Why do plastic windows sweat from the inside in an apartment?

Plastic is actively used for the manufacture of window systems. High-quality material has a long service life and beautiful appearance. However, during operation, some users encounter certain difficulties. The windows are starting to fog up. It is worth understanding what causes such a negative phenomenon and how it can be prevented.

Double-glazed window installation

To understand the reason for the appearance of condensation, let’s look at the design features of such blocks. They include:

The frame that is the basis of the system. To make the frame, a hollow plastic profile of suitable width is used. The geometric parameters of the window frame directly depend on the design of the double-glazed window. The base material is reinforced with aluminum to increase strength characteristics.
A double-glazed window consisting of one or more glasses connected to each other layer by layer while maintaining an air gap between the layers. The thermal insulation properties of an element directly depend on the number of layers. The choice is made taking into account the climate zone and the purpose of the room for which the plastic windows are intended. For residential premises, as a rule, 2-3-chamber structures are chosen. For northern regions, 4–5 chambers are preferable, as they allow better heat retention inside the house.

Fittings that ensure opening/closing of the sash during operation, if provided for by the design. This also includes handles and locks. Sometimes plastic windows are made blind, without the presence of sashes. The functioning of such structures does not require fittings.
Additional details, which include slopes, strips, window sills. Plastic is also used to make them. The characteristics and geometric parameters directly depend on the installation location and the size of the window opening.

Attention! Made from high-quality raw materials in compliance with regulatory requirements, the double-glazed window is completely sealed.

Ventilation valve

At the moment, the most effective element against condensation is a ventilation valve built into the window frame. Let's take a closer look at it.

Device Features

The air circulates through the ventilation valve.
It is a PVC box with a built-in movable feather. It regulates the flow of air masses. Usually they try to install it in a large window opening. Sometimes two valves are installed for efficient operation.

To install the valve, you do not have to spend a lot of time and effort. It is enough to take a screwdriver and a construction knife to get to work. The valve is installed on a balcony door or on a window sash that can be opened. It is better to choose an element with the help of a specialist who can advise on the size and characteristics. The valve is attached to the top panel.

Subtleties of work

The first thing to do is open the sash. The location of the valve installation is marked. This is necessary to determine the length of the rubberized seal. The old one is removed and the new one included in the kit is put in its place.

Cut out the seal

Need I say that all actions should be carried out extremely carefully? Cut out the seal and secure the plugs with holes for the screws. The installation location is determined where there is a cut of the seal. The plugs are needed so that the valve can be secured in the sash.

Valve for ventilation on a plastic window

Sash installation

There is a layer of double-sided tape on the bottom plane of the element. Remove the protective film and attach the housing to the upper end. Self-tapping screws are inserted into the eyes and screwed into the plugs.

Usually the manufacturer produces a kit containing two small sections of seal. They are needed for the valve grooves. It would be correct to place them between the screws that are screwed in.

The sash is ready, now you need to seal the frame. To do this, outline the length of the elastic that is necessary for the cutout. The area should be clearly opposite the valve.

All! The work is completed. Close the flap, move the valve regulator for the open-close function as desired.

Reasons for fogging of windows in apartments and private houses

In the off-season and winter, condensation begins to appear on plastic windows. The reason for such an undesirable process for every user can be found in the field of physics. There is inevitably some amount of water vapor in the air of every room. Once in close proximity to the glass surface at a point corresponding to the dew point, they begin to condense.

As a result, tiny droplets first appear on the surface. Gradually uniting, they turn into larger ones. As soon as their size reaches a critical size, the drops begin to flow down. Seeing this phenomenon, many people say that the window is “crying.” The process can take place both inside the apartment and outside. In some cases, condensation forms inside the glass unit. Let's consider each option separately in order to understand in detail the causes of negative processes.

Outside the glass unit

If ice appears on the outside of the window unit in winter, then we can safely talk about the appearance of condensation on the outside. According to a number of experts, this phenomenon clearly indicates that the dew point is located outside the house, and therefore the window effectively copes with the task, retaining heat inside the house. At the same time, in their opinion, the ice itself is not capable of harming the plastic frame and double-glazed windows, since water-resistant materials are used for their manufacture. In addition, due to low tides, water when the ice melts will end up on the ground.

