How to properly cut the foam on the windows

What is the best way to cut the assembly foam

There is a cavity, such as sockets, filled with assembly foam. How to plaster them? What mixes stick to the assembly foam?

The foam is very often used for joint sealing when installing new plastic windows. In this case, the caulking procedure here is slightly different. The foam is also cut with a knife. Then the joint filled with foam is sealed with a wide hydro and steam. insulating tape, with an adhesive and sticky layer. This tape has a foil layer, so it also creates a heat-insulating screen. Now the entire joint, on both sides of the window is covered with primer from the sprayer, which contains antifungal composition that prevents mold. And now, when the primer has dried, you can safely apply plaster with a rubber trowel. Good manufacturers, these are Ceresit, Knauf Rothband and Vetonit.

In general, it is advisable to seal the foam in the joints. For this we apply two-component sealant with a rubber trowel. Prepare working mixture of sealant, mixing with drill (with nozzle) sealant and hardener, and apply to the foam joint with a rubber spatula. Therefore, for external seams and for seams in rooms with high humidity, this method is better suited.

How and what to plaster the assembly foam in 3 steps

In other cases, plaster, also using a rubber spatula of convenient width.

To plaster surfaces that are treated with assembly foam, you must first cut the protruding foam, then make small, enough and one millimeter, notches on the entire continuation of the joint.

Then we go to a construction store and buy ROTBAND gypsum plaster, produced by KNAUF

This plaster has proven very good just for plastering places that are treated with assembly foam.

You can putty plaster as in all other cases, there is nothing special.

Assembling foam is quite amenable to plastering, especially if you consider some nuances.

Before to begin to plaster the areas, filled with a foam, it is necessary to cut off the surplus of dry material, and slightly deepen the surface of the foam in relation to the sides. The surface of the cured foam try to even out.

Plaster the foam can be almost any composition (offer as an option Rotband, Forward KR, etc.), but it is worth for exterior works to use frost-proof.

The sequence of work is approximately the following:

  • dilute the dry mixture according to the instructions.
  • Apply with a trowel to the surface to be repaired (the foam area) with the transition to the base material of the wall and smooth it out. Note that thinly applied plaster on the foam will definitely crack when drying, so the layer must be at least 3 mm.
  • After the surface is completely dry, trowel the surface with a grid to get a smooth, even surface.

No problem, it can be plastered with anything, I do not understand your doubt. the foam is cut off flush with a knife, there under the upper smooth crust it is quite porous and any plaster will stick to it, even a simple cement mortar, but if you doubt and have a fear that in that place it will crack or break, then to help is the old tried and tested method. alabaster, deepen deeply clean up quickly mix and scrape/plaster quickly. Cure and harden very quickly, then you can simply use a spatula to remove the excess and rough edges and putty finish putty, you get cheap, sturdy and strong!

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Working with assembly foam is not difficult. It is only necessary to observe some rules:

  • It is advisable to carry out installation works during warm weather with air temperature from 5 to 30°С. In this case the polymerization process (hardening) is better. There are, however, and special winter foam, but they are a special conversation.
  • You need to study the upcoming object of work: the installation foam is best used when sealing the cracks with a width of 1 to 8 cm. If the size of the gap is larger, you need to fill it with a cheaper material (wood, brick, plastic, foam plastic). If the gap is less than 1 cm, you should use sealants, fillers and others.
  • Pre-treat the gap with water.

Causes and consequences: how to caulk the foam after installing plastic windows

Everyone knows that during the installation of any plastic construction, and now such technologies are used in the installation of wooden window frames, using a material such as polyurethane foam. It is quite convenient, sold in a special package from which, through the use of a special gun, through a narrow spout, is served on the surface where it is required. However, the question of how to seal the foam around the window, sometimes puts many in a baffling situation, as it tends to expand and go far beyond the limits that it is allotted. But in fact, it is not a problem at all, because even a child can cope with the task.

Wondering what to seal the foam on the outside of the window, and inside the structure, it is worth knowing that actually foam, it is also a sealant from the subgroup of polyurethane foam. But it also has a stabilizer, blowing agent, and other additives such as catalysts, which give it unique properties. The main indicators by which is evaluated foam for installation, are its viscosity, the primary, as well as the secondary expansion, viscosity, adhesion, that is adhesiveness to the surfaces, as well as the final volume of output.

It turns out that in order to understand what to seal the foam outside the window, you must first understand what is this very foam, and most importantly, what risks and threats may be dangerous for its functionality. And the foam can be in the form of a mixture with one component, but two-component compositions also have a place in the market. For better understanding it is also worth saying that the assembly foam can also be summer and winter, professional and consumer, and so on. Wondering what to close the foam on the plastic windows, you must first pay attention to what to do, but for what purpose, whether it means exclusively for decorative purposes, or it is necessary to produce for some other reasons.

