Calculation of determining the dew point when insulating a house. Where is the dew point, and how to insulate the walls. Material for insulation work

Dew point determines the ratio of air temperature, air humidity and surface temperature at which water begins to condense on the surface.

Production and sale of materials, performance of work: Polymer floors Self-leveling floors

Dew point definition

Dew point determination is extremely an important factor when installing any polymer floors, coatings and self-leveling floors on any grounds: concrete, metal, wood, etc. The occurrence of a dew point and, accordingly, water condensate on the surface of the base at the time of laying the polymer floors of self-leveling floors and coatings can cause the appearance of a variety of defects: shagreen, swelling and shells; complete delamination of the coating from the base. Visual determination of the dew point - the appearance of moisture on the surface - is almost impossible, so the technology below is used to calculate the dew point.

Dew point table

The dew point table is very simple to use − hover your mouse over it... Dew Point table - download

For example: air temperature +16°С, relative air humidity 65%.
Find the cell at the intersection of +16°С air temperature and 65% humidity. It turned out + 9 ° С - this is the dew point.
This means that if the surface temperature is equal to or below +9°C, moisture will condense on the surface.

For the application of polymer coatings, the surface temperature must be at least 4°C above the dew point!

Dew point calculation

To calculate the dew point, you need devices: a thermometer, a hygrometer.

1. Measure the temperature at a height of 50-60 cm from the floor (or from the surface) and the relative humidity of the air.
2. Determine the dew point temperature from the table.
3. Measure the surface temperature. If you do not have a special non-contact thermometer, place a regular thermometer on the surface and cover it to insulate it from the air. Take readings after 10-15 minutes.
4. The surface temperature must be at least 4 (four) degrees above the dew point.
   Otherwise, it is IMPOSSIBLE to carry out work on the application of polymer floors and polymer coatings!

There are devices that immediately calculate the dew point in degrees C.
In this case, the thermometer, hygrometer and dew point table are not required - they are all combined in this device.

Various polymer coatings differently "relate" to moisture on the surface during application. Polyurethane materials are the most “sensitive” to the occurrence of the dew point: paint coatings, polyurethane self-leveling floors, varnishes, etc. This is due to the fact that water is a hardener for polyurethane, and with an excess of moisture, the polymerization reaction proceeds very quickly. As a result, a variety of coating defects appear. A particularly unpleasant defect is a decrease in adhesion, which cannot be immediately determined, and over time this leads to partial or complete delamination of the coating or polymer floor.

It is important to consider that the dew point is dangerous not only at the time of coating application, but also during its curing. This is especially dangerous for self-leveling floors, since the time of their initial curing is quite long (up to a day).

Epoxy self-leveling floors and coatings are "less sensitive" to moisture, but, nevertheless, the determination of the dew point is a guarantee of quality when installing any polymer floors and paintwork.

Dew point- this is the temperature of the environment at which the water in the air turns from a gas into a liquid (condenses).

Air humidity depends on its temperature. With the same amount of water vapor, cold air will be more humid than warm air.

If we smoothly cool the air, then a temperature will come at which the humidity will become one hundred percent. At this moment it falls liquid condensate(dew). This temperature is called the dew point.

The temperature and humidity of the air on the inner edge of the wall or roof of the house is much higher than on the street. This leads to the very smooth decrease in temperature inside the structure. With an illiterate selection of insulation, it is likely that inside the wall there will be such humidity and temperature at which condensation forms.

Dew point position in the design of the wall depends on:

• how warm it is inside the room;
• how cold it is outside;
• the width and thermal conductivity of the building materials that make up the wall;
• indoor humidity;
• outdoor air humidity.

Let's find out how the position of the dew point changes in different situations.

In a wall without insulation. If the wall of your house is not insulated at all, then the temperature inside its structure will gradually decrease from the inner edge to the outer.

And then the dew point may be located: in the middle of the wall; close to the outer edge of the wall; close to the inner edge of the wall.

In a wall with insulation outside. In a place where a heater of sufficient thickness is located, a sharp temperature drop will be observed. Then the dew point will be inside the insulation, and the entire wall will be warm.

If the insulation has too little thickness, then the dew point may shift to the middle of the wall or to its inner edge.

