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  • Writer's pictureEuro Glazing

5 Common Window Installation Mistakes to Avoid: Tips from the Pros

Your windows must be installed properly for your house to be completely comfortable, energy-efficient, and secure.

Well-placed windows provide a tight barrier against the weather, keeping the cold air out in the winter and the hot air out in the summer.

This aids in keeping your house at a reasonable temperature while reducing energy costs.

Why Window Installation is Important

Yet, improper window installation may result in several detrimental issues. Air and water leaks are among the most prevalent problems related to subpar window installation. As a result of improper window installation, air and water may leak into your house via gaps and fractures that form around the frame's borders. This may result in drafts, water damage, and even mould formation.

Inadequate window installation service may lead to lower energy efficiency and air and water leakage. Air leakage via improperly sealed windows might make your heating and cooling system work harder than necessary. Along with raising your energy costs, this also overworks your HVAC system, increasing the frequency of failures and repairs.

Last, bad window installation might jeopardise your house's security. Windows may not be able to lock properly if they are not fitted properly, leaving your property open to attackers. This may seriously threaten your safety, particularly if you reside in a high-crime region.

Effective window installation is essential for your home's protection, comfort, and energy efficiency. You can prevent the issues brought on by improper Window Installation and take advantage of all the advantages that properly installed windows have to offer by making sure that your windows are put appropriately.

5 Common Window Installation Mistakes

The following paragraphs describe the most frequent errors at each window installation step.

1. Incorrect Planning of Window Installation

Planning well is just as crucial as the window installation procedure itself. You must choose the ideal time to install the joinery, including the windows and doors. It is advisable to accomplish this after interior construction work, such as screening and plastering, has been completed, especially with wooden windows. Therefore, it is preferable to install windows before exterior wall insulation if this is the intention.

If we want to install exterior roller blinds is a subject we should address during the design phase. Some roller blind kinds, such above roller blinds, need enlarging the window opening to accommodate the box's dimensions (which in turn depends on the size of the roller blind).

2. Failure to Prepare Window Openings Properly

It is common for window openings to be improperly prepared. Still, if you know what to look for, it is simple to identify early enough. Remember that window openings need to be properly prepared for the window to go in and the measurements.

The first step in window reveal treatment is levelling the surfaces. They need to be smooth without ridges, gaps, or fissures. Many of these flaws might make it harder for the sealing foil to adhere tightly during the appropriate window installation phase. We must pay close attention to levelling the bottom edge since this is the window's edge. Therefore it must be absolutely level. The walls should then have their flatness and verticality assessed.

3. Incorrectly Performed Measurements of the Reveal

Installing windows that are either too small or too big compared to the frame is another frequent error. This is often the result of inaccurate measurements. The reveal should already be measured when the base and margins have been levelled before the outside walls have been plastered. If you measure the reveals before the walls are aligned, it can be discovered that the dimensions have changed somewhat. In this situation, even a millimetre might make a difference. Measurements must be made carefully using a spirit level and tape measure. The inside and outside of the window frame should be measured, and you should ensure that the window opening's angles are straight.

The window must be slightly smaller than the reveal to be placed properly, leaving a tiny space if the window warps due to temperature changes. Remember that the kind of window you buy will also affect the proper width of the gap between the window frame and the frame, in addition to the frame's length. For instance, it will change based on whether the windows are constructed of wood, PVC, or aluminium. Typically, the distance should be less when using wood.

Installing a window that is the incorrect size will likely result in issues down the road if measuring mistakes are discovered. The frames could be harmed if the spacing is too tiny (due to deformation caused by temperature changes). This will make it difficult to open and close the window, particularly during the heat. Moreover, anticipate window tightness issues.

When the gap, on the other hand, is too big, the fitters will likely attempt to fix the issue by adding too much foam, which, regrettably, may also result in frame damage. A window that is too tiny won't be able to attach to the wall effectively, affecting how tightly it seals. Hence, if you later discover that the window is too small, you could use cellular concrete blocks or a customised border.

4. Installation of a Window on a Dirty Surface

One of the worst sins you can do while installing windows is when a worker is careless and places a window on a filthy substrate. The error is also the simplest to avoid. The base of the frame should be meticulously cleaned just before installing a window. The window won't be tight if there is filth on it, such as dust or pieces of plaster! A filthy surface will not allow the foam to stick to it enough, causing future breaches and allowing cold air to enter the home via tiny spaces between the window and the wall. That dirt will also take in any moisture. Hence, ensure the reveal's base has been cleaned before beginning the actual window installation procedure.

