JPH0431377A - Moisture condensation-preventing structure forming space - Google Patents

Abstract

PURPOSE:To prevent the development of moisture condensation by forming a thermal insulating layer of specified composition, through wet application, on the space side surface of a concrete substrate and also forming a moisture-absorptive and emissive layer on the space side surface of said thermal insulating layer. CONSTITUTION:Firstly, a mixture for thermal insulating materials is prepared by incorporating and kneading (A) 100 pts.wt. of cement with (B) 3-50 pts.wt., on a solid basis, of a synthetic resin emulsion such as acrylic one, (C) 1-20 pts.wt. of organic microballoons 10-100mum in size and <=0.04 in specific gravity, (D) 0.3-5 pts.wt. of carbon fiber ca.6mm in length, (E) 10-200 pts.wt. of inorganic microballoons 5-200mum in size and 0.3-0.7 in specific gravity, (F) such ingredients as thickening agent, antifoaming agent and antifungal agent, and (G) water. Second, this mixture is put to wet application on the surface of the space 33 side of a concrete substrate 35 to form a thermal insulating layer 37 10-15mm thick. Thence, a moisture-absorptive and emissive layer 39 capable of absorbing moisture under high-humidity conditions and spontaneously releasing it under low-humidity conditions is formed on the surface of the space 33 side of this thermal insulating layer 37, thus obtaining the objective moisture condensation-preventing structure 31.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a dew condensation prevention structure that forms a space.

[Conventional technology]

BACKGROUND ART Conventionally, for example, in highly airtight rooms such as apartments and hotels, the humidity increases due to the use of a stove or the like in the room, which may cause discomfort to humans.

Therefore, in order to create an indoor space that is comfortable for humans, condensation prevention structures such as walls and ceilings have been developed that appropriately adjust the humidity in the indoor space and suppress the occurrence of condensation.

FIG. 2 shows a dew condensation prevention structure that forms such a space, and reference numeral 11 indicates a dew condensation prevention structure that includes a wall that forms a space 13. As shown in FIG.

This dew condensation prevention structure 11 is formed of a concrete base 15. A heat insulating layer 17 is formed on the surface of the 13 spaces of this concrete base 15, and this insulating layer 1
A flame-retardant gypsum board 19 is adhered to the surface of the 13 spaces of No. 7 by means of pounds 18.

A hygroscopic layer 21 is formed on the surface of the gypsum board 19 on the side of the space 13, which absorbs moisture when the humidity in the space 13 is high and naturally releases moisture when the humidity is low.
1 is formed, for example, by pasting wallpaper that can retain moisture at 200 to 300 g/nf. Also,
In order to impart moisture absorption and release properties to the wallpaper with two moisture absorption and release layers, it is constructed in combination with a material that has moisture absorption and release properties, such as a super absorbent polymer.

The heat insulating layer 17 is made of an organic heat insulating material such as urethane foam or styrofoam.

In the dew condensation prevention structure forming the space configured as described above, the heat insulating layer 17 blocks heat from the outside, and the moisture in the space 13 can be adjusted by the moisture absorbing and releasing layer 21. The humidity in the space 13 can be maintained at a state comfortable for humans, and the occurrence of dew condensation can be suppressed.

[Problems to be Solved by the Invention] However, organic heat insulating materials such as urethane foam and styrofoam forming the heat insulating layer 17 have a thermal conductivity of 0.0.
2 to 0.03 (kcal/mhr''C), which is very small, and therefore exhibits excellent heat insulation performance, but because it is organic, it has the problem of being easily flammable.

For this reason, due to legal restrictions and strength issues regarding fire prevention, for example, flame-retardant gypsum board 19 is pasted on the surface of the 13 spaces of the heat insulating layer 17, and this is used as a base for absorbing absorbent material made of wallpaper. It is necessary to form the moisture releasing layer 21, which increases the number of construction steps, takes time and effort, and causes problems in that the space 13 is narrowed.

In order to solve these problems, it is conceivable to form the heat insulating layer 17 with an inorganic heat insulating material such as foamed mortar or perlite mortar.

Such inorganic insulation materials have the property of being difficult to burn, but their thermal conductivity ranges from 0.2 to O63 (kcal/mhr).
"C), an organic heat insulating material (0.02~0.03k
cal/mhr″C), it is very large compared to
There was a problem that the insulation performance was inferior compared to organic insulation materials.