In a wall with insulation inside. In this case, it will also be observed sudden jump temperature in the place where the heater is located. In this case, the wall will be in the cold zone and the dew point will shift to the inner edge of the wall.

To find dew point temperature table must be used.

For this find in the table the corresponding room temperature and the dew point temperature will be found at the intersection with the current humidity reading.

What are dew point methods the article "Determination of the dew point: secrets and nuances" will tell.

Consequences of illiterate choice and calculation

The dew point that occurs inside the material leads to its moisture. Walls getting wet has the following consequences:

• Moistened concrete and bricks have less heat-shielding properties.
• On the wet wall mold and mildew may develop.
• In a room with wet walls there will be an unpleasant microclimate.
• If the moisture inside the wall freezes and crystallizes, then its crystals will destroy the material of the structure. Several cycles of freezing and thawing can lead to loss of strength of the material.
• For a heater, humidity is dangerous by the deterioration of its heat-shielding properties.

Advice! Wet insulation is easy to dry if you arrange special products. It is on this technology that a ventilated facade works.

The calculation of the insulation is reduced to the selection of its thickness in each case. In this calculation, it is necessary pay attention to the dew point position. An incorrect thickness of the layer of insulating material can lead to wetting and freezing of the entire wall structure.

To avoid getting wet load-bearing structure walls, it is best to place the insulation outside. In this case, it is necessary to provide for good ventilation of the insulation layer, as well as its protection from bad weather.

It is possible to place a heater indoors only at low humidity air or a small difference in temperature inside and outside your room.

Dew point - what is it and how to determine it in the wall, see the video:

About the dew point temperature, see the video tutorial:

The dew point is the relative temperature at which the accumulated water vapor begins to condense. A point with such a temperature is located in a certain place, in particular: on the wall outside, in the thickness of the wall, on the wall inside. Depending on the very location of the dew point, which may be further or closer along the very thickness of the wall to the inner area, the wall may be wet or dry. The dew point depends on the humidity and the temperature flow of the air inside the room. The lower the humidity inside the room, the lower the dew point is the temperature of the air inside the room itself. Absolutely everyone can correctly determine the dew point in the wall itself, and for this it is absolutely not necessary to possess and possess any special knowledge and skills, since it is quite possible to do it yourself.

What is dew point

One of the most significant problems in the process of designing and building a house is the protection of buildings from heat loss and, accordingly, the thermal insulation of important building envelopes. It is very important to know what the dew point is and how to correctly calculate this indicator. Definition exact value and finding the dew point, on which the Constructive decisions designing walls and coverings is an important issue when calculating thermal protection.

The dew point can move in the wall along its thickness in case of temperature changes outside and inside the room.

If the temperature inside the room remains stable, and outside it decreases, then the dew point indicator will move along the outer thickness of the wall closer to the room.

When making dew point calculations for a particular room, it is important to make a calculation for:

• The highest value of temperature and humidity indicators;
• Average value;
• The smallest value.

The temperature of the object on which condensation will form depends on two indicators, namely the ambient air temperature, as well as its humidity. For example, if the temperature inside the room is 20 o C and the humidity is 50%, then the dew point temperature will be approximately 13 o C. That is why, if there is an object with this temperature or less in the room, condensation will occur on it. If it is cold outside, then steam condensation will form inside the wall and moisture will be observed. If the dew point is not calculated correctly, then the constant formation of condensate will lead to its accumulation and gradually mold will begin to appear on the walls, which will lead to the destruction of the house.

The concept of dew point in construction

In construction, it is very important to correctly calculate the dew point, since if it turns out to be too high, then all building materials will last a very short time, as they will deteriorate very much under the influence of constant high humidity.

If condensation forms on the surface polymer materials, then this can lead to such defects as:

• surface swelling;
• Her large detachment;
• Shagreen.

Most likely, it will not work to visually calculate the dew point in the wall, for this you will need a table of special indicators and a non-contact thermometer.

Several factors can affect this indicator, in particular, such as:

• Wall thickness, as well as building materials used for insulation;
• Humidity;
• Temperature.

If the wall is not insulated, then the dew point will change under the influence of climatic conditions. If weather conditions are stable, then it will move closer to outer wall and the house itself in this case, does not suffer at all. With a sharp cold snap, this point will move to the inside of the wall. In this case, the room will be saturated with condensate, and the walls will slowly get wet.

