Windows can develop cracks for various reasons, and not all are caused by obvious damage. While a clear impact—such as a rock or ball striking the glass—can break a pane, many cracks arise from less visible factors like environmental stresses or installation problems.
The most frequent causes include:
Impact damage from flying debris during storms or accidental collisions with furniture or tools;
Thermal stress resulting from rapid temperature changes that make the glass expand and contract unevenly;
Pressure variations due to changes in altitude, which can cause sealed double- or triple-pane glass units to crack when moved between different elevations;
Structural stress caused by foundation shifts or frames that have not been properly installed, placing strain on the glass;
Material defects, where tiny imperfections or weaknesses from the manufacturing process lead to cracks developing over time.
These are the most easily identifiable type of cracks. They occur when a solid object strikes the glass, creating a starburst or spiderweb-like pattern that spreads out from the impact site. Common sources include baseballs, hailstones, tools, rocks, or even birds. Risk level: High, as these cracks tend to grow rapidly and can compromise the entire glass pane. Recommended action: In most cases, the glass will need to be replaced.
These cracks usually start at a right angle from the edge of the glass and often curve or branch out. Common triggers include sudden temperature fluctuations, such as hot days followed by cool nights, or windows that receive uneven sunlight due to partial shading during the day. Risk level: Moderate, as these cracks can grow over time but generally do so at a slow pace. Recommended solution: Replace the glass with heat-strengthened or tempered glass to reduce the risk of recurrence. While thicker glass can be beneficial, using safety-rated glass is more crucial than simply increasing thickness.
cracks typically have an hourglass shape or an “S” curve and commonly appear in double- or triple-pane windows. They result from pressure imbalances caused by manufacturing defects or installation at incorrect elevations. Common causes include inadequate insulation, sealed windows subjected to significant altitude changes, or faulty factory sealing. Risk level: High, as these cracks frequently compromise the seal between glass panes, leading to decreased energy efficiency. Recommended solution: pressure equalization in insulating glass units using SWISSPACER Air
cracks begin along the outer edge of the window, often concealed beneath the trim, and move inward. Common causes include incorrect installation, stress on the window frame, or minor chips at the glass edge. Risk level: Variable, as these cracks can either remain stable or grow depending on external pressures. Recommended action: A complete glass pane replacement might be necessary, particularly if the window is subjected to ongoing stress.
Occasionally, cracks develop seemingly out of nowhere, without an obvious cause. Although often referred to as “spontaneous,” these cracks are usually stress-related or originate from edge flaws caused by hidden defects, frame distortion, or shifts in the building’s structure. Common causes include damage at the glass edges, temperature fluctuations, or manufacturing faults. Risk level: Uncertain, as these cracks may signal underlying problems. Recommended action: A thorough professional assessment is necessary to decide if repair or complete window replacement is needed.
Cracked windows might seem like a minor problem initially, but if ignored, they can cause significant issues. Firstly, they present a safety risk: a small crack can quickly expand, leading to shattered glass and a higher chance of injury. In addition to safety concerns, cracked windows reduce your home’s energy efficiency. When the seal on an insulated window is broken, conditioned air can escape, and moisture can enter. Even tiny cracks allowing water in can eventually cause mold growth, wood rot, and damage to your interior. This is why it’s crucial to address any cracks promptly, no matter how insignificant they may seem.
Although it’s impossible to prevent every crack, there are effective steps you can take to lower the risk. Choosing high-quality, strong glass with improved insulation can make your windows more resilient against temperature changes and minor impacts. Using window coverings to control sun exposure helps prevent uneven heating that can cause thermal cracks. Keeping trees trimmed and securing outdoor furniture reduces the likelihood of damage from storms. Most importantly, having your windows installed by professionals ensures a proper fit, preventing pressure or edge cracks caused by poor installation.
The appropriate solution varies based on the crack’s type and severity. Minor surface scratches or small cracks in single-pane glass can often be fixed using clear epoxy or resin repair kits. However, cracks in double-pane or structural glass typically need a complete replacement, especially if the seal is compromised or the crack is expanding. If you’re unsure, it’s best to seek a professional evaluation. Rite Window offers expert inspections and can advise you on the most effective repair or replacement options.
SWISSPACER Air is a new product essential for many users of insulated glass units. Its primary function is to regulate the pressure between the glass panes and the surrounding environment. It protects the glass from cracking and prevents the entire unit from warping during transportation and everyday use.
Insulated glass units are becoming increasingly popular due to their ability to significantly enhance thermal and acoustic insulation. However, when transported by airplane or in areas with large altitude changes, pressure differences can develop between the inside of the glass and the surrounding environment. These variations can also be caused by changing weather conditions. Such pressure differences may lead to glass cracking and distortion of the units. SWISSPACER Air effectively addresses these issues.
The SWISSPACER Air spacer frame balances the pressure differences between the inside of an insulated glass unit and the surrounding atmosphere where the glass is installed. This ensures that production, transportation, and installation—even at varying altitudes—can occur without causing mechanical stresses caused by the glass panes deforming due to pressure disparities inside and outside the unit. When glass panes bend, it creates stress along the edges of the insulated glass, which can lead to damage such as seal failure or even cracking of the glass panes.
One of the advantages of SWISSPACER Air is that it takes significantly less time to install in insulating glass units compared to the competing method using capillary tubes.
The new solution is not only useful in the production process – SWISSPACER Air can be installed in insulating glass units where standard SWISSPACER spacers were previously installed.
