1300 RETROFIT (738-763)
REQUEST A QUOTE
REQUEST A QUOTE
1300 RETROFIT (738-763)

What Is the Lifespan of Double-Glazed Windows?

What Is the Lifespan of Double-Glazed Windows?

What Is the Lifespan of Double-Glazed Windows?

Posted on in Blog

Double-glazed windows have become a key element in modern homes, offering noise reduction, energy efficiency and improved all year-round comfort. However, one question many homeowners ask before investing in double glazing is: How long do double-glazed windows last?

The lifespan of double-glazed windows can vary depending on factors such as materials, installation quality, climate and maintenance. We break down how long double-glazing lasts, the signs of wear and tear and how you can extend the life of your windows for the best long-term value.

How Long Do Double-Glazed Windows Last?

On average, high-quality double-glazed windows last between 20 to 35 years. However, this depends on multiple factors, including:

  • The quality of materials (glass, gas fill, and frame type).
  • The effectiveness of the seal that prevents condensation and gas leakage.
  • Exposure to extreme weather conditions (heat, cold, moisture, or strong winds).
  • Proper installation ensuring no gaps or weaknesses in the structure.
  • Regular maintenance and care to prevent deterioration.

While some lower end double glazed windows may only last 10-15 years, well-maintained, premium-quality installations can function effectively for 30 years or more.

Factors That Affect the Lifespan of Double-Glazed Windows

The Quality of the Glass and Gas Fill

The two panes of glass in double-glazed windows are separated by an air gap or an insulating gas (such as argon or krypton). This gas acts as a thermal barrier, helping to regulate indoor temperatures.

Over time, the gas inside the panes may slowly leak, reducing the insulation effectiveness. High-quality double glazing with properly sealed units will minimise gas loss and extend longevity.

The Strength of the Window Seal

The seal around double-glazed windows are very important in keeping moisture out and gas in. If the seal weakens, it can lead to condensation between the panes, which reduces insulation and visibility. Seals may degrade faster in areas with high humidity, strong UV exposure or extreme temperature fluctuations.

Frame Material and Durability

The type of window frame you choose impacts both performance and longevity. Different materials have different lifespans:

Frame Material Average Lifespan Pros Cons
uPVC 20–30 years Affordable, low maintenance, energy-efficient. May discolour over time.
Aluminium 30–40 years Strong, durable, modern look. Conducts heat unless thermally broken.
Timber 30–50 years Classic appearance, great insulation. Requires regular maintenance.

 

Among these, uPVC and aluminium are the most common choices for modern double-glazed windows due to their balance of durability, efficiency and affordability.

Installation Quality

Even the highest-quality double-glazed windows won’t last if they’re not installed correctly. Poor installation can cause:

  • Gaps and poor seals, leading to air leaks and condensation.
  • Uneven fitting, causing stress on the frame and reducing its longevity.
  • Poor drainage, allowing water to pool and degrade materials.

Choosing a reputable installer ensures that your windows perform optimally for their full lifespan.

Signs That Double-Glazed Windows Need Replacing

Reality is, even the best double-glazed windows won’t last forever. Here are the common signs that indicate they might need replacing:

  • Condensation Between the Panes – This is a sign that the seal has failed, allowing moisture to enter.
  • Draughts or Air Leaks – If you feel cold air entering around your windows, it means the insulation is no longer effective.
  • Increased Energy Bills – Poor insulation means your heating or cooling system works harder, leading to higher energy costs.
  • Fading Furniture or Flooring – Older glass may lose its UV protection, causing sun damage indoor furniture and flooring.
  • Cracks or Damage to Frames – This can allow water to seep in, leading to further deterioration.
  • Difficulty Opening or Closing Windows – Warped frames or failing mechanisms may indicate aging materials.

How to Extend the Lifespan of Your Double-Glazed Windows 

With proper care, you can maximise the longevity of your double glazing. Here’s how:

Regular Cleaning and Maintenance

  • Clean window frames and glass with mild soapy water to prevent dirt build-up.
  • Avoid harsh chemicals that could degrade seals and coatings.
  • Inspect seals and hinges annually for signs of wear or cracks.

Protect the Seals

    • Reapply sealant if you notice any gaps forming.
    • Keep moisture away by ensuring adequate ventilation in your home.

    Repair Instead of Replace

      If only a small part of your window is damaged, you may not need a full replacement. Options include:

      • Replacing the seals if condensation appears.
      • Regassing the air gap if insulation is reduced.
      • Refinishing or repainting frames to prevent further deterioration.