  • It is clear that nothing has been invented by mankind perfectly, so the assembly foam needs to be protected from the effects of the environment. It does not tolerate very well the regular and constant exposure to moisture, and from the UV light, that is direct sunlight, it can even crumble into dust and ashes.
  • If you need to understand how to cover the installation foam on the windows, especially outside, it is worth thinking about how to avoid precipitation on it. Getting into the large pores of the frozen foam, the frost will inevitably freeze the water, and therefore expand, tearing your insulation. Therefore it is advisable to use waterproofing.
  • It is also important to protect the foam from moisture inside, which is especially dangerous in winter, in the form of condensation. That is a window inside the mandatory installation of a vapor barrier, the market is full of a variety of materials.

The appearance of the window, with mounting seams open to all winds, is also simply not aesthetically pleasing, the window will be untidy and unkempt, and the entire design in this case will go to hell, and this is yet another reason to search and understand what to seal the foam on the windows inside and outside.

How and how to scrape away the foam from a plastic window: from the beginning

True, you should start with a little different, because first you have to find out what to wash the foam from the plastic windows, because it is pretty strong holds, sticking to the glass itself, and even more tenaciously to the plastic profile of the window frame. It is clear that it will be optimal to remove the foam before it finally dries, but if the moment is missed, you should not get upset, because the real craftsman will always find a way out of a difficult situation.

  • The question of how to clean plastic windows from the assembly foam is easiest to answer before it hardens. The easiest way will be a trivial rag slightly dampened with a common solvent for paint, for example, acetone. Simply remove the foam with a squeegee, if possible, and wipe off the rest with a rag.
  • Another simple option on how to remove installation foam from plastic windows, is the use of special solutions that are designed to flush the installation guns. But you should act carefully because these compounds can damage the glossy surface of the profile of the window unit frame.
  • A wonderful tool called “Cosmophen” will do the job well, but it is not sold in small quantities. That is, it will have to spend quite a large sum for the substance, which you may no longer be useful.

There are also a variety of special purpose cleaners on the market, such as “Macroflex”, which do an excellent job. But here there are a variety of nuances, why these professionals and recommend to make sure that the agent will not damage the plastic. Simply wipe an inconspicuous area of the window frame with the solution, and wait a few minutes. If everything is in order, then you can proceed to cleaning, in other cases it is better to abandon the idea.

It will be somewhat more difficult to cope if the foam has already hardened considerably and has become hard. However, even in such circumstances there is no need to get upset, because there is always a solution. You can try to soften the material with the help of some solvents, and only then try to scrub. In addition, true masters use and generally simple ways, purely mechanically scrubbing foam, with a cut piece of plastic. It will not be able to damage the frame profile by its hardness, but the foam will peel off quite easily.

You can also just cut off the rest of the foam with a knife if possible, so as not to damage the surface, and then wipe with vegetable oil or the notorious drug for joint pain, called “Dimeksid”. Also, as an option, you can remove the foam from wooden surfaces with ordinary sandpaper, but then you will have a long and necessary to restore the coating, so it is worth a dozen times to think before you get to work.

Why does the foam need protection?

The foam is the best way to fill the space in the gap or hole, joint. If you do not think about protecting the foam, it will not last more than 5 years. In the process of such, improper use, the foam is constantly destroyed, as a consequence. the liquid, moisture penetrate into the gap and carry with them the destruction. And in the worst case, the crack inside the wall will become source of spreading mold and mildew.

A simple way of protection is to use an ordinary sealing tape. But if you protect the foam outdoors, the tape is unlikely to last long.

Another way. the use of special mixtures (primers), which give moisture protection. They have their own disadvantages. in most cases they do not protect against ultraviolet rays. the main problem of assembly foam, and invariably lead to its destruction.

Use other options. sealants, caulk, plastic, or acrylic paint. But if the excess foam is trimmed, they will not give sufficient protection.

A protective layer for foam prevents ultraviolet rays, creates vapor and water resistance.

So the best solution in such a case is putty or plaster. And its specific type and type is not important. This method is affordable and simple. even a person without any special knowledge or skills in the construction field can cope with such work.

The puttying process

Wait for the foam to expand and dry completely. In ready-to-work, it is wave-shaped, and often the excess foam appears in unusual points and positions. Hide with plaster such fragments will not work, so they are removed beforehand. For this purpose, the excess foam is trimmed with a small margin deep into the wall to use the putty.