Important! If climatic conditions are not taken into account during repair work, then if problems arise in the house, it will be quite difficult, almost impossible, to eliminate them.

If the wall is finished from the inside, then the dew point will be located between it and the insulation. With an increased level of humidity, it will move closer to the junction with the treated insulation, which can have a negative effect on the house. It is worth noting that in a humid climate, insulation can only be carried out if a high-quality heating system is capable of providing the same temperature indicators in all rooms. In the case of external wall insulation, the dew point will move inside the insulation layer. When purchasing a material intended for thermal insulation, you need to take into account this indicator and determine optimal thickness insulation.

Every person wants to live in a brick, panel or wooden house comfortable, however, it will not succeed in high humidity conditions. With condensation, the air becomes harmful not only to the house itself, but also to humans. If observed constantly high humidity, then the walls and ceiling may become moldy, especially in brick and frame building, which is very harmful to the body and is difficult to remove from the surface. Often you even have to dismantle everything finishing coatings to get rid of pathogens.

To prevent the formation of condensate, you need to calculate the dew point in the wall and determine how appropriate it is to carry out in the house repair work, insulation or even build a new house.

It is worth remembering that this concept is strictly individual for each case, which is why, it is necessary to take into account such factors as:

• Climatic subtleties of your region;
• Presence and frequency of wind power;
• wall thickness;
• Building material used for construction.

Humidity, although within allowable rate is contained in each insulation, which is why it is important to ensure that it does not rise and condensation does not form. You can carry out the calculations yourself, since there is even special program for kettles, which will help determine the level of humidity.

Knowing the location of the dew point, you can find what the thickness of the material used for insulation is. Thus, foam insulation can be carried out, preventing the formation of condensate in an undesirable place. However, it is imperative to know in what situation to carry out wall insulation from the inside, and when to carry out insulation - from the outside.

To calculate this indicator, it is necessary to take into account factors such as:

• climatic conditions;
• zone of residence;
• What is the border of the insulated wall;
• Operation of the ventilation system;
• Quality of work heating system.

In addition, this indicator depends on the material and thickness of the walls, the pressure in the heating boiler is measured, as well as the temperature outside and inside the room. This can be formulated in such a way that the warmer the region, better heating, ventilation system and the thicker the wall, the greater the statement of the internal insulation of the wall. As practice shows, it is most preferable to equip external insulation.

Definition: dew point

It is not enough to know what the dew point in the wall should be, you also need to determine how you can apply the results that this calculation gave. Knowing where this point is located, you can correctly determine the thickness of the object insulation, thereby preventing the formation of condensate.

There are certain factors that affect the dew point.

In particular, these factors include:

• climatic conditions;
• The presence of a heater;
• Permanent residence or temporary residence;
• Accurate level of indoor and outdoor humidity.

In some cases, it is simply impossible to carry out wall insulation. These parameters include the following: permanent residence in the house, if the wall thickness is sufficient, if ventilation system works in accordance with all standards, if heating system works good.

Can be brought quite specific example arrangement of the heating system. In particular, the better the ventilation and heating system, the greater the specific probability that internal insulation.

Features of the dew point in the wall

In order to ensure significant normal quality properties for all enclosing structures in terms of specific thermal protection, it is necessary to know not only the value of the conditional value of the condensate settling temperature, but also its position and passage within all enclosing structures. The concept of dew point in various structures for external walls, it is carried out in three main options and then a graph is built, where the location of the condensate contour can be different.

In particular, such as:

• The structure is made without additional insulation;
• Warming is only external;
• Insulation external and internal.

In a wooden house with a properly defined wall thickness, the dew point will be located near the outer surfaces, since the wood appears natural material and is characterized by the presence of unique qualities. It has a fairly low thermal conductivity and a high degree of vapor permeability. wooden walls do not require any additional insulation. A single structure can be competently erected with a layer good insulation only with outer side. If all the required calculations are carried out correctly, as well as the required thickness of materials is selected, condensate will not appear inside the room.

The design can be insulated from the outside and inside. However, in this case, in order to prevent the formation of condensate, it is necessary to provide an air passage, ventilation holes and equip an additional ventilation system.

Dew point formula

There are several various options dew point calculation.

