Condensation prevention structure for exterior walls

Abstract

To provide an exterior wall condensation prevention structure that minimizes constraints on the selection of constituent materials. [Solution] The exterior wall (1) is constructed by laminating an exterior material (4), a ventilation layer (3), an insulation layer (2), and an interior material (6) in order from the outdoor (S2) side to the indoor (S1) side, and comprises a moisture-proof means (8) provided between the insulation layer and the interior material to block the inflow of moisture from both the outdoor and indoor sides, and a moisture permeability adjustment means (9) positioned between the insulation layer and the ventilation layer to adjust the amount of moisture permeation from the outdoor side to the indoor side to be less than the amount of moisture permeation from the indoor side to the outdoor side.

Description

[Technical Field]

[0001] The present invention relates to a dew-proof structure for preventing dew condensation inside an outer wall. [Background Art]

[0002] As structures for preventing dew condensation inside the outer wall of a building (such as a house), for example, the outer wall structure described in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2012-233296) and the moisture-proof and air-tight panel described in Patent Document 2 (Japanese Unexamined Patent Application Publication No. 9-53282) are known.

[0003] The outer wall structure described in Patent Document 1 includes a moisture-proof layer disposed on the outdoor side of a heat insulating material, an interior material disposed on the indoor side of the heat insulating material, an inner surface material disposed on the indoor side of the interior material via an inner ventilation layer, and an interior finish material affixed to the indoor side of the inner surface material. By defining the moisture permeability resistance ratio of the moisture permeability resistance A of the moisture-proof layer, the moisture permeability resistance B of the interior material, and the moisture permeability resistance C of the inner surface material including the interior finish material, the object of the invention is to provide an outer wall structure that can effectively prevent summer-type dew condensation.

[0004] In the moisture-proof and air-tight panel described in Patent Document 2, heat insulating layers are provided inward and outward within the outer wall of a wooden building with the moisture-proof and air-tight layer as a boundary, and the thermal resistance ratio of the inward and outward heat insulating layers is determined based on the physical properties of the constituent members so that the internal environment of the panel achieves desired temperature and relative humidity during winter heating and summer cooling, respectively. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2012-233296 (Patent No. 5806499) [Patent Document 2] Japanese Unexamined Patent Application Publication No. 9-53282 [Summary of the Invention] [Problem to be Solved by the Invention]

[0006] The exterior wall structure described in Patent Document 1 specifies the ratio of water vapor permeability resistance between its constituent members. Therefore, if the thickness of a part of the constituent member (for example, interior material) is increased to improve its thermal insulation performance, the ratio of water vapor permeability resistance changes, and it may no longer perform the intended function. In other words, there is a limitation on the degree of freedom in selecting constituent members. Similarly, the moisture-proof and airtight panel described in Patent Document 2 also specifies the ratio of thermal resistance between its constituent members, thus limiting the selection of constituent members.

[0007] The present invention was made to solve the above-mentioned problems, and its objective is to provide an exterior wall condensation prevention structure that minimizes the constraints on the selection of constituent materials. [Means for solving the problem]

[0008] The condensation prevention structure for an exterior wall according to the present invention is a condensation prevention structure for an exterior wall in which an exterior material, a ventilation layer, an insulation layer, and an interior material are laminated in order from the outside to the inside, and comprises a moisture-proof means provided between the insulation layer and the interior material to block the inflow of moisture from both the outside and the inside, and a moisture permeability adjusting means arranged between the insulation layer and the ventilation layer to adjust the amount of moisture permeation from the outside to the inside to be less than the amount of moisture permeation from the inside to the outside.

[0009] Preferably, the moisture permeability adjustment means increases the moisture permeability resistance when the outside air is hot or humid, and decreases the moisture permeability resistance when the outside air is cold or humid.