      Consider Retrofit Double Glazing

        If your existing windows are in good condition, retrofit double glazing can be a cost-effective way to extend their lifespan without a full replacement.

        Retrofit double glazing involves adding a secondary glazing system to existing window reveal, allowing a maximum air cavity for optimal result. This solution provides similar benefits to new double-glazed units in a more cost-effective way, and could potentially add another 15 to 20 years of life to your existing windows.

        Why Choose Magnetite Australia?

        For homeowners looking for a cost-effective way to improve thermal insulation and soundproofing, Magnetite offers  a range of secondary glazing solutions that will upgrade performance as well as extend the life of your existing windows.

        Unlike traditional double glazing, Magnetite’s retrofit system provides thermal and noise insulation without needing window replacements, making it an ideal choice for:

        • Heritage properties that require minimal impact on the building façade.
        • Apartments and commercial spaces where full window replacements are impractical.
        • Homeowners looking for an affordable and energy-efficient solution.

        With over 27 years of experience, Magnetite Australia is committed to providing long-lasting solutions that improve comfort, energy efficiency and noise reduction. All Magnetite installation comes with a 7-year warranty for your peace of mind. Whether you’re looking to reduce noise or improve thermal insulation in your home, Magnetite offers tailored solutions to fits your existing window and provide the best possible outcome.

        Get in touch today to explore your options!

        1. Conduction
          Heat moving through an object (i.e. heat will travel through an aluminium, or steel frame more easily than through a timber or PVC frame).
        2. Radiant heat
          Heat from the direct sun. It can pass through space until reflected or absorbed.
        3. Convection
          Heat flow resulting from air movement e.g. either 'natural' convection - warm air rises, or 'forced' convection - a breeze by a window, both can result in a draught by a window.
        4. Infiltration
          Air leaks around the frame, around the window sash and through the gaps in the movable window parts.

        When evaluating your options to improve the thermal performance of your windows, the following double glazing key performance criteria should be considered:

        • U-Value (Uw) represents heat transfer through a window, irrespective of direct sunlight. The lower a window’s U-Value, the better the insulation performance.
        • Solar Heat Gain Coefficient (SHGC) measures the solar energy that passes through glazing. The lower the SHGC, the less solar heat is transmitted through a window.
        • Air Infiltration or leakage measures the rate at which air passes through gaps in window joins and seals. The lower the air infiltration, the better a window’s energy performance.

        The Window Energy Rating Scheme (WERS) Thermal Performance

        Aluminium Frame Windows

        Glazing Type Cooling Stars Heating Stars Cool% Heat% Uw SHGC
        Single glazed 3mm clear glass* half blue star red starhalf red star 7.4 0.77
        Single glazed 3mm clear glass &
        4.5mm Magnetite        		 blue starblue starhalf blue star red starred starred starred starred starhalf red star 35% 59% 2.9 0.67

        Timber Frame Windows

        Glazing Type Cooling Stars Heating Stars Cool% Heat% Uw SHGC
        Single glazed 3mm clear glass* blue starhalf blue star red starred starred starhalf red star 20% 28% 5.5 0.69
        Single glazed 3mm clear glass &
        4.5mm Magnetite        		 blue starblue starhalf blue star red starred starred starred starred starred star 37% 61% 2.6 0.66
        Single glazed 3mm clear glass with
        Solartite** and 4.5mm Magnetite        		 blue starblue starblue starblue starblue starblue starhalf blue star red starred starred starred starhalf red star 76% 45% 1.8 0.20

         

        *WERS standard typical industry window
        **Solartite is a range of high performance window film. The window tested above has Solartite’s low-e film.

        Magnetite vs Traditional Double Glazing – What the experts says

        Winter - the ideal situation is to let in as much of the sun's heat and then trap it inside to maintain a comfortable environment in your home or office. This will also significantly reduce heating costs and saves you money. The ideal window for winter will have a high SHGC to let the sun's heat in and a low U-Value to prevent the heat from escaping. Clear windows without shading films are better suited for winter climates.

        Compared with traditional double-glazing, Magnetite’s double-glazing solution can provide better results during winter or for cold climate areas such as Canberra, the Adelaide Hills and Blue Mountains.

        Magnetite's clear acrylic window panels allow the direct heat from the sun's rays to enter the building and once inside, Magnetite's superior magnetic seals retain the heat, giving Magnetite an advantage over conventional operating windows.