Cut the foam mounting not earlier than 12 hours after application, but it is better to make sure of the drying time. They are specified on the spray can.

Before applying plaster, place regular painter’s tape around areas to be worked on to protect a clean, unmaintained surface from staining. Remove the tape after the plaster is completely applied and has dried.

Useful hints and recommendations from professionals

Once you have decided how to clean the foam from the hands, it is worth thinking about other nuances regarding cleaning. Builders give the following recommendations and tips:

  • It is definitely worth using hand cream at various stages of any cleaning process. It will greatly improve the skin’s condition.
  • It is undesirable to use vinegar to clean hands from assembly foam. The acid can do a lot of damage to the skin.
  • It is better to make a preliminary protection: rub the hands with cream, wear gloves, use a special device for applying the foam.

If you have a lot of free time, the thin film of residue of dried foam can be removed with tweezers. This is ideal if the areas are small and do not have severe skin damage.

Does the cut of the assembly foam need to be sealed??

The assembly foam is an excellent insulator, but it also needs insulation. If this is not done, the surface will begin to crack under the effects of solar radiation and moisture. Therefore, it is necessary to hide its cut, so that the foam does not collapse before time (usually its insulating properties last for 4 years). Polyurethane can be used as a sealant, as the most suitable for this kind of bonding. Pre-compressed sealing tape is also widely used to cover the foam. However, it should be understood that the construction adhesive tape is a very questionable solution in terms of design. In addition, no finishing materials can be applied on top of such tape, because once soaked in them, the tape will begin to peel off.

In search of options on how to get rid of the assembly foam on the hands, many find completely barbaric methods. It is worth thinking not only about the result of cleaning the skin, but also about preserving its integrity.

Do not use mechanical methods to remove foam from your hands. In particular, you can not use metal, stiff brushes, brushes made of metal, knives and other cutting objects. Such exposures can cause skin damage, deep wounds.

Another popular method is the use of acids and aggressive chemicals. But it is almost impossible to predict the behavior of chemicals. The result can be deep and extensive skin damage, poisoning, respiratory problems.

How does the heating of a plastic window work

Double-glazed windows with heating for most Russian buyers are quite incomprehensible design, it is worth a closer look at the features of this product. In fact, it is an ordinary double-glazed window, equipped with a special glass that has a heating system. Such an element combines two functions: heating air flows and letting natural light into the room.

Heating helps to get rid of ice, condensation, to equalize temperatures, getting rid of their differences. In addition, heat often escapes through the glass, and windows with heated glass will help get rid of this problem. The function will not only keep the heat in the room, which appears from the heaters: it can be an effective means of heating rooms, regardless of their area. The glass can be heated by electricity. To do this, the window construction must be electrically powered; it can be hidden in a special box or immured in the wall.

How the heated glass works in the window

Protection principle

If the master has decided to apply putty to cover the foam, then you need to adhere to a certain algorithm of actions. You can start any operations only when the foam is completely dry. This process usually takes 10 to 12 hours. If there are areas that protrude above the level of the glass, then they must be carefully cut away with a sharp knife.

During this procedure it is necessary to go a little bit deeper into the base. The surface must be cleaned of debris and covered with a layer of primer. When the applied agent dries, you can apply the putty solution, but not a thick layer. After the complete curing, again apply the prepared mortar.

properly, foam, windows


The surface must be grinded with emery paper, primed and painted. If the master is not planning to use putty, then the excess lengths of cut off flush with the PVC window. Remove all irregularities with sandpaper. In the final stage, all that remains is to paint the surface. For these purposes, it is desirable to use a compound based on acrylic.

Apply the product only in upward direction, gradually approaching the corners of the frame. If the surface is putty or paint, then the final life of the formed joint exactly will not be inferior to the operation of the building.

Important! To putty the foam, it is better to choose a frost-resistant material, which is freely available in modern construction shops. Many of them are a powder, in which necessarily add a certain amount of pure water to get a solution of the right consistency.

The putty is applied to the surface to be treated and carefully smoothed out. If the layer will be too thin, over time, it may be covered with numerous cracks. The thickness of the finishing material should be at least 3 mm. To make the seams aesthetically pleasing, it is better to use construction mesh.