[0010] Preferably, the moisture permeability adjustment means is composed of a moisture-permeable variable sheet having a large number of micropores, the opening ratio of which is variable according to temperature or humidity, so that when the temperature or humidity of the outside air is high, the moisture resistance increases as the micropores become smaller, and when the temperature or humidity of the outside air is low, the moisture resistance decreases as the micropores become larger.

[0011] Preferably, the insulation layer includes a board-shaped insulation material placed on the exterior side and a cotton-like insulation material placed on the interior side of the board-shaped insulation material, and the moisture permeability adjustment means is sandwiched between the board-shaped insulation material and the cotton-like insulation material.

[0012] Preferably, the thermal insulation layer and the interior material are spaced apart from each other, forming an air layer between them, and the moisture barrier is a sheet material provided on the interior material so as to face the air layer. [Effects of the Invention]

[0013] According to the present invention, since the amount of moisture that permeates the exterior wall to the inside and outside is adjusted by the moisture permeability adjustment means, the constraints on the selection of constituent materials can be minimized. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic cross-sectional view showing the condensation prevention structure of the exterior wall according to this embodiment. [Figure 2] This figure schematically illustrates the function of the sheet member according to this embodiment. [Figure 3] This graph shows the relative water vapor resistance of various sheets. [Figure 4] This is a schematic cross-sectional view showing the condensation prevention structure of the exterior wall according to this embodiment during winter. [Figure 5] This is a schematic cross-sectional view showing the condensation prevention structure of the exterior wall according to this embodiment during the summer. [Figure 6] (A) is a schematic cross-sectional view illustrating winter condensation within an exterior wall, and (B) is a schematic cross-sectional view illustrating a conventional example of countermeasures against winter condensation. [Figure 7] This is a schematic cross-sectional view illustrating summer condensation within an exterior wall. [Figure 8] (A) is a schematic cross-sectional view illustrating another conventional countermeasure for summer condensation, and (B) is a schematic cross-sectional view illustrating another conventional countermeasure for winter condensation. [Modes for carrying out the invention]

[0015] Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0016] <Types of Condensation and Conventional Countermeasure Examples> Before describing the dew-proof structure for an exterior wall according to the present embodiment, the causes of condensation occurring inside a known exterior wall 101 and the like, and conventional countermeasure examples will be described with reference to FIGS. 6 to 8.

[0017] In FIG. 6 and the like, the indoor side of the exterior wall 101 and the like is denoted by reference sign S1, and the outdoor side is denoted by reference sign S2. The exterior wall 101 includes a heat insulating layer 2, a ventilation layer 3 formed on the outdoor side of the heat insulating layer 2, and an exterior cladding material 4 disposed on the outdoor side of the ventilation layer 3. The exterior wall 101 also includes an air layer 5 formed on the indoor side of the heat insulating layer 2, an interior material 6 (gypsum board) disposed on the indoor side of the air layer 5, and a finishing material 7 (indicated by a thick line) applied to the indoor-side surface of the interior material 6.

[0018] The heat insulating layer 2 includes a board-shaped heat insulating material 21 on the outdoor side, and a cotton-shaped heat insulating material 22 disposed more on the indoor side than the board-shaped heat insulating material 21. Note that the ventilation layer 3 is a space through which outside air flows upward from below, and serves to ventilate the inside of the exterior wall 101.

[0019] FIG. 6(A) is a diagram showing how winter-type condensation occurs inside the exterior wall 101. This figure shows the interior of the exterior wall 101 during a period when outside air is low in temperature and humidity, such as winter. On the other hand, air in the indoor space may become warm and highly humid due to moisture emitted by the human body, daily activities such as cooking, and the use of gas heaters, humidifiers, or the like. In this case, when warm moisture M flows into the exterior wall 101 from the indoor space, it contacts the low-temperature heat insulating material 21 adjacent to the ventilation layer 3, is cooled, and condensation Ms occurs (winter-type condensation).

