7 mistakes in installing windows that we make most often. Find out how to avoid them

Windows with the best settings do not completely fulfill their task if they are installed incorrectly. Improper assembly can lead to leakage and damage. How to make sure that the assembly team fulfills its task correctly? In this article, we explain what the steps for installing windows are, we suggest what to remember when doing it, and most importantly, we check which mistakes are most often made by assemblers. Find out what to take into account to make sure that your windows are installed correctly!

The installation of windows is as important as their choice!

Thinking about replacing windows or installing them in a new house, most often we mainly focus on issues such as the appropriate shape and the materials from which the frames are made. Properly selected windows often determine the style of the facade of the building, also affect the appearance and lighting of the rooms. No wonder the aesthetics of the windows makes an important aspect for buyers. In addition, a lot of attention should also be devoted to the selection of the appropriate window parameters, from the point of view of thermal and acoustic insulation, safety and light transmission. Although these two things – the appearance of the windows and their properties – are taken into account by almost everyone, many people trust professionals when it comes to assembly. The assembly of windows is a serious thing, so you have to entrust a team, but also it is good to know how to do the assembly. Just to make sure that the team will not make any mistakes, the consequences of which will negatively affect our comfort. Remember that even the best energy-efficient windows will have leaks if they are mounted carelessly. In the following paragraphs, we describe the errors that can be encountered most often during the various stages of window installation.

Error 1: Wrong planning of the window installation

The assembly of the window is as important as the planning. It is necessary to choose the right time for the installation of window and door joinery. Especially in the case of wooden windows, it is better to do this after finishing the work, such as pouring floors and laying plasters inside the building. In addition, if external wall insulation is planned, it is preferable that the windows are recessed first. Already at the design stage, we should also answer the question about whether we are interested in installing outdoor blinds. Some of them – such as the superimposed blinds (monobloc)- require that the window opening be enlarged to the size of the box (and the bay depends on the size of a roller shutter).

Errerur 2: The poorly prepared berry

Poor preparation of window openings is a mistake relatively often – and easy to see soon enough if you know what to look for. Let us remember that the window openings must be properly prepared not only to fit the window there, but also to take appropriate measures. The treatment of the edges of the bay consists first of all in aligning the surfaces. They should be flat, without irregularities, crevices and cracks. Such imperfections can, during the assembly of the window, lead to difficulties in hermetically sealing the sealing sheet. Let’s pay attention to leveling the bottom edge – this is the window base, from where it is important that it is perfectly leveled. Finally, the walls must be measured from to check their flatness and verticality.

Error 3: The incorrectly measured bay

Another installation fault is the assembly of windows that are too small or too large compared to the bay. Usually this is a consequence of incorrect measurements. The measurement of the bay should be carried out after the alignment of the edges, but before the outer walls are plastered. If we measure the bay before leveling, we can see that there are changes in the dimensions when aligning the walls – and in this case, even a millimeter can make a difference. Measurements should be made very carefully, using a measuring tape and a spirit level. The measurements must be made on both sides of the bay (external and internal), in addition, we must also make sure that the angles of the window opening are straight. In order for the window to be mounted correctly, it must be slightly smaller than the bay. So, we need a small gap in case the windows are deformed due to temperature fluctuations.

If it turns out that there are errors in the measurements, installing the wrong size windows will almost certainly cause problems in the future. In a situation where the opening is too small, the frames can be damaged (related to deformations caused by temperature changes). As a result we have problems with opening and closing the window, especially in summer. We may also encounter problems with the tightness of the window. When the gap is too wide, the assemblers will probably try to solve this problem by using too much foam, which, unfortunately, can also damage the frame. Too small a window size prevents a good connection with the wall, which negatively affects its tightness. If, however, it turns out that the window is too small, we should consider the use of a special tape or aerated concrete blocks.

Error 4: Mounting the window in a dirty bay

Careless teams sometimes put a window on a dirty base – this is one of the biggest mistakes that can be made when mounting windows. It is also a mistake that is the easiest to avoid. Just before installing the window, the wall surface must be cleaned very carefully. If contamination such as dust or plaster fragments persist, the window will not be waterproof! The foam spread on a soiled substrate will not adhere to it well enough, which will lead to unsealing, and through the small gaps between the window and the wall, cold air will enter the house. In addition, such dirt absorbs all moisture. So, before the window assembly process begins, let’s check if everything is cleaned.