In particular, such as:

• online calculator;
• table;
• formula.

It can be quite convenient to calculate the dew point according to the formula, which is carried out in the presence of known indicators of temperature and humidity level. The final value is considered approximate, due to the errors of some factors. For a residential area, normal humidity levels are 60%, and temperatures are 21 about C. Thus, it is possible to calculate the optimal thickness of insulation, which will help prevent heat loss from the room and freezing of the walls.(0 Votes)

Properly executed thermal insulation provides favorable living conditions and reduces maintenance costs. comfortable temperature. With the seeming simplicity of the process of insulation and the presence large selection thermal insulation materials, it is important to choose the right location for the insulation. This will prevent the formation of mold caused by the accumulation of moisture. That is why the dew point in construction is an important concept that characterizes the temperature of condensation. It is important to understand where it is in a particular case and how it is calculated.

What is dew point in construction

Many have heard, but not everyone can correctly answer what semantic load the widely used concept carries - the dew point. Its definition in construction is unambiguous. This is the temperature threshold at which moisture in the air condenses and turns into water droplets. The condensate formation area can be located both inside main wall as well as from the outside or inside of the building. The location of the condensate fallout zone is determined by a set of the following indicators:

• moisture concentration in the room;
• temperature conditions of the room.

At constant temperature and an increase in relative humidity, the temperature threshold for the formation of condensate increases accordingly. For a correct understanding of the processes, let's consider how the threshold for condensation increases at a room temperature of 20 ° C:

• at a humidity of 40%, moisture turns into drops of water at a surface temperature of plus 6 ° C and below;
• an increase in relative humidity up to 60% causes condensation at 12 °C;
• when the moisture concentration reaches 80%, moisture condenses at 16.5 °C;
• at 100% humidity, the condensation temperature corresponds to the internal one and is 20 °C.

The difference between dew point and temperature can indirectly estimate relative humidity:

• with a small difference - high humidity;
• with a significant discrepancy - the vapor concentration is negligible.

Depending on how far the dew point is from the room in the wall, the state of the surface changes - it can be wet or completely dry. This is due to the condensation of moisture that occurs when a cold surface comes into contact with warm air. Professional builders attach great importance to this parameter, since it is inextricably linked with the issues of thermal insulation of buildings and the creation of a comfortable microclimate.

Wall dew point - location options

The location of the dew point in the capital structures of the building is determined by the following factors:

• material used for manufacturing;
• the distance from the street surface of the wall to its plane, located in the room;
• outdoor and indoor air temperature;
• relative humidity outside the room;
• moisture concentration in the house.

Consider how likely the formation of condensate inside the room for different types walls:

• not thermally insulated;
• thermally insulated with outside;
• insulated from the side of the room.

For the non-insulated version, the following location options are possible:

• closer to the outer surface. At the same time, moisture condensation is impossible and the wall of the room is absolutely dry;
• with an offset from the middle of the wall into the room. There is no condensate, but it can occur when the outdoor air cools sharply;
• on the inside of the wall. With a sharp cold snap, moisture actively condenses.

With an external location of thermal insulation, the following options for locating the problem area are possible:

• in an array of thermal insulation material. This is the optimum position to guarantee a dry surface;
• in any of the three zones, similarly to the non-insulated version. The displacement is associated with incorrect calculations and the use of insulation of insufficient thickness.

Internal insulation significantly shifts the position of the condensation area towards the room and contributes to the cooling of the walls located under the heat insulator. This significantly increases the likelihood of moisture accumulation in any of these areas:

• inside the wall. The surface is dry, but can be moistened with significant temperature fluctuations with a shift towards the room;
• between wall and insulation. Condensation is inevitable during winter cooling;
• deep inside the heater. Droplets of moisture in winter are constantly collected, moistening the insulation. The result is dampness and mold formation.

The correct location of the insulation avoids the formation of dampness caused by an increased concentration of condensed moisture.