For this reason, it is not only difficult to secure the desired heat insulation performance, but also a considerable thickness is required to ensure that performance.

Furthermore, when attempting to improve the heat insulating performance of such inorganic heat insulating materials, there is a problem in that the strength becomes extremely weak and the material cannot function as a finishing base.

The present invention was made to solve the above-mentioned problems, and has heat insulation performance close to that of organic heat insulating materials, and from the viewpoint of flame retardancy, it is superior to conventional inorganic heat insulating materials. By using a heat insulating material that has the performance of
By using this heat insulating layer as a direct base and forming a moisture absorbing and releasing layer that also serves as makeup on top, it has the function of adjusting the humidity in the space to a comfortable state and reliably prevents condensation. An object of the present invention is to provide a structure for preventing dew condensation that forms a space in which the dew condensation can be prevented.

[Means to solve the problem]

The structure for preventing dew condensation forming a space according to claim 1 includes forming a heat insulating layer on a surface of a concrete base forming the space on the side of the space, and forming a heat insulating layer on a surface of the space on the side of the space of the concrete base forming the space. Forms a hygroscopic layer that absorbs moisture when the humidity is high and naturally releases it when the humidity is low, and the heat insulating layer.
For 100 parts by weight of cement, 3 to 50 parts by weight of synthetic resin emulsion as solid content and 1 part by weight of organic microballoon.
A heat insulating material made of a mixture of ~20 parts by weight, 0.3 to 5 parts by weight of carbon fiber, and 10 to 200 parts by weight of inorganic microballoons is formed by wet construction on the space side surface of the concrete base. That's what happens.

The structure for preventing dew condensation forming a space according to claim 2 includes forming a heat insulating layer on a surface of a concrete base forming the space on the space side, and forming a heat insulating layer on a surface of the heat insulating layer on the space side. Forms a hygroscopic layer that absorbs moisture when the humidity is high and naturally releases it when the humidity is low, and the heat insulating layer.
For 100 parts by weight of cement, 3 to 50 parts by weight of synthetic resin emulsion as solid content and 1 part by weight of organic microballoon.
It is formed by wet-applying a heat insulating material containing a mixture of ~20 parts by weight and 0.3 to 5 parts by weight of carbon fiber on the surface of the concrete base on the space side.

Here, the solid content of the synthetic resin emulsion is set at 3 to 50 parts by weight based on 100 parts by weight of cement, because if it is less than 3 parts by weight, the adhesion performance will decrease, and if it is more than 50 parts by weight, the fire resistance will decrease. This is because the cost will be high.

In addition, the reason why organic microballoons should be 1 to 20 parts by weight per 100 parts by weight of cement is that if it is less than 1 part by weight, the insulation performance will decrease, and if it is more than 20 parts by weight, the fire resistance and strength will decrease, but the cost will increase. Because it will be.

Furthermore, 0.3 parts of carbon fiber per 100 parts by weight of cement.
The reason why the amount is set at ~5 parts by weight is that below 0.3 parts by weight, the reinforcing effect of the matrix and the effect of preventing cracks due to shrinkage will be lowered, while above 5 parts by weight, workability will deteriorate and costs will increase. This is because the reinforcing effect is not improved that much.

In addition, in the structure for preventing dew condensation forming a space according to claim 1, the inorganic microballoons are used in an amount of 10 to 200 parts by weight for 100 parts by weight of cement, because if the amount is less than 10 parts by weight, other materials are expensive. This is because the higher the proportion, the higher the cost and the less it contributes to improving the fire resistance performance.If it is more than 200 parts by weight, the strength becomes brittle. Improving fire resistance performance 2 Considering strength, cost, etc.
The amount of inorganic microballoons is preferably 10 to 100 parts by weight.

Here, wet construction of a heat insulating material refers to forming a heat insulating layer by attaching a heat insulating material, which is a viscous fluid, to the surface of a concrete base by spraying, troweling, or the like.

[Function] In the dew condensation prevention structure forming a space according to claim 1,
Since the moisture absorbing and releasing layer is formed facing into the space, moisture is absorbed when the humidity in the space is high, and moisture is naturally released when the humidity is low, so that the humidity in the space is automatically adjusted.