Classic mesh to improve adhesion

Installing the window sill

If your particular sample is protected by a film from below, remove it, otherwise anything can happen. Direct installation we start with the groove in the window unit. Foam its lower shelf, barely pressing the trigger of the gun:

How much foam is needed

That way we provide guaranteed tightness of the connection. Next step, the foam is applied under the far edge of the future window sill in a wide, solid strip. It will have to effectively prop up the edge, thereby avoiding the appearance of a gap under the window. After that dense foam “snake” is already all the bottom “slope:


Before applying the foam, I recommend wetting the surface under the window unit and the window sill itself from below. This will significantly speed up its curing and adhesion. The height of the layer of foam should match the thickness of the wedges / self-tapping screws, you can apply a little more, but do not overdo it.After the application it will gain about 100% of its volume (by eye), and can easily tear the window sill, from which it will go hump. It is important not to get it dirty when you put it in the groove, be careful.

After you put the window sill on the wedges / self-tapping screws, you will need additional foam gap from the wall. Do this approximately flush with the wall surface. In an hour you will see that it will already be protruding.

The load on the sill

Once the foam is in place, you will need to put something heavy on the “patient”: a box of tiles, sacks of plaster, dumbbells While doing so, we’ll put the weight closer to the inner edge. the outer one will be resting against the window frame. Under the load it is extremely desirable to put something flat, like the same pravila, so that the weight is distributed evenly over the area and there were no holes or humps:

Let’s see what the level says

This is also often a sin installers. foam, put the bags. When we do everything with our own hands, we can periodically control the level and the plane during the first hour. you never know what can happen. In our case everything was normal:

If something is misaligned somewhere, or a hole is formed, it’s not too late to fix it. On the pits you will just need to remove the weight. If after a few minutes it will not break up the foam, you can put under this place another wedge or a piece of foam plastic, for example. In the case of a slight skew, it is simply enough to move the weight, or add/remove it from one side.

Now I will explain, if who has not guessed, for what we noted the axis. When we will do slopes, we, understandably, will try to maintain the same angle of their mortar. And when we make these very slopes, we have the “ears” sill will be set at the same distance from them. That’s the whole secret. Full symmetry. All neat, all beautiful.

In the end, the only thing left is to put plastic plugs on the ends of our hero, but this is best done at the very end of the repair, after the wallpaper.

After a couple of hours after the installation of the window sill with our own hands, we can cut the foam and seal the holes around it. Under it is most convenient to do it is not right (it will not fit), and the guide profile 27 × 28mm.

Landing pads, shims and straightening plates: Stiffening the structure

Here our primary task is to stand the window sill on the pads. At this stage we as if doing fitting before window sill foaming.

Depending on how high the window is installed, in relation to the window sill base, based on this we select the material to install the anchor points under the window sill.

The pads are needed for stiffening the window sill. The window sill is established on supports, and the foam already gives to a design durability and indissolubility.

I use a normal joist 40×40 or 50×50 in my work. in Leroy Merlin or other construction hypermarket.

Our task is to align the window sill as close as possible to the bottom window profile.

There are support profiles whose design already allows you to install the window sill so that the joint with the bottom window profile was very tight. But, in most cases, we will need to install support pads or stiffening plates at least four points near the base profile.

Here it depends on the situation. If several straightening plates are enough, then we make only with them. If it is not enough, then we saw off cubes from a bar of necessary height and make supports for a window sill from a bar.

In the same way we expose four supporting points on an edge of a window sill along a plane of a wall. It is very important to put the outermost supports as close as possible to the side wall.

Otherwise, the edges of the window sill will “walk” after caulking and the window sill will not be rigid in these places.

Why foam needs to be sealed?

If the installation foam is used indoors, it is not affected by external factors in the form of high and low temperatures, precipitation, wind, sunlight. All these problems are present in the street, so you can solve them by finishing the facade. If this is not done, the quality of the foam will deteriorate and the foam will not be able to perform the function it was designed for.

In addition, not closed decorative assembly foam spoils the aesthetic perception of the facade. Windows look unattractive, incomplete. In small cracks can penetrate cold air, which may cause a draft in the room. Closing installation joints can help solve these problems.

Read more about what kind of lining can be installed on plastic windows from the outside in our article “External lining for plastic windows: types and peculiarities of choice”

Exterior metal soffits are very practical. Read how to install them with your own hands at

How to properly seal windows and sills after the installation of plastic windows on our site.

Ways to close the foam

What to seal the foam around the window from the street, without spending a lot of money? How to do the work, how to keep the style of the building? All these questions are quite solvable, if you study the market of construction materials.

One of the most affordable and quickest ways to hide mounting seams is to install soffits. Plastic windows are well suited for plastic windows, less often used metal models. They allow you to hide the foam, make the seams airtight, increase the service life of the construction.

Some apartment owners use plaster. This option is the most affordable, but also time-consuming. If you use plaster, you will have to prepare the wall in a special way, use a material suitable for exterior work, before you can seal the foam after the installation of plastic windows.