5. Incorrectly Sealed Windows

The most frequent error regarding window installation service is undoubtedly improper window sealing. Only meticulous sealing ensures complete moisture protection. The most crucial piece of sealing advice is to always seal more tightly on the inside than on the outside. A junction with truly effective insulation may have three layers: internal (sealing tapes that stop air and steam from leaking in), middle (foam that insulates both thermally and acoustically), and external (impregnated layer or expansion tapes). An assembly with such a thorough seal is simply referred to as a "layered assembly" (although it is technically incorrect to use the term "heated assembly" in these circumstances).

Foam by itself may hardly be regarded as a mistake when used as a sealant because, if layered installation is not ordered, it will be used to seal the windows. If the crew is careful, foam can help you achieve good results. The foam can only be positioned on a clean substrate, as was already explained. The proper amount must be distributed. You will have unsealed regions if you use the foam sparsely. The window profile may deform due to applying too much foam. Moreover, the foam must be completely dry before being treated.

Windows type vis Windows Installation Mistakes

Mistakes in UPVC Window Installation:

Improper Frame Alignment: One common mistake in UPVC window installation is to align the window with the wrong frame. This can lead to issues such as difficulty in opening and closing the window, air leaks, and compromised security. It's important to ensure the frame is level, plumb, and square before securing it.

Incorrect Sealing and Weather-stripping: Inadequate sealing and weather-stripping around UPVC windows can result in air and water leaks. This can reduce energy efficiency and lead to moisture damage. Properly applying high-quality sealant and weather-stripping materials is essential to achieve a tight seal.

Insufficient Fastening: The improper fastening of UPVC windows can lead to structural issues and poor performance. It's crucial to use the recommended fasteners and follow the manufacturer's guidelines to attach the window frame to the wall or open it securely.

Mistakes in Roof Window Installation:

Improper Flashing Installation: Flashing is critical in roof window installation to prevent water infiltration. One common mistake is improper installation or neglecting to install flashing altogether. This can lead to water leaks, roof damage, and potential interior issues. It's important to follow the manufacturer's instructions carefully and ensure proper flashing installation.

Neglecting Roof Pitch Considerations: Roof windows are designed for specific roof pitches, and installing them on roofs with incompatible pitches can result in water pooling, leaks, and poor performance. It's essential to choose roof windows that are suitable for the specific roof pitch and follow the recommended installation guidelines.

Mistakes in Double Glazed Window Installation:

Mishandling Glass Panes: Mishandling the glass panes is a common double glazed window installation mistake. It's important to handle the glass carefully, avoid excessive pressure or impact, and follow proper installation procedures to ensure the integrity of the glass.

Inadequate Insulation and Sealing: Double glazed windows rely on proper insulation and sealing to maximise their energy efficiency. Inadequate insulation around the window frame or gaps in the sealing can compromise the window's performance. It's crucial to use appropriate insulation materials and ensure a tight seal to prevent air and moisture infiltration.

By avoiding these specific installation mistakes and following the manufacturer's guidelines, homeowners and professionals can ensure that UPVC, roof, and double glazed windows are installed correctly, providing optimal functionality, energy efficiency, and durability.


After learning about the five common window installation mistakes to avoid, it's clear that proper installation is crucial for the longevity and efficiency of your windows. Installing windows may seem straightforward, but it requires skill and attention to detail to ensure a job well done.


Are upvc window installation a good choice for energy efficiency?

Yes, UPVC windows are known for their excellent energy efficiency. The material has low thermal conductivity, which helps minimise heat transfer. Additionally, UPVC windows can have features like double glazing and thermal insulation, further enhancing their energy-saving properties.

When is the right time to consider new window installation?

New window installation may be necessary for several situations. If your windows are old, damaged, or not functioning properly, it may be time for a replacement. Additionally, if you want to improve energy efficiency, enhance the aesthetic appeal of your home, or address specific issues like noise infiltration, a new window installation can be a beneficial investment.

What factors should I consider when choosing new windows?

When choosing new windows, consider energy efficiency, durability, maintenance requirements, style, and budget. Look for windows with high energy ratings, quality materials, and warranty coverage. It is also important to select windows that complement the architectural style of your home and meet your specific functional and design preferences.

Why should I hire professional window installation services?

Professional window installation services offer the expertise, experience, and specialised tools required for a successful installation. They can ensure that windows are installed correctly, providing proper insulation, weatherproofing, and security. Professional installers can also handle any challenges that may arise during the installation process, ensuring a smooth and efficient installation.

What should I expect during a window installation service?

During a window installation service, professionals will typically start by removing the existing windows and preparing the openings. They will install the new windows, ensuring proper alignment, insulation, and sealing. After installation, they will clean up the work area and conduct a final inspection to ensure the


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