The short answer is yes, you can use window film on double glazed windows, but with careful consideration. Certain types of film can cause thermal stress, leading to glass damage or seal failure, so understanding the properties of both your windows and the film is crucial before application.
Understanding Window Film & Double Glazing
What is Window Film?
Window film is a thin, multi-layered laminate applied to the interior or exterior of glass surfaces. It comes in various types, offering benefits like UV protection, glare reduction, privacy, security, and aesthetic enhancement. The composition varies depending on its purpose, but often includes polyester, adhesives, and coatings for specific functionalities.
What is Double Glazing?
Double glazing, also known as insulated glazing units (IGUs), comprises two panes of glass separated by a sealed air or gas-filled space. This construction improves thermal insulation, reduces noise transmission, and enhances energy efficiency. The gap between the panes acts as a barrier to heat transfer, keeping interiors warmer in winter and cooler in summer.
The Key Concerns: Thermal Stress and Seal Failure
The primary concern when applying window film to double glazed windows is the potential for thermal stress. Darker or highly reflective films absorb a significant amount of sunlight and convert it into heat. This heat can cause the outer pane of glass to expand more than the inner pane, creating stress within the glass itself. Over time, this stress can lead to cracks or even complete glass failure.
Another risk is seal failure in the IGU. The increased temperature differential can put extra pressure on the sealant that holds the two panes together. If the sealant is old, damaged, or of poor quality, it may degrade under the added stress, allowing moisture and air to enter the space between the panes. This results in condensation, fogging, and a loss of the IGU’s insulating properties.
Safe Window Film Options for Double Glazing
While thermal stress is a legitimate concern, not all window films are detrimental to double glazed windows. Certain films are specifically designed for use on IGUs and minimize the risk of damage.
These safer options typically include:
- Low-Emissivity (Low-E) Films: These films are designed to reflect infrared radiation (heat) without significantly absorbing solar energy. They help regulate temperature without causing excessive stress.
- Clear or Lightly Tinted Films: These films allow more light to pass through, reducing the amount of heat absorbed. They are suitable for applications where glare reduction or UV protection is desired without drastically changing the window’s appearance.
- Manufacturer-Approved Films: Some window manufacturers have tested and approved specific film brands for use on their products. Using these approved films ensures compatibility and may even protect your warranty.
Consulting a Professional is Crucial
Before applying any window film to your double glazed windows, it is highly recommended to consult with a professional window film installer or the window manufacturer. They can assess your specific windows, consider their age, condition, and orientation, and recommend the most suitable type of film. A professional installer will also have the expertise to apply the film correctly, minimizing the risk of damage and ensuring optimal performance.
FAQ: Your Questions Answered
FAQ 1: Will window film void my window warranty?
Potentially, yes. Applying unauthorized window film can void the warranty on your double glazed windows. Check your warranty documentation carefully or contact the window manufacturer to determine their specific policies regarding window film. Using manufacturer-approved films can often preserve your warranty.
FAQ 2: How can I tell if my double glazing is already under stress?
Look for signs of edge deletion (degradation of the sealant around the edges of the glass), condensation between the panes of glass, or any visible cracks in the glass. These are indications that your double glazing may already be compromised and could be further damaged by window film.
FAQ 3: Are darker films always more damaging to double glazing?
Generally, yes. Darker films absorb more solar energy and convert it into heat, which increases the risk of thermal stress. However, the specific composition and properties of the film also play a role. A darker low-E film might be safer than a light, highly reflective film.
FAQ 4: Can I apply window film to the exterior of my double glazed windows?
Applying film to the exterior is generally less risky than applying it to the interior because the heat is dissipated into the atmosphere more readily. However, exterior films are exposed to the elements and may have a shorter lifespan. The type of glass used (e.g., tempered, annealed) still needs to be considered.
FAQ 5: What is the best type of film for privacy on double glazed windows?
Frosted or reflective films are popular choices for privacy. Frosted films obscure the view from both sides, while reflective films provide a mirror-like appearance from the outside during the day. Consider a dual-reflective film to maintain some visibility from the inside.
FAQ 6: How do I clean window film applied to double glazed windows?
Use a soft cloth and a mild soap and water solution. Avoid abrasive cleaners, scouring pads, or ammonia-based products, as these can damage the film’s surface. Dry the film thoroughly with a clean, soft cloth.
FAQ 7: How long does window film typically last on double glazed windows?
The lifespan of window film depends on the quality of the film, the installation, and the environmental conditions. High-quality films can last 10-15 years or even longer if properly maintained.
FAQ 8: Can window film help reduce fading of furniture and carpets?
Yes, most window films, especially those with UV protection, can significantly reduce fading caused by sunlight. They block harmful UV rays, which are a major contributor to fading.
FAQ 9: Are there any DIY window film options that are safe for double glazing?
While DIY window film application is possible, it’s generally best left to professionals, especially with double glazing. If you choose to DIY, carefully select a film specifically designed for IGUs and follow the manufacturer’s instructions precisely. Thoroughly clean the glass and ensure proper installation to avoid air bubbles or other imperfections.
FAQ 10: What factors should I consider when choosing a window film installer?
Look for a reputable installer with experience working with double glazed windows. Ask for references and check online reviews. Ensure they are licensed and insured, and that they offer a warranty on their workmanship.
FAQ 11: Does the color of my double glazed windows affect the type of film I can use?
Yes, tinted or coated glass can impact the performance of window film. Darker tinted glass absorbs more heat, increasing the risk of thermal stress. Consult with a professional to determine the best film for your specific type of glass.
FAQ 12: What are the alternatives to window film for improving energy efficiency?
If you are concerned about the risks of window film, consider alternatives such as solar shades, blinds, curtains, or even replacing your existing windows with more energy-efficient models. These options can provide similar benefits without the potential for thermal stress.
By carefully considering the risks and benefits and seeking professional advice, you can safely and effectively use window film on your double glazed windows to achieve your desired goals.