June 16, 2025, 10:00 am | Read time: 7 minutes

There are various reasons why windows are replaced. Most often, it happens during a renovation or remodeling. myHOMEBOOK explains what you should keep in mind.

Window Replacement – The Benefits

Noise Reduction

New windows with soundproof glazing can significantly reduce outside noise, which is a major advantage, especially if you live near streets or other noisy areas.

Energy Savings

Old windows perform poorly in terms of energy efficiency compared to new models. This is another reason to opt for new windows. With government funding that supports window replacement as part of an energy renovation project, you can apply for grants. However, these should be applied for before handing over contracts to construction companies.

Security

New windows can potentially offer more security. Windows with sturdy frame materials and secure glazing can enhance the safety of the house and possibly even prevent break-ins.

Windows Are Defective

If functionality is limited and windows no longer open or close properly, it might be time to choose new windows. Damaged windows can also pose a security risk.

Windows Require Maintenance

Old windows need to be painted and sealed more often. Replacing them means less maintenance and peace of mind for several years.

The Right Glazing

The appropriate glazing depends on several factors. To choose the right option, consider personal preferences and the house’s surroundings. Key factors include security, soundproofing, and energy efficiency.

• Sun Protection Glazing: Sun protection can play a crucial role in choosing glazing. Sun protection glazing reduces the amount of heat and UV rays that can penetrate through the windows. It can also minimize heat transfer, keeping indoor spaces significantly cooler.
• Insulating Glazing: Also known as thermal protection glazing, it can reduce heat loss and increase thermal insulation. It consists of at least two glass panes sealed with an air or gas-filled space between them.
• Opaque or Transparent: Floor-to-ceiling windows may be desired to be partially opaque, especially for bathroom or bedroom windows. Location is often crucial. Rooms on lower floors can sometimes be easily visible. For more privacy, frosted glass is recommended for the lower floor. It allows daylight in without darkening the room. Opaque glass can be equipped with energy-efficient features just like transparent glass.

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The Suitable Window Frame

Wood, plastic, or aluminum windows – the choice is yours when purchasing. Recently, plastic windows have become increasingly popular, likely due to their good price-performance ratio. With excellent thermal insulation using double or triple glazing, plastic also offers high soundproofing, is easy to maintain, and very durable. Online, you can get three plastic windows (123 cm x 148 cm) starting at 2,100 euros, including installation. Quantity matters here; the more windows needed, the cheaper the offer.

If you want to install larger windows, frames made of plastic with an aluminum cover are excellent. Like plastic windows, this frame impresses with its maximum lifespan and high stability. Both options offer a wider range of colors and better burglary protection.

Replacing Windows Yourself

If you want to replace windows on your own, you should definitely have enough experience. A lot can go wrong during installation. Here are some important points to consider:

• First, remove all windows. Lift the windows out of the hinges, and the frame should ideally be cut diagonally with a jigsaw. A crowbar can help if the frame is stuck.
• Sometimes the frame is screwed in. In this case, you need to remove the screws.
• Be careful when removing the windows. Avoid further damaging the wall openings.
• After cleaning with a hand broom, you can use a vacuum cleaner to assist.
• The masonry can be treated with an adhesive primer before installation, especially if the outside temperatures are colder.
• Important: Align the new window level and then seal it all around with a connection joint from the window to the wall.

Tips on Sealing and Insulation

• Proper window sealing is crucial. If you want to attach the supplied window seals like sealing tape or films, be sure to follow the manufacturer’s instructions. These are usually attached around the frame. Sealing tape ensures no moisture can penetrate. There are outer and inner sealing films, both of which must be professionally attached to the window frame before installation. The sealing tape should not have any wrinkles.
• Just like sealing, good insulation is important for the newly installed window, especially if you want to achieve optimal thermal insulation. Insulating tapes and special sealing tapes are essential when replacing windows. It’s best to consult a professional before installation to avoid mistakes later.
• The window should not be mounted in the exterior wall without a thermal bridge. It’s best to position the window according to the wall’s formwork. If you mount the window in a single-layer exterior wall, it’s advisable to attach the window in the middle third.
• A level and washers are useful tools for better handling. Precise alignment and installation of the frames are crucial for the windows’ functionality.
• Sometimes new windows come with support blocks. If you stick the blocks to the frame, you need to know the exact position. If the blocks are positioned incorrectly, they are not sufficiently load-bearing and can deform the windows.
• Now you can check the wall opening again. Then place the support blocks at the bottom of the window opening and check again with the level. Now you can insert the frame into the wall opening using wedges and washers.
• Once the frame is inserted and properly aligned, you can screw the frame firmly to the wall.
• You can now use a roller to attach the outer sealing film to the already attached sealing tape with the masonry. If there are still gaps, they should be filled with mounting foam.
• Finally, you can hang the windows and check their functionality. If you can open the windows in all directions without any problems, no further adjustments are needed.

Have Windows Installed by a Professional

Since a lot can go wrong during window installation, it’s advisable to leave the work to a professional. Accurate work is required when inserting and mounting the windows in the wall opening. The window must be properly aligned, and the distances between the frame, masonry, and window sill must be correct and identical. The vertical and horizontal position of the window must also be checked precisely. Small errors could soon lead to malfunctions and leaks. To prevent this, you shouldn’t skimp on window installation.

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Window Installation with RAL Assembly

RAL stands for the “German Institute for Quality Assurance and Labeling” and sets quality standards for various industries. RAL assembly also offers specific guidelines for window installation. This quality-assured installation follows the rules of the Energy Saving Ordinance (EnEV). 

RAL assembly focuses particularly on quality, durability, and energy efficiency. Therefore, it’s always advisable to hire an experienced and trained professional with RAL assembly knowledge for window replacement. If you’re unsure, you can inquire at a local specialist company.