Error 5: Incorrect fastening of the window, i. e. installation without skirting boards or without connectors

If we have a careless or inexperienced assembler, he can put the window directly on the base of the bay – without the window sills. Do not believe the information that their use is not necessary: the absence of a slat prevents the correct installation of the window sill. In the future this lack can cause water leaks. Moisture not only gets into the room and begins to penetrate the wall, but it can also cause the joints to loosen – and the window no longer effectively protects against cold air blowing in. It is also a bad idea to assemble the window without the support blocks – the movements of the frame located on the wall or the insulation lead to deformations and cracks in the plaster. The window frame must be mounted using special dowels, fixing pads and screws. The use of specific tools depends mainly on the materials from which the walls are made. For example, in the case of wooden houses or light concrete, standard screws to concrete are sufficient. Fixing pads – in case the space between wall and frame is too wide. In houses made of concrete, solid bricks and silicate or perforations, dowels and screws can be used. Dowels are also used in walls made of aerated concrete, stone or blocks created from ceramics. The attachment points should be arranged at appropriate distances – both too small and too many will be problematic. It is generally assumed that the correct distance between them is 70 centimeters in the case of PVC or aluminum windows or 80 centimeters when it comes to wooden windows. However, the correct distance between the attachment points should be indicated in the manufacturer’s instructions – the windows can differ from each other, so it is better to follow the instructions. Currently, it is rare for professionals to try to mount the windows only with foam, without the presence of mechanical connectors, but if we hit a team that uses this technique – we cannot allow it. Otherwise, deformations of the frame, leaks and cracks in the plaster may occur (and moisture will penetrate into it). We must also pay attention to the fact that there are not too many connectors – When the window is installed using too many fixing pads or screws, the connection between the window and the wall will be too rigid. This creates a certain risk of deformation of the window due to temperature changes.

Error 6: Incorrect sealing of the window

The incorrect sealing of the window is probably the most common error that we can encounter when it comes to the installation of the window. Only a careful seal guarantees complete protection against moisture. The most important rule to keep in mind when sealing is: more sealed from the inside than from the outside. A seal subjected to a very good insulation will have three layers: internal (sealing strips that prevent the passage of air and steam), medium (foam, insulating both thermally and acoustically) and outside (impregnated or expansion strips). The assembly, which includes such a complete seal, is called “layered assembly” (sometimes it is also called “hot assembly”, although technically this is not correct). The use of foam only as a sealant is not a mistake – if we have not decided to order a layered assembly, it is with the help of foam that the windows will be sealed. Thanks to the foam, you can achieve a good effect, at least if the team does not turn out to be careless. As already mentioned, the foam can only be placed on the cleaned base. It is important to distribute the right amount of foam. The economical application of the foam leads to the creation of an unsealed space. The consequence of using too much foam can be the deformation of the window profile. The foam must also dry completely before being processed.

Error 7: Leaving the protective film

The error does not apply so much to the assembly as to our actions before or after it. Removing the film before or immediately after assembly is a mistake, as well as leaving the film on the product for a longer time. The protective film must remain on the windows during the assembly itself and while the construction and renovation works are carried out at home – such as the application of external plasters. Removing the film too early can cause scratches or dirt that are difficult to clean. However, if the film remains on the window for too long, removing it will become difficult, if not impossible, due to weather conditions. Therefore, it is better to get rid of this protection within a month (maximum two) of assembly.

What to remember when installing windows. In the case of installing windows, we must first not forget two things. First of all, diligence is more important than quick work. Secondly, the way in which the assembly will proceed varies depending on many factors. The type of wall is important, (the material from which it is made, whether it is single-layer, double-layer or internally insulated), mounting location of the window (in the roof or in the wall), and above all: the window itself. Let’s remember that each one is different – it is mandatory to familiarize yourself with the manufacturer’s instructions before the specialists get down to business.

If you notice any defects in the installation of the windows, do not be afraid to communicate it to the team. Some errors can be corrected if they are recorded early enough. In turn, if we do not react – we expose ourselves to problems later or even the need to replace freshly installed windows.