This opinion can safely be called erroneous. Firstly, the very fact of the appearance of ice indicates that there is a heat leak, and therefore the window unit does not cope with the task of energy saving as effectively as we would like. Secondly, not only the plastic window, but also the material used to make the walls may face negative consequences. For example, a brick is initially designed for a certain number of freezing cycles. After exceeding the declared value, the brick begins to collapse. Rainy weather in winter speeds up the process. Condensation works in a similar way.

That is why it is important to determine the reason that causes the windows to fog up on the outside. It may lie in:

Poor insulation of the space between the installed frame and the wall. If the craftsmen did not fill in enough foam during the installation process or did it with tears;
Poor quality thermal insulation of slopes, which occurs when installing a narrow window in a wide opening;
Loss of tightness between the glass unit / sash or frame / sash;
Incorrect spatial orientation of the frame in the window opening. If the frame is shifted inside the apartment, then in this case the dew point also shifts. As a result, it ends up not inside the window system, but outside the house.

Attention! When performing design work, the dew point is inside the wall. Due to this, it is possible to prevent the appearance of condensation inside and outside.

Inside

The most unpleasant option that a user may encounter. Water inside the glass unit appears due to:

violations of production technology, which resulted in depressurization of the double-glazed window;
profile deformation during installation work;
cracking of glass, which sometimes occurs when transporting elements of a window system to the installation site or misalignment of the frame during installation.

Depressurization of a double-glazed window occurs at the production and installation stage. This is due to:

loss of geometry by the frame, which results in deformation of the glass unit;
poor fixation of sealant between glasses;
low quality sealing material;
violations of installation technology;
installation errors that led to distortion of the glass unit.

In warm weather, this problem is not noticeable. Condensation begins to form in the off-season. If such a problem occurs, you should contact the manufacturer.

From the inside

Condensation rarely forms inside or outside the window. Most often, windows begin to fog up from the inside. The reason for this lies in:

violation of installation technology;
changing the microclimate inside the house after installing a plastic window;
installing a single-chamber package.

The main mistakes made when performing installation work include:

incorrect measurement of the window opening before manufacturing the window block. As a result, the installed frame does not have sufficient contact with the wall;
poor adjustment of clamping force;
poor quality of technological gaps between the wall and frame;
lack of thermal insulation on slopes and window sills;
violation of technology when installing a window sill.

We invite you to watch a video that explains the reasons for the appearance of condensation on plastic windows:

Cause of condensation

Everyone encounters foggy windows from time to time. For example, when cooking actively boiling broth or compote. In this case, the appearance of drops is quite understandable and does not require adjustment. But if a similar phenomenon is observed constantly in winter, especially in the kitchen, then it is necessary to look for the source and eliminate the problem.

The appearance of drips is an alarming symptom, indicating that something is wrong with the microclimate. It is at least uncomfortable to be in such an environment. If the situation persists constantly, then it is not surprising that family members have decreased immunity, fatigue and respiratory diseases.

High humidity carries the risk of developing fungi and mold. They not only spoil the appearance of finishing materials, but also threaten the health of all residents.

If you think that condensation is formed due to poor quality products or installation errors, then you are mistaken. They account for up to 5% of all cases. Therefore, the reason should be looked for elsewhere.

It is possible to say with one hundred percent probability that the window itself is to blame for fogging in the apartment, only if droplets form from the inside between the frames. This means that the chambers have depressurized and it is impossible to correct the situation. Moisture accumulates inside such a structure, it often freezes, then thaws, and the materials deteriorate and become moldy. In this case, you will have to change the double-glazed window.

In other cases, the culprits of “crying” windows are:

high humidity - a lot of fumes from cooking food, wet laundry, indoor flowers, etc.;
poor ventilation - there is no exhaust hood, regular ventilation is not carried out and the ventilation duct is clogged. Wooden windows had “natural ventilation” due to the presence of cracks; metal-plastic structures did not have it. This reduces the penetration of noise from the street and prevents heat loss, but does not provide the necessary supply of fresh air. Nowadays, wooden structures are completely airtight, so they can also suffer from dampness;
insufficient heat - when the temperature in the room drops below the standard 19 degrees Celsius. Another wide window sill and heavy curtains can block the hot air from the radiator from reaching the top;
incorrect adjustment of the fittings - many people forget to switch the fittings to a different mode when the season changes. During cooling/warming, the profile narrows and expands, which leads to a violation of the tightness. If you do not adjust the fittings to the desired position, then the appearance of condensation is inevitable;
a worn-out seal also leads to a violation of integrity and, as a result, the appearance of drips.