In addition, for example, a paste-like mixture prepared by mixing and kneading a synthetic resin emulsion, carbon fiber, organic microballoons, and, if necessary, a water-soluble resin, a thickener, an antifoaming agent, an anti-mold agent, etc., is applied to the concrete base. The insulation material manufactured by mixing and kneading cement and inorganic microballoons was wet applied to form a seamless insulation layer, which effectively prevented heat conduction inside and outside the dew condensation prevention structure. Flame retardancy is improved.

Furthermore, the insulation layer itself has a moderate water absorption rate even though its moisture permeability coefficient is small, so when the humidity is high indoors, the insulation layer absorbs moisture and stores it within the insulation layer, reducing the indoor humidity. When the temperature decreases, moisture is released from the heat insulating layer and the humidity regulating function of the hygroscopic layer is assisted.

In the dew condensation prevention structure forming a space according to claim 2,
Similar to the dew condensation prevention structure forming the space according to claim 1, the moisture absorption and desorption layer automatically adjusts the humidity in the space, and the humidity adjustment function of the moisture absorption and desorption layer is assisted by the heat insulating layer. Furthermore, due to the inherent function of the heat insulating layer, heat conduction inside and outside the dew condensation prevention structure is effectively prevented.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, details of the present invention will be described with reference to embodiments shown in the drawings.

FIG. 1 shows a first embodiment of the structure of the present invention.
In the figure, reference numeral 31 indicates a dew condensation prevention structure that forms a space 33.

This dew condensation prevention structure 31 is formed of a concrete base 35. A heat insulating layer 37 is formed on the surface of the 33 spaces of this concrete base 35, and this heat insulating layer 3
On the surface of the space 33 in No. 7, there is a hygroscopic layer 39 that absorbs moisture when the humidity in the space 33 is high and releases it naturally when the humidity is low.
is formed.

This moisture absorbing and releasing layer 39 has a moisture content of 200 to 300, for example.
It is formed by pasting wallpaper that can maintain g/rrf, and is constructed in combination with a material that has moisture absorption and release properties, such as a super absorbent polymer, to impart moisture absorption and release properties to the wallpaper.

The heat insulating layer 37 is a space 3 of the concrete base 35.
It is formed by attaching a heat insulating material, which is a viscous fluid, to the surfaces of the three cases.

This heat insulating material is composed of cement, synthetic resin emulsion, carbon fiber, organic microballoons, water, water-soluble resin, thickener, antifoaming agent, fungicide, and inorganic microballoons.

The cement used is early-strength Portland cement.

In addition, synthetic resin emulsions include, for example, acrylic,
They are vinyl acetate type 2 synthetic rubber type, vinylidene chloride type, vinyl chloride type, or a mixture thereof.

The carbon fiber has a fiber length of about 6 mm, for example.

In general, organic microballoons have a particle size of, for example,
The diameter is 10 to 100 μm, and the specific gravity is 0. 04 or below. The particle size of the inorganic microballoon is, for example, 5-
It is said to be 200 μm, and its specific gravity is said to be 0.3 to 0.7.

Further, the thickener is, for example, methylcellulose.

It is considered to be a water-soluble polymer compound such as polyvinyl alcohol or hydroxyethyl cellulose.

Such a heat insulating material includes 28 parts by weight of synthetic resin emulsion (solid content equivalent to 12°, 6 parts by weight), 2.6 parts by weight of carbon fiber, 8.0 parts by weight of organic microballoon, and 0 parts by weight of water-soluble resin.
．． It is produced by mixing and kneading 100 parts by weight of powder into 100 parts by weight of a semi-liquid mixture consisting of 8 parts by weight, 160 parts by weight of water, and small amounts of a thickener, an antifoaming agent, and a fungicide.

The powder was composed of 100 parts by weight of early strength Portland cement and 16 parts by weight of inorganic microballoons.

The heat insulating material manufactured in this way has the properties shown in the following table.

Below, the margin, that is, the thermal conductivity is 0. 06 (kcal/mhr'
C), raw specific gravity is 0.54. Air dry specific gravity is 0.31. Bending strength: 12.8 (kgf/c4), compressive strength: 14.
7 (kgf/cd).

Adhesion strength6. 2 (kgf/d), moisture permeability coefficient is 0.
315 (g/bohmmHg) + water absorption rate is 31.4 (
%).

In the dew condensation prevention structure forming the space configured as described above, a heat insulating material, which is a viscous fluid, is sprayed onto the surface of the 33 spaces of the concrete base 35.