[0020] FIG. 6(B) is a diagram showing a countermeasure for the above-described winter-type condensation. A moisture-proof sheet 8 that blocks moisture is affixed to the back surface side of the interior material 6. The moisture M from the indoor space is prevented by the moisture-proof sheet 8 from flowing further toward the outdoor side. Therefore, the moisture M can be prevented from contacting the cooled heat insulating material 21, which serves as a countermeasure against winter-type condensation.

[0021] While installing the moisture barrier sheet 8 is effective in preventing winter condensation, it may cause summer condensation. The reason for this will be explained with reference to Figure 7. Figure 7 shows the interior of the exterior wall 102 during periods of high temperature and humidity, such as summer.

[0022] High-temperature moisture M flows from the outside into the exterior wall 102 and, as it flows towards the inside, reaches the vapor barrier 8. The vapor barrier 8 is impermeable to moisture and is also at a low temperature due to the air conditioning in the indoor space. Therefore, the high-temperature moisture M that comes into contact with the vapor barrier 8 is cooled, and condensation Ms occurs on the outdoor surface of the vapor barrier 8 (summer condensation).

[0023] As a means of addressing both winter and summer condensation, it is conceivable to install a sheet within the exterior wall 1 whose vapor permeability resistance changes according to the relative humidity. An example of such a sheet is "Isover Vario Extra Safe" manufactured by Mag Isover Co., Ltd. (hereinafter referred to as the "humidity control sheet").

[0024] It is believed that moisture-regulating sheets exhibit moisture-proof properties in environments with low humidity and low relative humidity, as the molecular structure of the sheet becomes uniform, leaving no gaps for moisture to pass through. On the other hand, in environments with high humidity and high relative humidity, the molecules bond together, creating gaps for moisture to pass through, thus exhibiting moisture-permeable properties.

[0025] Referring to Figure 8, an example of condensation prevention using the above-mentioned humidity control sheet will be explained. The humidity control sheet E is attached to the back surface of the interior material 6 in place of the moisture barrier sheet 8.

[0026] Figure 8(A) shows the interior of the exterior wall 103 during periods of high temperature and humidity, such as summer. High-temperature moisture M flows into the exterior wall 103 from the outside and, as it flows towards the inside, reaches the humidity control sheet E. Because the inside of the exterior wall 103 is a humid environment with high relative humidity, gaps D1 are created in the humidity control sheet E that allow moisture to pass through. As a result, moisture M can pass through the humidity control sheet E and escape into the indoor space, preventing summer condensation.

[0027] On the other hand, Figure 8(B) shows the interior of the exterior wall 103 during periods of low temperature and low humidity, such as winter. Inside the exterior wall 103, there is little moisture and the relative humidity is low, so the gap D2 in the humidity control sheet E is small enough to prevent moisture M from passing through. As a result, the flow of warm moisture M from the indoor space to the indoor side is blocked by the humidity control sheet E, preventing winter condensation.

[0028] While using the humidity control sheet E can mitigate both winter and summer condensation, it restricts the choice of finishing material 7. Specifically, to combat summer condensation, the finishing material 7 must be a material that allows moisture M to pass through (such as paper wallpaper). Therefore, materials that do not allow (or allow very little) moisture M to pass through, such as vinyl wallpaper, cannot be used as finishing material 7. Since the finishing material 7 faces the interior space and plays an important role in directly affecting the visual impression, a wide range of choices is desirable.

[0029] In contrast, the condensation prevention structure of the exterior wall 1 according to this embodiment, which will be described below with reference to Figures 1 to 5, can prevent both winter and summer condensation, regardless of the material of the finishing material 7.