To determine the temperature threshold for the formation of condensate, various methods are used:

• settlement. Calculations are made according to a cumbersome formula that takes into account a number of coefficients, as well as the actual values ​​of climatic conditions. The calculation method involves determining the natural logarithm of relative humidity and performing a number of calculations. This makes it difficult to use it for the rapid determination of the threshold level of condensate formation;
• tabular. This method very convenient for practical conditions when it is important to quickly determine the condensation threshold. A ready-made table is used, in which, in small increments, the values ​​\u200b\u200bof room temperature and relative humidity are indicated. Knowing the value of these indicators, it is easy to determine the value of the required parameter from the table;
• using an online calculator. Using posted on specialized sites free program, it is easy to determine the required value. It is necessary to select in a simple and accessible shell of the calculator construction material, and specify its thickness. It remains to press the "calculate" button and the calculated value will appear on the screen.

Unfortunately, qualifications do not always allow you to independently perform calculations using special formulas. On the practical side, in order to quickly obtain reliable values, it is advisable to use a standard table. When using online calculators, only trusted sites should be used. The choice of calculation method for each specific case is determined individually.

Calculation of the dew point in the wall - example of the definition

Consider how to determine the dew point in the wall. To perform calculations, it is necessary to first determine the actual values ​​of the parameters using special devices:

• pyrometer, which is a non-contact type thermometer;
• hygrometer required to determine humidity:
• conventional household thermometer.

The sequence of operations for calculating the dew point for a particular room:

1. Use a tape measure to measure the level at a distance of 0.5-0.6 m from the floor.
2. Determine the air temperature and humidity at this mark using instruments.
3. Find in the table the required indicator corresponding to the measurement results.
4. Measure the degree of cooling on any surface with a pyrometer at the same level.
5. Compare the temperature readings and determine the difference in values.

With a difference exceeding 4 degrees Celsius, there is a high probability of condensation on the surface. This must be taken into account when performing construction works for warming.

For example, according to the results of measurements, the following data were obtained:

• air temperature - 22 degrees Celsius;
• relative humidity at a given level - 70%.

Then we perform the following steps:

• we determine, using the table, the temperature of condensate formation, equal to 16.3 degrees Celsius;
• we measure the temperature of the wall with a non-contact device, the value of which, for example, is 18 degrees Celsius;
• we calculate the temperature difference - 18-16.3 \u003d 2.3 degrees Celsius.

The indicated value is less than 4, which confirms the absence of condensation during measurements and indicates normal humidity. In this case, the dew point is located in the wall array not far from the inner surface. When cooling a non-insulated wall as a result of a sharp drop in temperature to a value of 16.3 degrees Celsius, the condensation zone will shift to inner surface.

Dew point for insulation from the inside - when internal insulation is allowed

In order to make a decision on the feasibility internal thermal insulation the following factors need to be analyzed:

• nature of residence in the premises (permanent or episodic);
• functioning of the supply and exhaust air exchange system;
• efficiency of the heating circuit;
• the degree of thermal insulation of all building structures (floor, roof, ceiling);
• the material used in the construction of the walls and their thickness;
• temperature conditions and humidity from the outside and inside the building;
• features of the climatic zone;
• presence from the outside of the street or neighboring premises.

As a result of a carefully performed analysis, it can be concluded that internal thermal insulation is possible under the following conditions:

• permanent residence;
• normal operation of ventilation;
• absence of internal temperature differences;
• stable operation of heating;
• insulation of building structures;
• increased wall thickness;
• living in a region with a relatively warm climate.

In each specific situation the decision is made individually. At the same time, there remains the likelihood of problem situations with poor-quality internal insulation. Instruct professionals to perform calculations, making internal wall insulation. The dew point of the walls, with an unskilled approach, can reach their inner surface and manifest itself negatively. Decision-making and execution of work should be entrusted to specialists. This will prevent annoying mistakes.

Dew point in the building - what is fraught with improper thermal insulation from the inside

The price of an error is quite high if thermal calculations are incorrectly performed, as well as violation of the requirements for the choice of thermal insulation materials. Especially if they are installed with inside premises. Regardless of the intensity of the heating system, more warm air upon contact with a cold surface, it inevitably cools. In this case, moisture concentration occurs and a number of serious problems arise:

• moistening the surface of the walls;
• destruction of heat-insulating material by moisture;
• the appearance of unpleasant odors;
• the presence of constant dampness;
• development of fungal colonies;
• abundant mold formation;
• peeling of facing materials;
• rotting wood;
• development of microorganisms;
• an increase in the incidence rate.