For example, through wet construction such as troweling and filling into voids,
A heat insulating layer 37 with a thickness of 10 to 15 plates is formed, and this heat insulating layer 3
After drying 7 sufficiently, add moisture absorbing and desorbing layer 3 made of wallpaper.
9 is attached to the surface of the heat insulating layer 37.

Therefore, in the dew condensation prevention structure forming the space configured as described above, the moisture absorbing and releasing layer 39 is formed facing the inside of the space 33, so that when the humidity inside the space 33 is high, moisture is absorbed. When the humidity is low, moisture is naturally released and the space 3
The humidity within the space 33 is automatically adjusted, and the space 33 can be maintained in a comfortable state for humans.

Furthermore, the concrete base 35 is coated with, for example, a synthetic resin emulsion, carbon fiber, organic microballoons, and if necessary, a water-soluble resin or a thickener.

A seamless heat insulating layer 37 was formed by wet-applying a heat insulating material manufactured by mixing and kneading cement and inorganic microballoons into a paste-like mixture in which antifoaming agents, anti-mold agents, etc. were mixed and kneaded in advance. , can effectively prevent heat conduction inside and outside of the dew condensation prevention structure, and can improve flame retardancy, and has a heat insulation performance close to that of organic insulation materials, and is flame retardant. From the standpoint of performance, a heat insulating layer 37 with higher strength and a smoother surface than conventional ones is formed on the concrete base 35 using a heat insulating material that has the performance of conventional inorganic heat insulating materials, and this heat insulating layer 37 is used directly as the base. By forming a moisture absorbing and desorbing layer 39 that also serves as makeup on top of this layer, the humidity within the space 33 can be adjusted to a comfortable state, and dew condensation can be prevented due to both the heat insulating and moisture absorbing and desorbing functions. In other words, the heat insulating material of the heat insulating layer 37 has a thermal conductivity of 0°06 (
kcal/mhr"C), and the thermal conductivity of organic insulation material (0.02-0.03kcal/mhr"C)
Since it is not so large compared to the organic heat insulating material, it can have almost the same heat insulation performance as an organic heat insulating material.

This is because air pockets will be formed in the mortar since it contains organic microballoons and inorganic microballoons. In addition, since air pockets are formed in the mortar, the raw specific gravity is 0.5.
4. Air dry specific gravity is 0. 31, making it possible to form a very light heat insulating material.

Furthermore, since such a heat insulating material is an inorganic heat insulating material containing a large amount of inorganic material, flame retardance can be significantly improved compared to an organic heat insulating material.

In addition, the insulation material has a cement matrix, which is then filled with microballoons and a synthetic resin emulsion.

Combining carbon fibers strengthens the internal bond, which lowers the compressive strength of conventional rigid urethane foam (1,
4-2. 0kgf/cIIN) and compressive strength of polystyrene foam (2,5~3.Okgf/c1i1
), or the flexural and compressive strength of foam insulation mortar (
The compressive strength of the heat insulating material of the present invention is 14.3, (] ~ 5. O) cgf/cm). 1kgf/c4. The bending strength is 12.8 kgf/di, which is significantly higher than before.

Furthermore, since it contains a synthetic resin emulsion, the adhesion strength of the heat insulating material to the concrete base 35 is 6.
2 kgf/d, it is possible to promote the integration of the heat insulating material into the concrete base 35, and it is possible to reliably prevent the heat insulating material from peeling off. For this reason, the insulation material can be applied wet, and it can be applied to ceiling surfaces, beamed walls, etc., which was difficult to install using conventional methods such as spraying foamed urethane or dry installation using insulation boards. Insulating materials can also be easily installed in buildings with many protruding corners, intruding corners, etc., such as circular-shaped buildings.

In this way, it is possible to improve the insulation performance, flame retardance, strength, etc. of the insulation material. There is no need to attach a flame retardant material such as a board and use this as a base to form the moisture absorbing/releasing layer 39, and it is possible to form the moisture absorbing/releasing layer 39 directly on the heat insulating layer 37 as a base. It is possible to significantly reduce the construction process, secure a large effective area (space), and significantly reduce labor and costs.

And, along with the improvement in the heat insulation performance of the heat insulation layer 37,
The temperature difference between the indoor side surface of the dew condensation prevention structure 31 and the room can be minimized, and the dew condensation prevention structure 31
It is possible to reliably prevent condensation from forming on the side surfaces of the room.