[0030] <Embodiment> Referring to Figure 1, the internal structure of the exterior wall 1 according to this embodiment will be described. The exterior wall 1 is constructed by laminating exterior material 4, a ventilation layer 3, an insulation layer 2, and interior material 6 (for example, gypsum board) in order from the outdoor side to the indoor side. The exterior material 4 and the ventilation layer 3 are adjacent to each other, and the ventilation layer 3 and the insulation layer 2 are adjacent to each other. The insulation layer 2 and the interior material 6 are spaced apart from each other, and an air layer 5 is formed between them. The air layer 5 is expected to provide heat retention effects for both cooling and heating.

[0031] A moisture barrier sheet 8 (an example of a moisture barrier) is provided between the insulation layer 2 and the interior material 6 to block the inflow of moisture from both the outdoor and indoor sides. In this embodiment, similar to the exterior wall 102 described above, the moisture barrier sheet 8 is attached to the back surface of the interior material 6 so as to face the air layer 5. A finishing material 7 (shown by a thick line) is applied to the surface of the interior material 6.

[0032] The insulation layer 2 consists of a board-shaped insulation material 21 placed on the exterior side and a cotton-like insulation material 22 placed on the interior side of the board-shaped insulation material 21. The board-shaped insulation material 21 is, for example, a high-density glass wool board (12 mm thick, 140 kg / m³ density). 3 The cotton-like insulation material 22 is, for example, made up of two layers of high-performance glass wool (approximately 60 mm thick).

[0033] (Moisture-permeable variable sheet) A variable vapor permeability sheet 9 (an example of a vapor permeability adjustment means), shown in light gray, is placed between the ventilation layer 3 and the insulation layer 2. Specifically, the variable vapor permeability sheet 9 is sandwiched between the insulation material 21 and the insulation material 22. Note that the thickness of the variable vapor permeability sheet 9 is exaggerated. The variable vapor permeability sheet 9 has high vapor permeability resistance when the outside air is hot or humid, and low vapor permeability resistance when the outside air is cold or humid. For example, the vapor permeability resistance may be low up to an outside air temperature of about 15°C, and high when the outside air temperature is 20°C or higher.

[0034] Referring to Figure 2, an example of the variable moisture permeability sheet 9 will be described. The variable moisture permeability sheet 9 is, for example, a single-layer sheet made of a thermally expanding material, and has a large number of micropores H formed on it. Note that the size of the micropores H is exaggerated.

[0035] The moisture-permeable variable sheet 9 changes its opening ratio depending on the temperature. Specifically, as shown by the micropores H in the upper right of the page of the moisture-permeable variable sheet 9, when the outside air is cold, the micropores H become larger (symbol h1), making them larger and allowing moisture to pass through more easily. In other words, the moisture resistance decreases at lower temperatures. On the other hand, when the outside air is hot, the micropores H become smaller (symbol h2), making them larger and making it more difficult for moisture to pass through. In other words, the moisture resistance increases at higher temperatures.

[0036] Furthermore, the variable moisture permeability sheet 9 may be a single-layer sheet whose moisture permeability resistance changes depending on the humidity. For example, it may be a sheet that has the opposite effect to the moisture control sheet E (Isover Vario Extra Safe) described above.

[0037] Specifically, in environments with low ambient humidity and low relative humidity, the molecules constituting the variable moisture permeability sheet 9 bond together, increasing the gaps (micropores H) between the molecular structures (symbol h1). In this case, the opening ratio of the variable moisture permeability sheet 9 increases, allowing moisture to pass through (the moisture resistance decreases).

[0038] On the other hand, in environments with high humidity and high relative humidity, the molecular structure constituting the variable vapor permeability sheet 9 becomes uniform, and the gaps through which moisture can pass become smaller (symbol h2). In this case, the opening ratio of the variable vapor permeability sheet 9 becomes smaller, making it more difficult for moisture to pass through (the vapor permeability resistance increases).