In order to bring the joints in order, you will need to wait until the foam dries after installing the windows, cut off its excess as evenly as possible. If you plan to seal the joints with plaster, the foam should be cut deeper by 2-4 mm. On the outside of the sealant layer is worth doing more. It is desirable to level the surface of the frozen foam. After that, you will need a sealant. You do not need a lot of it, so you should not stir a large amount at once.

Once the sealant has dried, you can begin to apply putty. It is most convenient to do it with a trowel or a knife. The solution is better to apply a layer of not less than 3 mm, as thinner when drying with a high probability of giving cracks. In order to improve the protective effect, you can use water-based paints. They can not only protect the plaster, but also make the appearance of windows more attractive. The color of the paint does not matter, you should choose it according to your own taste.

Sealing the assembly foam with plaster

What to caulk the assembly foam. to create the perfect mortar

How to caulk the foam. a question that has recently arisen quite often. Various external factors lead to a deterioration of the assembly foam, which at some point can not cope with its direct purpose. Therefore, consider proven ways that allow you to plaster the foam without much time and effort, but guarantee quality and reliability, which is needed for modern metal windows.

How to Caulk the Assemblage Foam. Reliable protection Rehau window for a long time

Assembling foam as a result of exposure to moisture, light and other factors after a while loses its qualities. Including the foam will dry out, gradually gaining moisture. It is necessary and violation of the features of thermal insulation. Therefore, experts recommend that you think in advance about the slopes and caulking foam on the outside and under the window sill. Sills in the windows are of great importance, because they allow hiding the installation seams, contributing to the longevity of the construction as a whole. First of all, you should determine the optimal material for the lining.

The simplest option is dry mixes. A standard plaster can be used for the lining. But this option initially requires the preparation of the wall for the material. In the presence of large cracks requires the application of a layer of mortar on the wall, using a special mixture. Among the necessary tools are putty for exterior work, gloves, a small knife, trowel, water and a container for the mortar.

How to caulk the assembly foam. A proven set of actions

Cut off the excess dried foam on the outside of the joints. When using putty for sealing, it is recommended to cut the assembly foam deep into a few millimeters for a thicker layer of sealant on the outside. A flat surface of cured foam is recommended.

Next, wearing gloves, we prepare a solution of sealant for exterior work. For this we will not need a lot of mortar, so it will be better to knead less, then you can add more as needed. Instructions for preparing the mortar can be found on the material packaging.

The mass of putty is applied with a knife or trowel. choose according to personal preference and the place of sealing, level the surface. Cracks can appear after a very thin coat of putty dries. To avoid such trouble, it is better to apply a layer of mortar in a few millimeters. taking into account the appearance of the building.

In this way it is possible to protect the assembly foam from the sun’s rays, which can lead to the destructive effect. This also protects the foam from the effects of moisture, which when penetrated from the outside, leads to the destruction of the slopes and other elements of the connection. Also the aesthetics of the building is improved.

The best effect of the white slope is achieved with the use of water-emulsion mixture under the plaster. The work is performed using special tools. Slope from plaster mixes will be an excellent choice for the outside.

Plastic panel lining

To execute a plastic panel slope is much easier. From a large panel on the size of the slope should be cut pieces for the 3 sides of the window. A special plastic strip fastens the panel to the window.

Side panels are installed at an angle of 90-110 degrees relative to the window. Attaching each panel to the wall, filling the gap between the old slope and the window with installation foam. for better insulation. After the foam has dried, get rid of the dried residues. The gap between the panel and the wall is closed by tightly touching the F-shaped strip.

Gypsum plasterboard linings are made similar to plastic linings. The installation can be done in two ways. by mounting the prepared panels to the profile or sticking them on the glue. Thermal insulation is ensured thanks to the mineral wool insulation. After installation the plasterboards are treated with primer. Then the painting is done. To ensure a completely even corner, a painting steel corner is glued to the gypsum board corner with putty.

All this proves the possibility to use different methods of PVC window lining finishing. Today plastic windows are still the preferred option because they ensure excellent water and heat insulation properties, durability and reliability. The use of gypsum plasterboard slopes contributes to the preservation of heat and resistance to moisture. But the plastering of slopes as a finish is outdated, given the rather poor protective properties, which are not enough for modern PVC windows.

How to putty the assembly foam. professional help, confidence in every decision

Still, work with window and door structures requires some training and experience for reliability and quality results. Therefore, for many people it is preferable to turn to professionals who can guarantee the stated result at affordable prices. the company’s website always provides data on the services, detailed information can be clarified with the managers. Caulk the mounting seams and perform related work according to modern quality standards.