Condensation formation on the cooled surface of window panes is a prime example manifestations of the dew point and indicates the presence of deviations in the internal microclimate. To minimize the chance of condensation:

• maintaining a comfortable humidity level of 40-50% and a temperature of 19-22 degrees Celsius;
• ensuring normal air circulation. In residential premises, the volume of air exchange should be more than 3 cubic meters hourly on square meter area, and kitchen - up to 9 cubes.

You should responsibly approach the choice of thermal insulation materials and correctly determine the place for their installation.

Summing up

It is not difficult to independently calculate the temperature threshold of condensate formation. It is important to understand the seriousness of the consequences of improper placement of thermal insulation materials and the use of heaters of insufficient thickness. When performing calculations, take into account the climate and the whole complex of determining factors. Performance of heat engineering calculations must be carried out at the stage of building construction.

This is the determination of the temperature value at which condensation forms.

This value allows you to determine the localization condensation, which is located on the surface of the wall or inside it. The feasibility of its calculation is associated with determining the thickness of the wall to save heat.

The importance of determining the dew point is determined by the fact that this process affects whether the wall will be wet on the outside or inside. The condensation temperature depends on following factors indoors:

• humidity level;
• air temperature.

For example, at an air temperature of +20 o C and a humidity of 60% in a room, the temperature value of condensation on any surface is below +12 o C. If the temperature has dropped outside, and inside it is stably constant, then dew point will move in the thickness of the wall closer to the room.

The more precisely the value of the indicator is determined, the higher the probability of creating comfortable microclimate in buildings and structures. The dew point calculation allows you to calculate the segments of the highest humidity.

It is advisable to prevent these processes in order to avoid the development of decay processes and the appearance fungus and mold.

This is achieved dew point shift closer to the outer surface, that is, measures for warming the outside.

Competent calculation the thickness of the insulation will prevent freezing of the walls as a result of freezing and thawing of condensate. Optimally, if the condensate will fall inside the insulation layer.

The main indicators needed for the calculation are humidity and indoor temperature. They are used to determine household psychrometer.

This device determines both indicators. His work based on a thermometer combination cooled by a humidifier. The higher the humidity percentage, the higher the thermometer readings.

For construction needs, electronic devices have been developed that instantly calculate the values ​​​​of temperature and humidity and display them on the display. Also, some models have the function of calculating the dew point. thermal imagers.

There are several dew point calculation methods:

• according to the formula;
• according to the table;
• using an online calculator.

Formula calculation

Dew point calculation T using a formula, it is carried out at known indicators of humidity and temperature. The final value will be considered approximate due to the neglect of some factors.

t is room temperature o C, φ is humidity%, and 17.27 and 237.7 are constant values.

For example, for a room, normal values ​​are 60% humidity and room temperature 21 o C, calculation will look like in the following way:

So the dew point calculation looks like this:

The condensation temperature is 12.92 o C. Thus, the insulation of the walls from the outside prevent losses heat from the room and freezing of the wall.

Table calculation

The dew point can be determined using a table created by experts. In order to determine the dew point, for example, for 21 o C at 60% humidity, we are looking for line crossing temperature with a column of humidity and we get a value of 12.9 o C.
Table 1. Dew point definitions.

Calculation with an online calculator

How to work with an online calculator to calculate the dew point in a wall, look at the video:

Regulations

The need to calculate the dew point is regulated by building codes and regulations. SP 23-101-2004 "Design of thermal protection of buildings", as well as SNiP 23-02 "Thermal protection of buildings". Insufficient insulation shifts the dew point closer to the room.

Since the temperature in the area of ​​​​window blocks or doors is lower than the total calculated dew point, condensation in these segments is inevitable during the cold season. Dew point determination important for the implementation of the solution which side to carry out insulation work and what thickness it is more expedient to purchase a heater.

Important! The lower the thermal conductivity of the insulation, the thinner the insulation layer will be required. For example, the thickness of the insulation mineral wool 0.12 m will be enough when you need more than 5 meters of reinforced concrete to keep the heat in the room.

table 2. Dependence of wall material thickness on thermal conductivity

Minimizing heat loss and maintaining a comfortable microclimate are priorities in the design and insulation of buildings. Compliance with building rules and regulations, as well as sanitary and hygienic standards, will allow you to competently prepare engineering documentation and calculate the volumes of required building materials.