[0039] Figure 3 is a graph showing a comparative example of the moisture permeability resistance of the variable moisture permeability sheet 9, whose moisture permeability resistance changes depending on humidity, and the moisture permeability resistances of the humidity control sheet E, the moisture-blocking moisture barrier sheet 8, and a general moisture-permeable sheet that allows moisture to pass through. As described above, the variable moisture permeability sheet 9 exhibits characteristics opposite to those of the humidity control sheet E. When the relative humidity is around 50% or less, the variable moisture permeability sheet 9 has a lower moisture permeability resistance than the moisture-permeable sheet. When the relative humidity exceeds 50%, the moisture permeability resistance increases sharply, and when it exceeds around 70%, the moisture permeability resistance becomes as high as that of the moisture barrier sheet 8.

[0040] (Winter condensation countermeasures) Referring to Figure 4, the winter condensation countermeasures for the exterior wall 1 according to this embodiment will be explained. Figure 4 shows the interior of the exterior wall 1 during periods when the outside air is cold and humid, such as in winter. When moisture M flows into the exterior wall 1 from the indoor space, the moisture barrier sheet 8, which blocks moisture, prevents further inflow of moisture M to the outside.

[0041] Even if a small amount of moisture M were to pass through the vapor barrier sheet 8, because the outside air is cold (or low humidity), the micropores H of the variable vapor permeability sheet 9 are large enough (h1) to allow moisture to pass through, and the vapor resistance of the variable vapor permeability sheet 9 is small. Therefore, the moisture M passes through the variable vapor permeability sheet 9, flows into the ventilation layer 3, and is discharged to the outside from the ventilation layer 3. In this way, the moisture M does not accumulate inside the exterior wall 1, and winter condensation is prevented.

[0042] (Summer condensation countermeasures) Referring to Figure 5, the countermeasures against summer condensation in the exterior wall 1 according to this embodiment will be explained. Figure 5 shows the interior of the exterior wall 1 during a period when the outside air is hot and humid, such as in summer. Moisture M that flows into the exterior wall 1 from the outside reaches the moisture-permeable sheet 9. Because the outside air is hot (or humid), the micropores H of the moisture-permeable sheet 9 are of a size (h2) that makes it difficult for moisture to pass through, and the moisture resistance of the moisture-permeable sheet 9 is large. Therefore, the amount of moisture M that passes through the moisture-permeable sheet 9 is minimized. Since the amount of moisture M that passes through the moisture-permeable sheet 9 and reaches the moisture-proof sheet 8 is greatly reduced, the occurrence of summer condensation is suppressed.

[0043] (advantage) According to the condensation-preventing structure of the exterior wall 1 in this embodiment, the moisture permeability resistance within the exterior wall 1 is adjusted by the moisture permeability variable sheet 9, thus realizing a condensation-preventing structure that is less affected by the thermal insulation performance of the constituent members of the exterior wall 1. Since there are many options for the constituent members of the exterior wall 1, it can be adopted in a wide range of structures, regardless of whether they are steel-framed or wooden.

[0044] Furthermore, the combination of the variable-permeability sheet 9 and the vapor barrier sheet 8 provides protection against condensation in both winter and summer, reducing the risk of internal condensation in the exterior wall 1 regardless of the season. Additionally, since the vapor barrier sheet 8 is attached to the back of the interior material 6, the material of the finishing material 7 on the surface of the interior material 6 can be freely selected without worrying about its breathability.

[0045] (others) In this embodiment, examples have been described in which the micropores H deform in both expansion (h1) and contraction (h2), but the micropores H may deform only in contraction (or expansion). That is, the micropores H may be formed to a size that allows moisture to pass through, and contract when the temperature is high or the humidity is high (increasing moisture resistance), and return to their original size when the temperature is low or the humidity is low (decreasing moisture resistance). Alternatively, the micropores H may be formed to a size that does not allow moisture to pass through, and expand when the temperature is low or the humidity is low (decreasing moisture resistance), and return to their original size when the temperature is high or the humidity is high (increasing moisture resistance). For example, the variable moisture permeability sheet 9 may be made of a heat-shrinkable material (for example, polyvinyl chloride or nonwoven fabric).