Furthermore, the heat insulating layer 37 itself has a moisture permeability coefficient of 0.315 (g
/ rd htaraHg), while the water absorption rate is 3
It has a moderate water absorption performance of 1.4 (%), and although its moisture permeability coefficient is small, it has a moderate water absorption rate.
Moisture that exceeds the amount of moisture that can be absorbed by the hygroscopic layer 39,
Moisture is absorbed by the heat insulating layer 37 and stored in the heat insulating layer 37, and when the humidity in the room becomes low, the moisture is released from the heat insulating layer 1! The moisture in the space 3 is higher than that which can be absorbed by the moisture releasing layer 39.
3, the heat insulating layer 37 can absorb moisture and reliably prevent the occurrence of dew condensation.

The right side of the above table shows the properties of the heat insulating material in the second embodiment of the dew condensation prevention structure forming the space of the present invention. The heat insulating materials in the heat insulating layer 37 of this example include 62 parts by weight of synthetic resin emulsion (solid content concentration 45%) (27.9 parts by weight in terms of solid content), 2.6 parts by weight of carbon fiber, and 10.4 parts by weight of organic microballoon. parts by weight, 125 parts by weight of water,
It is produced by mixing and kneading 100 parts by weight of early-strength Portland cement with 100 parts by weight of a semi-liquid mixture consisting of a small amount of a thickener, an antifoaming agent, and a fungicide.

The thermal conductivity of this insulation material is 0.05 (kca1/
mhr 'C), raw specific gravity is 0.52. Air dry specific gravity is 04
30, bending strength 14. 1 (kgf/cJ), compressive strength 16.5 (kgf/cj), adhesive strength 6. 8
(kgf/cffl), moisture permeability coefficient is 0, 127
(g/rrfhn+mHg), water absorption rate is 20.5
(%)Met.

By forming the heat insulating layer 37 made of such a heat insulating material on the concrete base 35, substantially the same effects as in the above embodiment can be obtained.

That is, the thermal conductivity of the heat insulating layer 37 is 0.05 (kca
l/1 mhr'C), and the thermal conductivity of organic heat insulating material (0.02~0,03 kcal/mhr'C).
), it is not so large, so it can have almost the same insulation performance as organic insulation materials.

Further, the heat insulating layer 37 itself has a moisture permeability coefficient of 0.127 (g/
While the water absorption rate is small (mhmmHg), the water absorption rate is 20.5 (%).
The moisture absorbing and releasing layer 39
Moisture that exceeds the amount of moisture that can be absorbed by the heat insulating layer 37 is absorbed by the heat insulating layer 37 and stored in the heat insulating layer 37. When the indoor humidity becomes low, the moisture is released from the heat insulating layer 37, and the moisture absorption layer 39
The moisture absorbing and desorbing layer 39 can assist in the humidity adjustment function of
Even if more moisture than can be absorbed occurs in the space 33, the heat insulating layer 37 can absorb the moisture.

Therefore, the dew condensation prevention structure that forms such a space has a thermal insulation performance that is close to that of organic insulation materials.
7. From the viewpoint of flame retardancy, a heat insulating layer 37 with higher strength and smoother surface than conventional ones is formed on the concrete surface using a heat insulating material that has the performance of conventional inorganic heat insulating materials. By using 37 directly as a base and forming a moisture absorbing and desorbing layer 39 on top of it, the humidity in the space 33 can be adjusted to a comfortable state, and the moisture absorbing and desorbing function of the space 33 can be adjusted to a comfortable state. Both effects can reliably prevent the occurrence of dew condensation.

Incidentally, between the heat insulating layer 37 and the moisture absorption/desorption layer 39, one coat of resin-containing mortar may be interposed between 1 and 2II [II+]. In this case, it is possible to apply fine-grained decorative materials, such as painting or fine-grained cloth, which require more precision on the base, and it is also possible to further increase the strength of the wall surface.

In addition, heat insulating materials are added to 100 parts by weight of cement, 3 to 50 parts by weight of synthetic resin emulsion in terms of solid content, 1 to 20 parts by weight of organic microballoons, 0.3 to 5 parts by weight of carbon fiber, and 710 to 710 parts of inorganic microballoons. Even if the amount of each material used is changed within the range of 200 parts by weight, substantially the same effect as in the above embodiment can be obtained. In this case, by changing the proportions of various materials, it is possible to change the strength, specific gravity insulation performance, fire resistance performance, moisture absorption and release properties, etc. A heat insulating material with moisture releasing properties etc. can be obtained.