Getting rid of condensation

To combat condensation, you can use special means. They are quite easily applied to the surface, forming a high-quality protective film. Manufacturers suggest using a spray, aerosol, or liquid. The release form does not affect the effectiveness, but only determines the ease of use. The composition of the special products is selected in such a way as to remove condensation without damaging the plastic from which the windows are made. There is no need to worry about the appearance of characteristic streaks and stains after treatment.

Attention! You should start processing glass only after the microclimate in the room has normalized. Otherwise, condensation will very soon appear on the windows again.

If it is not possible to purchase a special product, you should pay attention to folk remedies. These include:

Glycerin, which is applied to previously washed glass with soapy water and thoroughly dried. To prepare the solution, mix alcohol and glycerin in a ratio of 20 to 1. The alcohol will evaporate quickly enough, and the glycerin will form a thin protective film that protects well from the appearance of condensation;

Newspapers. When washing windows, many housewives carefully wipe the window with newspapers to give them a characteristic shine and get rid of the characteristic stains remaining on the surface of the glass. This method is also effective in combating condensation, since the printing ink applied to the surface of the paper has special properties that provide a water-repellent effect on the glass surface.

Soap. To combat condensation, the glass is first thoroughly washed. Then draw a mesh with a piece of soap and rub it thoroughly with a dry cloth, completely getting rid of traces. Similarly, you can protect a mirror from condensation in the bathroom.

Wooden windows sweat: what to do?

Condensation occurs frequently when a wooden frame is used rather than modern airless systems. Every owner of wooden frames wants to extend their service life, so fogging of glass is a problem. Due to the constant accumulation of moisture, the wood begins to swell, and mold and mildew form on its surface. In addition, humidity spoils the appearance of a wooden frame. Only the top layer is covered with varnish and paint. Water penetrates deeper, acting from the inside. Foggy windows cannot be ignored. It is worth understanding the problem by asking a simple question, why is this happening?

Pay attention to where the water collects. If it is on the glass indoors, it means the humidity level is increased. This effect is often observed in the kitchen, where food preparation occurs. Plastic windows also sweat where there is almost no ventilation, and in small crowded rooms.

The humidity in the kitchen is always high. Water is often boiled here, which releases steam that settles on the windows. In such a situation, it is enough to ventilate. If the inner glass fogs up on the outside and the outer glass on the inside, this indicates a broken seal. If a similar picture is observed on wooden windows, then we can talk about a manufacturing defect.

How can I prevent fogging in the future?

If condensation does form, it is worth considering some measures for the future to prevent fogging of plastic windows. Reducing the humidity level is mandatory. To do this you should:

Purchase a device that absorbs water vapor. It can be easily found in any specialty store. The cost of the device is relatively small, and therefore it is accessible to every family.

Regularly ventilate the entire apartment to reduce humidity levels. If the house is warm, the sash can be left to air for the whole day.
Remove flowers from the windowsill in the winter, as they are a source of excess moisture.
Turn on the hood while cooking dinner. Intensive formation of condensation is promoted by a simultaneous increase in the level of humidity and air temperature.
Dry clothes on the balcony or street. You should not use the interior space of the room or the battery for this.
Keep the ventilation shaft and battery open. In this case, it will be possible to ensure uniform heating of the air in the room and convective heat exchange.
Install a ventilation grill into the wide window sill, which will ensure the free passage of warm air.
Control the degree of heating of the heating batteries. If it is not possible to eliminate the problem through the efforts of utility workers, it is worthwhile to provide additional heat sources. A “warm floor” system or standard electrical heating appliances will cope with the task perfectly.

When installing, choose a higher-quality window design, the design of which was initially designed to prevent condensation from forming on the surface of the glass. So, for 4-5-chamber PVC windows, the thickness should be at least 7 cm. If the transverse dimensions are smaller, condensation will form more intensively.
Form a protective film on the glass surface that will not allow the smallest drops of water to settle on the glass. To clean the window, you should use napkins made of suitable materials. With a competent approach and a suitable combination, you will definitely be able to prevent fogging of plastic windows.
Treat the glass with an alcohol solution of glycerin. Acting as an antifreeze, such a composition prevents the formation of a protective film on the surface, preventing not only fogging, but also freezing of the glass.

How can we organize the flow of fresh air into the apartment?