[0046] Furthermore, although the cotton-like insulation material 22 is provided in two layers, it may be provided in two or more layers (for example, three layers). Also, from the viewpoint of ease of installation, it is desirable to sandwich the vapor-permeable sheet 9 between the insulation material 21 and the insulation material 22, but this is not limited, and it may be provided on the outdoor side of the board-shaped insulation material 21 (the side facing the ventilation layer 3). In other words, when the vapor-permeable sheet 9 is "placed between the insulation layer and the ventilation layer," it includes not only the case where it is placed between the insulation materials that make up the insulation layer 2, but also the case where it is placed on the outermost surface of the insulation layer 2.

[0047] Furthermore, when a variable vapor permeability sheet 9, whose vapor permeability resistance changes depending on the temperature, is sandwiched between the insulation material 21 and the insulation material 22, it is desirable that the thermal resistance value of the insulation material 21 be 10% or less of the thermal resistance value of the entire insulation layer 2 (both insulation materials 21 and 22) so that the variable vapor permeability sheet 9 can react.

[0048] In this embodiment, a moisture-permeable variable sheet 9 whose structure changes according to temperature or humidity is given as an example, but an opening may be provided in the sheet material or board material and the opening may be physically opened and closed with a damper.

[0049] Alternatively, for example, a two-layer sheet could be constructed by layering an outdoor sheet with numerous fine slits and an indoor sheet that allows moisture to pass through. In winter, when moisture flows from indoors to outdoors, it can pass through the slits, but in summer, when moisture flows from outdoors to indoors, it can be prevented from passing through the slits, similar to a check valve.

[0050] Although embodiments of this invention have been described above with reference to the drawings, this invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiments within the same scope as this invention, or within the equivalent scope. [Explanation of Symbols]

[0051] 1. Exterior wall, 2. Insulation layer, 3. Ventilation layer, 4. Exterior cladding, 5. Air layer, 6. Interior cladding, 7. Finishing material, 8. Moisture barrier sheet, 9. Moisture-permeable variable sheet. M Moisture

Claims

1. An exterior wall condensation prevention structure in which an exterior material, a ventilation layer, an insulation layer, and an interior material are layered in order from the exterior side to the interior side, A moisture-proof means is provided between the insulation layer and the interior material to block the inflow of moisture from both the outdoor and indoor sides, A condensation-preventing structure for an exterior wall, comprising a moisture permeability adjustment means disposed between the insulation layer and the ventilation layer, which adjusts the amount of moisture permeation from the outdoor side to the indoor side to be less than the amount of moisture permeation from the indoor side to the outdoor side.

2. The moisture permeability adjustment means increases the moisture permeability resistance when the outside air is hot or humid, and decreases the moisture permeability resistance when the outside air is cold or humid, as described in claim 1, for an exterior wall condensation prevention structure.

3. The moisture permeability adjustment means is composed of a moisture-permeable variable sheet having numerous micropores, the opening ratio of which is variable depending on the temperature or humidity. The condensation-preventing structure for an exterior wall according to claim 2, wherein when the temperature or humidity of the outside air is high, the micropores become smaller, increasing the resistance to water permeability, and when the temperature or humidity of the outside air is low, the micropores become larger, decreasing the resistance to water permeability.

4. The aforementioned insulation layer includes a board-shaped insulation material placed on the exterior side and a cotton-like insulation material placed on the interior side of the board-shaped insulation material. The moisture permeability adjustment means is sandwiched between the board-shaped insulation material and the cotton-like insulation material, as described in claim 1, for the condensation prevention structure of an exterior wall.

5. The aforementioned insulation layer and the aforementioned interior material are arranged spaced apart from each other, and an air layer is formed between them. The moisture-proofing means is a sheet material, which is provided on the interior material so as to face the air layer, in the condensation-proofing structure for an exterior wall according to claim 1.

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