Furthermore, in the above embodiments, an example was explained in which a small amount of a thickener, an antifoaming agent, and a fungicide were mixed into the heat insulating material, but the present invention is not limited to the above embodiments; antifoaming agent,
Even if a fungicide or the like is not mixed (or, if necessary, other materials are mixed, substantially the same effect as in the above embodiment can be obtained).

〔Effect of the invention〕

In the dew condensation prevention structure forming a space according to claim 1,
A heat insulating layer is formed on the space-side surface of the concrete base that forms the space, and a hygroscopic layer is placed on the space-side surface of this heat-insulating layer that absorbs moisture when the humidity in the space is high and releases it naturally when it is low. In addition to forming a heat insulating layer, cement 100
Based on weight part, solid content of synthetic resin emulsion is 3~
50 parts by weight and 1 to 20 parts by weight of two organic microballoons.

0.3 to 5 parts by weight of carbon fiber and 1 inorganic microballoon
The insulation material mixed with 0 to 200 parts by weight was formed by wet construction on the space side of the concrete base, so it has a heat insulation performance close to that of organic insulation materials, and is flame retardant. From this perspective, a heat insulating layer with higher strength and a smoother surface than before is formed on the concrete surface using a heat insulating material that has the performance of conventional inorganic heat insulating materials. By forming a moisture absorbing and desorbing layer that also serves as makeup, the humidity in the space can be adjusted to a comfortable state, and the formation of condensation can be reliably prevented through both the heat insulating and moisture absorbing and desorbing functions. I can do it.

In the dew condensation prevention structure forming a space according to claim 2,
A heat insulating layer is formed on the space-side surface of the concrete base that forms the space, and a hygroscopic layer is placed on the space-side surface of this heat-insulating layer that absorbs moisture when the humidity in the space is high and releases it naturally when it is low. In addition to forming a heat insulating layer, cement 100
Based on weight part, solid content of synthetic resin emulsion is 3~
50 parts by weight, and 21 to 20 parts by weight of organic microballs.

The heat insulating material mixed with 0.3 to 5 parts by weight of carbon fiber was formed by wet construction on the space side of the concrete base, so its heat insulating performance is close to that of organic heat insulating materials. From the perspective of flame retardancy, a heat insulating material with the performance of conventional inorganic heat insulating materials is used to form a heat insulating layer on the concrete surface that is stronger and has a smoother surface than before, and this heat insulating layer is directly applied to the base. By forming a moisture absorbing and desorbing layer that also serves as a makeup layer on top of this layer, the humidity in the space can be adjusted to a comfortable state. This can be reliably prevented.

It is a longitudinal cross-sectional view showing the body.

[Explanation of symbols of main parts]

31... Structure for preventing condensation 33...space 35...Concrete base 37...Insulating layer 39... Moisture absorbing and releasing layer.

Claims (2)

[Claims] (1) A heat insulating layer is formed on the surface of the concrete base that forms the space on the space side, and the surface of this heat insulating layer on the space side absorbs moisture when the humidity in the space is high, and absorbs moisture when it is low. In addition to forming a moisture absorbing and desorbing layer that releases moisture, the heat insulating layer is formed by adding 3 to 50 parts by weight of synthetic resin emulsion (calculated as a solid content), 1 to 20 parts by weight of organic microballoons, and 0 parts by weight of carbon fiber to 100 parts by weight of cement. .3 to 5 parts by weight of inorganic microballoons and 10 to 200 parts by weight of inorganic microballoons are wet applied to the surface of the concrete base on the space side. A structure to prevent condensation from forming. (2) A heat insulating layer is formed on the surface of the concrete base that forms the space on the space side, and the surface of this heat insulating layer on the space side absorbs moisture when the humidity in the space is high and acts naturally when it is low. In addition to forming a moisture absorbing and desorbing layer that releases moisture, the heat insulating layer is formed by adding 3 to 50 parts by weight of synthetic resin emulsion (calculated as a solid content), 1 to 20 parts by weight of organic microballoons, and 0 parts by weight of carbon fiber to 100 parts by weight of cement. A dew condensation prevention structure for forming a space, characterized in that the structure is formed by wet-casting a heat insulating material mixed with 3 to 5 parts by weight on the surface of the concrete base on the space side.