        Glazing Type Cooling Stars Heating Stars Cool% Heat% Uw SHGC AI
        Double Glazed 3mm clear glass/12mm air
        gap/3mm clear glass IGU (Insulated Glass Unit)*        		 blue starblue starhalf blue star red starred starred starred starred starhalf red star 40% 55% 3.0 0.61 5.0
        Single glazed 3mm clear glass &
        4.5mm Magnetite        		 blue starblue starhalf blue star red starred starred starred starred starred star 37% 61% 2.6 0.66 0.5

         

        *WERS standard typical industry window

        Summer - the ideal situation is to minimize the heat coming in from outside and prevent the cool air inside from escaping through the window. This will make your home more comfortable and reduce your air-conditioning costs. The ideal window for summer, or for a large west-facing window, will have a low SHGC to limit the heat from the sun's direct rays, as well as, a low U-Value to prevent the heat in the air outside from moving through the window and warming the cool conditioned air inside. It is better to have a shading film on the first (outer) glass pane to limit the heat that enters the double glazed unit.

        The combination of Magnetite retrofit double glazing and Solartite outperforms the traditional insulated glass unit for hot climate. Magnetite fit over an existing window with reflective film will give better summer heat control than a double-glazed window with supertoned glass.

        The Magnetite system stops the conduction and convection of heat better than glass windows giving superior results for summer conditions. Combined with a film or a shading device, Magnetite is the ideal solution for the hot Australian conditions.

        Glazing Type Cooling Stars Heating Stars Cool% Heat% Uw SHGC AI
        Double Glazed 5mm Supertoned glass/6mm
        air gap/5mm clear glass IGU (Insulated Glass Unit)*        		 blue starblue starblue starhalf blue star red starred starred starred starhalf red star 54% 425% 3.30 0.461 5.0
        Single glazed 3mm glass Solartite**
        and 4.5mm Magnetite        		 blue starblue starblue starblue starblue starhalf blue star red starred starred starred star 73% 38% 2.4 0.19 0.5

         

        *WERS standard typical industry window
        **Solartite is a range of high performance window film. The window tested above has Solartite’s low-e film.

        Click here to view pdf version of Magnetite WERS test result.

        Noise Reduction Technical Data and Results

        Proven Results

        Noise pollution is one the biggest problems faced in the cities today, particularly in a high-density living. Unwanted noise can be responsible for sleep loss and lack of concentration. This can lead to a deterioration of health through increased stress levels, headaches, high blood pressure and loss of hearing.

        Noise penetrates windows through leaky seals or vibrations through the window structure. To reduce noise, a window should minimise air infiltration, hold enough weight to limit vibration and allow a large air cavity. This cavity, or air gap, is the key to secondary glazing.

        Expert Advice:

        CSIRO Research by John Davy shown an air cavity can effectively enhance sound insulation performance. The larger the air cavity the more noise the window system can reduce. Results show a wide air gap of 100-125mm will improve sound insulation by an average of 7dB(A) more than windows with a narrow gap of 8-13mm.

        Window or Glass Door Type Total Glass Thickness (mm) Air Cavity Thickness (mm) Sound Insulation (dB)
        Single Glaze 3mm 3 0 23
        Single Glaze 6mm 6 0 27
        Double Glaze Narrow Gap 9-12 8-13 31
        Double Glaze Wide Gap 9-12 100-125 38

         

        The human ear is less sensitive to low frequency sound. According to a study released by the CSIRO, the human ear needs a change of 3dB to detect a difference in noise levels and the human ear perceives a change of 10dB as a doubling or halving of the noise level.

        If you double the thickness of glass in a window the noise level will decrease by 3dB the least amount possible to make a difference. If the glass is laminated there is no perceived difference in noise reduction.

        National Acoustic Laboratory Testing:

        Working with the principles of noise transfer, Magnetite® and Soundtite are designed for high performance, which is achieved by combining air tight seals with the ability to maximize an air cavity and the flexibility to vary glazing thickness to suit. Magnetite® is excellent at reducing general noise such as busy roads, commuter trains and noisy neighbours. Whereas, Soundtite works well to combat low frequencies noise such as garbage truck, freight trains or airplane during take-off and landing.

        Test Code Material Tested Rw* Improvement
        ATF 707 (test window) Aluminium sliding window, 3mm float glass with mohair seals 23 N/A
        ATF 709 Test window, 100mm air gap and Magnetite System (4.5mm acrylic panel) 35 52%
        ATF 1507 Test window, 100mm air gap and Magnetite System (10.0mm acrylic panel) 39 70%
        ATF 817 Test window, 100mm air gap and Soundtite (6.38mm laminated glass) 41 78%

         

        *The Weighted Sound Reduction Index (Rw) is a measure for sound insulation performance of a single building element such as windows. The higher the Rw rating, the better the sound insulation.