Support Broken seal and why they fail

A Broken seal

Why do they break and what can we do?

At Double glazing window seals break due to a mix of natural aging, environmental stress, installation issues, and physical damage. Heres a clear breakdown of the main reasons: 1. Natural Aging & Material Degradation Seals are usually made from rubber, silicone, or foam, which lose elasticity over time. Exposure to oxygen, heat, and cold causes them to harden, shrink, crack, or become brittle. This is the most common cause, typically happening after 10–20 years. UV rays from sunlight break down the chemical structure of seal materials, speeding up wear and making them prone to splitting. 2. Temperature & Weather Changes Expansion and contraction: When temperatures rise and fall, the glass, frame, and seal expand and contract at different rates. This constant movement puts stress on the seal, eventually causing it to pull away or tear. Moisture and frost: Water can seep into tiny gaps in the seal; when it freezes, it expands and widens cracks. Persistent dampness also accelerates rotting or degradation of rubber seals. Strong winds and storms: Pressure changes or physical buffeting can strain the seal, especially if the window is already slightly worn.

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3. Poor Installation or Manufacturing Defects If the seal was not fitted correctly, was stretched too tight, or had gaps during installation, it will fail much sooner. Low-quality materials or faulty manufacturing (e.g., uneven thickness, weak bonding) mean the seal cannot withstand normal use or weather conditions. Incorrect spacing between the glass panes puts extra pressure on the seal edges. 4. Physical Stress & Damage Forced operation: Slamming windows shut, forcing them open/closed, or leaning on them bends the frame and stretches or tears the seal. Impact damage: Knocks, scratches, or bumps (from furniture, cleaning, or accidents) create weak points that quickly turn into full breaks. Frame movement: If the building settles, shifts, or the frame warps, the glass panes move out of alignment, pulling the seal apart. 5. Lack of Maintenance Dirt, grit, and debris trapped in the seal groove act like sandpaper, wearing down the material over time. Dry, unlubricated seals become stiff and crack easily; regular cleaning and gentle conditioning can extend their life, but neglect speeds up failure. When the seal breaks, the insulating gas between the panes escapes, moisture gets trapped inside, and youll often see fog, condensation, or water droplets between the glass.