 used for fastening the strip to the logs 1.
As an alternative for the insulation layer 4, a board-like water vapour permeable insulation 12 is shown in Fig. 5, having a substantially vertical groove 13 at the surface to be mounted against the logs. Together with the log surface, the groove forms an air channel 4 required for ventilation. The groove also can be accomplished as a chamfer in the edge of the insulation board to be mounted against the joint between the log and the battening, the air channel then being formed together by the chamfer, the log and the battening.

Claims

A log wall structure including at least one log (1), an insulation layer (2) on the inner side of the log, and an inner wall surface (3) covering the insulation layer, characterized in that the interface log-insulation contains substantially vertical spaced air channels (4) for ventilating the wall structure and, between the air channels, there is a region free from air channels, having a width that is multiple times the width of one air channel.
A log wall structure according to claim 1, characterized in that the structure includes connecting channels (5) extending from the interface between the log (1) and the insulation (2) to the outer side of the wall, allowing the air channels (4) to communicate with the air space on the outer side of the wall structure.
A log wall structure according to claim 2, characterized in that there are connecting channels (5) both in the upper and the lower parts of the wall in order to enable free gravity ventilation.
A log wall structure according to claim 2 or 3, characterized in that the connecting channel passes through the log (1).
A log wall structure according to claim 1, characterized in that the structure forming the air channel contains an elongated water vapour permeable strip (7) mounted against the log (1) and/or a vertical battening (6) of the insulation layer; wherein the strip (7) is open or closed on the side of the log.
A log wall structure according to claim 5, characterized in that the strip (7) includes flanges (8) for fastening it to the log and/or to the vertical battening of the insulation layer, as well as an intermediate part (9) between the flanges elevated from a mounting base, forming an air channel together with the mounting base.
A log wall structure according to any of the claims 1 to 6, characterized in that the substantially horizontal groove (10) formed at the joint of two logs when these are on top of each other, over the distance between the adjacent air channels, is covered by a water vapour permeable flap (11) in order to form an intermediate channel connecting the air channels.
A log wall structure according to claim 1, characterized in that, the insulation layer (2) comprises a board-like insulation (12) to be mounted against the log surface, wherein at the surface of the insulation, the structure forming the air channel (4) includes a substantially vertical groove (13).
A log wall structure according to any of the claims 1 to 8, characterized in that the vertical air channels are spaced from each other by 10 to 60, preferably 20 to 40, for example, approximately 30 cm.
A log wall structure according to claim 1, characterized in that the distance between the air channels is more than 5 times, preferably approximately 10 times and even 20 times the width of one air channel.
A log wall structure according to any of the claims 1 to 9, characterized in that, on top of the insulation layer (2), depending on the insulation used, an air barrier layer (14) or a vapour barrier is provided.