Improving a "blown window" primarily involves addressing the visible fogging or condensation that occurs between the glass panes. This fogging is a clear sign that the seal of your insulated glass unit (IGU) has failed, allowing moisture-laden air to enter the gap that was originally filled with dry air or an inert gas for insulation. Restoring the window's clarity and thermal efficiency requires repairing the failed seal and cleaning the internal surfaces.
Understanding Blown Windows
A blown window is essentially a double or triple-pane window where the hermetic seal around the edges of the insulated glass unit (IGU) has broken. This failure allows moisture and sometimes dirt or debris to enter the space between the panes, leading to:
- Visible condensation or fogging: This is the most common symptom, making the window look dirty or cloudy from the inside.
- Reduced energy efficiency: The insulating gas or dry air has escaped, and the moisture inside conducts heat more readily, decreasing the window's thermal performance.
- Obscured view: The fogging can significantly hinder visibility.
Improving Blown Windows Through Repair
While replacement is an option for blown windows, they can often be improved through a repair process that targets the failed seal and cleans the interior space. This method aims to restore the window's clarity and some of its insulating properties.
Based on standard repair techniques for failed insulated glass units, the process involves several key steps:
The Repair Process: Step-by-Step
Repairing a blown window unit is a detailed process that requires careful handling of the glass and frame components. Here are the fundamental steps involved:
- Remove the affected window unit from its frame.
- Practical Insight: This step requires detaching the entire glass unit from the window sash or frame it sits within. This might involve removing glazing beads or fasteners.
- Disassemble the unit, separating the individual glass panes.
- Practical Insight: The panes are typically held together by a spacer bar and sealant. Careful separation is needed to avoid breaking the glass.
- Clean and dry each pane thoroughly to eliminate any moisture or debris.
- Practical Insight: Specialized cleaning agents may be used for internal glass surfaces. Ensuring they are perfectly dry is crucial before reassembly.
- Replace the damaged sealing materials.
- Practical Insight: The old spacer bar and sealants are removed and replaced with new materials designed to create a strong, airtight, and watertight seal. Desiccant material within the spacer is also typically replaced or reactivated.
- Reassemble the window unit and reinstall it securely.
- Practical Insight: The panes, new spacer, and new sealants are put back together, and the revitalized IGU is re-inserted into the window sash or frame.
This repair process directly addresses the cause of the "blown" issue by eliminating the trapped moisture and restoring the seal.
Why Repair Works
By following these steps, the repair process:
- Removes the cosmetic issue: Cleaning eliminates the unsightly fogging and debris between the panes.
- Restores the insulating barrier: Replacing the seal and potentially refilling with dry air or gas re-establishes the insulating layer that was compromised.
- Extends window lifespan: Repair can be a cost-effective alternative to full window replacement if the frame is still in good condition.
Considering Alternatives
While repair is a viable way to improve blown windows as described above, full replacement of the insulated glass unit or even the entire window is another common solution, especially if the window is old, the frame is deteriorating, or you are seeking significant energy efficiency upgrades. However, the process detailed above is a direct method for improving the existing blown unit itself.
Repair Process Summary
Here is a summary of the key steps for improving a blown window unit through repair:
| Step | Action |
|---|---|
| 1. Removal | Take the IGU out of its frame. |
| 2. Disassembly | Separate the glass panes. |
| 3. Cleaning & Drying | Clean internal glass surfaces. |
| 4. Resealing | Replace old seals/spacer with new ones. |
| 5. Reassembly & Install | Put the unit back together and reinstall. |
By undertaking this repair process, you can effectively improve the appearance and performance of blown windows.
