Resealing double pane windows is a critical maintenance task that homeowners often overlook until problems become apparent. These windows, also known as insulated glass units (IGUs), consist of two glass panels separated by a spacer and sealed together with an airtight perimeter seal. This construction creates an insulating air space that significantly improves thermal efficiency compared to single-pane windows. However, when the seal fails, moisture infiltrates the space between the panes, leading to condensation, reduced insulation properties, and compromised visibility. Understanding the process of resealing double pane windows can help you determine whether repair or replacement is the most cost-effective solution for your situation.
The primary indicator that your double pane windows need resealing is the appearance of condensation or fogging between the glass layers. This occurs when the hermetic seal around the perimeter of the insulated glass unit becomes compromised, allowing moisture-laden air to enter the space between the panes. When the temperature changes, this moisture condenses on the interior glass surfaces, creating a foggy appearance that cannot be wiped away from the outside. Other signs include visible mineral deposits or etching on the interior glass surfaces from evaporated condensation, drafts around the window frame despite the window being closed, and noticeably reduced energy efficiency in your home.
Before deciding to reseal your double pane windows, it’s important to understand why the seals fail in the first place. Several factors contribute to seal degradation:
- Age: Most window seals have a lifespan of 10-20 years, depending on the quality of materials and installation.
- Weather Exposure: Constant exposure to UV radiation, temperature fluctuations, and moisture accelerates seal deterioration.
- Poor Installation: Windows that were improperly installed may have compromised seals from the beginning.
- Frame Movement: Settlement of the building or expansion and contraction of window frames can stress the seals.
- Chemical Exposure: Harsh cleaning chemicals can degrade some types of sealants over time.
The process of resealing double pane windows typically involves one of two approaches: applying an external sealant or replacing the entire insulated glass unit. For minor seal issues that are caught early, sometimes applying a specialized external sealant around the perimeter of the glass unit can provide a temporary solution. However, this method is generally not recommended as a long-term fix, as it doesn’t address moisture already trapped between the panes or potential damage to the desiccant material inside the unit that absorbs moisture.
For a permanent solution, replacing the insulated glass unit is typically the most effective approach. This process involves:
- Carefully removing the window sash from the frame
- Extracting the failed glass unit from the sash
- Thoroughly cleaning the channel where the glass sits
- Installing a new insulated glass unit
- Applying new sealants and reinstalling the sash
While this might sound straightforward, the process requires specific tools and expertise to ensure a proper, lasting seal. Many homeowners opt to hire professionals for this task, though experienced DIY enthusiasts with the right tools can attempt it themselves.
If you’re considering DIY resealing of double pane windows, you’ll need to gather the appropriate materials and tools:
- Replacement insulated glass unit (correct size and thickness)
- Glazing points or clips
- Glazing compound or silicone sealant specifically designed for windows
- Glass cleaner and lint-free cloths
- Putty knife or glazing tool
- Safety gloves and goggles
- Wooden blocks or setting blocks for proper alignment
The step-by-step process for replacing a sealed double pane unit begins with careful removal of the window sash. For double-hung windows, this typically involves releasing the spring mechanisms or removing parting beads. Once the sash is removed and placed on a stable work surface, you’ll need to remove the glazing stops or vinyl glazing beads that hold the glass in place. These are often carefully pried away with a putty knife or small pry bar to avoid breakage.
With the retaining pieces removed, the failed glass unit can be lifted out of the sash frame. This is the time to thoroughly clean the channel where the new glass will sit, removing all old putty, sealant, and debris. Any rot in wooden sashes should be repaired before proceeding. The new insulated glass unit is then placed into the channel, positioned on setting blocks to ensure proper alignment and drainage. New glazing points are installed to secure the glass, and the glazing stops or beads are replaced. Finally, a high-quality sealant is applied around the perimeter where the glass meets the sash to create a weather-tight seal.
For homeowners who aren’t comfortable with this process or whose windows have additional issues, professional window repair services offer several advantages. Experienced technicians have the proper tools and knowledge to handle various window types and potential complications. They can accurately assess whether resealing is appropriate or if full window replacement would be more cost-effective in the long run. Many professionals also offer warranties on their work, providing peace of mind that the repair will last.
The cost of resealing double pane windows varies significantly based on several factors:
- Window Size: Larger windows require larger glass units, increasing material costs
- Window Type: Specialty shapes or custom windows are more expensive to repair
- Glass Features: Windows with low-E coatings, argon gas fills, or tempered glass cost more to replace
- Labor Costs: Varies by region and complexity of the installation
- Number of Windows: Multiple window repairs may qualify for volume discounts
On average, homeowners can expect to pay between $100 and $400 per window for professional glass unit replacement, compared to $50-$150 for DIY approaches (primarily the cost of the new insulated glass unit). While the DIY approach appears more economical initially, improper installation can lead to rapid seal failure, potentially costing more in the long run.
Preventive measures can extend the life of your double pane window seals significantly. Regular inspection of seals for early signs of cracking or separation allows for early intervention. Using gentle cleaning methods and avoiding harsh chemicals that can degrade sealants helps preserve their integrity. Ensuring proper drainage around the window frame prevents water accumulation that could compromise seals. In some cases, applying UV-protective film to windows can reduce sun damage to perimeter seals. Maintaining consistent indoor humidity levels reduces the stress on seals caused by extreme pressure differences.
When deciding between resealing double pane windows and complete window replacement, consider the age and overall condition of your existing windows. If your windows are relatively new and otherwise in good condition, resealing by replacing the insulated glass units is typically the most cost-effective approach. However, if your windows are older, showing signs of frame deterioration, or have outdated designs that affect energy efficiency, full window replacement might offer better long-term value through improved energy savings and reduced maintenance needs.
Modern advancements in window technology have led to more durable sealing options. Some manufacturers now offer dual-seal systems with both primary and secondary seals for enhanced protection against failure. Warm edge spacer technology reduces heat transfer at the glass edge, minimizing condensation issues and extending seal life. Improved desiccant materials better absorb moisture that enters the air space, providing additional protection against fogging even if minor seal compromise occurs.
In conclusion, resealing double pane windows is a valuable process that can restore clarity, efficiency, and comfort to your home when properly executed. Whether you choose DIY repair or professional service depends on your skill level, the complexity of the window system, and your budget considerations. Regular maintenance and early intervention at the first signs of seal failure can prevent more extensive damage and higher repair costs down the road. By understanding the process, materials, and options available for resealing double pane windows, you can make an informed decision that preserves both your windows and your investment in your home.