Having understood the causes of fogging, having determined that the double-glazed windows are sweating due to the lack of constant ventilation of the apartment, the question arises of how to organize its supply.

The air that comes from the batteries, when mixed with what was in the room, loses the required level of humidity. To solve the problem, you need to “depressurize” the apartment by organizing the flow of air into it from outside. You should not be afraid that while solving the problem of why the windows sweat, you can freeze in the apartment.

Such an air influx will be minimal; it will not be able to cool the premises to a significant extent. The maximum that the indoor air temperature can drop is 2 degrees.

Important! When the indoor air temperature is at 20 degrees Celsius, you should not worry; if it is lower (about 15 degrees), you should take care of alternative heat sources.

You can organize the air flow like this:

through a window supply valve;
via a wall inlet valve.

An air conditioner is not suitable for this purpose; it only works with the air that is inside the room, without supplying it from outside.

Wall valves

Metal-plastic windows, which are covered with condensation from the inside, have high tightness, which is why a similar problem arises. If it fogs up, the problem should be solved by installing wall supply valves. They are not equipped with fans; they simply allow fresh air to enter from the street.

The advantages of such a system:

installation into the wall, without making changes to the design features of the windows;
Possibility of installation in a windowless room;
presence of thermal insulation from the wall;
retention of dust and insects using a filter or mesh;
possibility of installation both before and after renovation;
capacity up to 50 cubic meters meters per hour;
proper operation at low air temperatures.

The only disadvantages of such a device are the difficulties with installation work; a special device will be required for drilling holes with a diameter of 40 to 133 cm.

A wall inlet valve is a plastic pipe that pierces right through the wall. A grille equipped with a mesh is mounted on its street part. Inside, a block with a damper is attached to the pipe, which regulates the volume of air flow.

Models are equipped with automatic or manual regulators, the first reacts to changes in humidity inside the room, the second is controlled by the owner.

Briefly about window installation

The quality and service life of a window unit directly depends on compliance with production and installation technology. If the user cannot trace the first process, then the installation order can be controlled. This will avoid a lot of problems in the future.

Work begins with careful measurement of the geometric parameters of the window opening. The performance characteristics of the installed window unit directly depend on its quality. After this, you should contact the manufacturer to order a window unit.

Attention! Most often, companies involved in the installation of plastic windows take measurements themselves. It is better to entrust such responsible work to professionals.

The next step is to dismantle the old window unit, if any. You should act carefully to prevent mechanical damage to the window opening. The process is quite dirty and dusty. It is worth covering all pieces of furniture located indoors with construction film in advance.

Next, the window opening and the window itself are prepared for subsequent installation. Double-glazed windows are removed from the blind model. The doors are removed from the swing door. The protective film is removed from the outside, since if the apartment is located in an apartment building on the top floors, this will be quite difficult to do after installation. If necessary, elements for attaching a mosquito net are installed.

The installation ends with installation. At this stage, it is very important to ensure the correct spatial position of the mounted frame. As soon as it takes the desired position, the remaining elements are mounted and the functionality of the structure as a whole is checked. Particular attention is paid to thermal insulation work, since the likelihood of condensation on the glass surface largely depends on their quality. If everything is done correctly initially, there will be no difficulties during operation.

Thus, many people face the problem of window fogging. The reason lies both in natural processes and in the malfunction of ventilation equipment. A high concentration of water vapor in the air causes mold to form on the surface of the window unit, which negatively affects human health. By following the recommendations described above, you can create a comfortable microclimate in your home and significantly extend the service life of the window unit.

Why do plastic windows in an apartment sweat from the inside, what should I do?

In most cases, glass fogging occurs from the bottom up, and the volume of condensate released can be so large that the liquid formed on the glass also accumulates on the windowsill (flows down), forming entire water puddles. Which very often becomes the reason for contacting the installation organization with a demand to eliminate the problem presented on plastic windows. However, before making accusations, it is advisable to familiarize yourself with the reasons for the release of condensation on the windows, and based on the available information, make the best decision.

So, why do plastic windows sweat from the inside of an apartment and how to eliminate this defect? The answer is obvious, when certain climatic factors are created - they simply act as a condenser, on the plane of which the saturated air composition circulating in the room passes from a gaseous to a liquid state.

And the reason for this phenomenon is most often not the design features of the plastic window module, but the physical property of humid air to release moisture when it reaches the dew point, which is directly related to the ratio of climatic characteristics such as humidity, temperature, and atmospheric pressure.