The short answer
Simple Draft Test
One straightforward way to test window seals is the candle method. Close the window completely, then slowly pass a lit candle along the edges where the sash meets the frame. If the flame wavers or bends, air is moving through a gap, which often means the seal is broken.
Another option is to use a piece of paper. Close the window on a thin sheet of paper, then try to pull it out. If the paper slides out easily without resistance, the seal may not be pressing tightly. This test works well on double-hung windows.
Look for Condensation
Condensation between the glass panes is a clear indicator of a failed seal. If you see fog, moisture, or a milky film on the inside of a double-pane window, the seal that holds the insulating gas has likely broken. This allows outside air and moisture to enter the space between the panes.
Check the glass on a cool morning. If moisture appears inside the window, not just on the surface, the seal is compromised. You might also notice a slight haze that doesn't wipe off, which confirms the issue.
- Fog or condensation between panes
- Visible cracks or gaps in the sealant
- Drafts felt near the window edges
- Water stains on the sill or frame
- Difficulty opening or closing the window
- Increased outside noise coming through
Inspect the Sealant
Examine the rubber gasket or caulk around the window frame. Look for cracks, peeling, or areas where the material has pulled away from the glass or frame. Over time, weather exposure can cause these seals to degrade, especially on older windows.
Run your finger along the sealant to feel for soft spots or gaps. If the sealant is brittle or crumbling, it's likely failing. Also check the corners where the frame pieces meet, as these are common failure points.
Water Leak Test
To test for water leaks, you can gently spray water on the exterior of the window from a safe distance, such as from a garden hose. Have someone inside watch for any water seeping through the seal. This test works well on a dry day when you can see the results clearly.
Be cautious with this method, as excessive water could cause damage if the seal is severely broken. If you notice any water entering, stop immediately and address the issue. Water intrusion can lead to rot and mold if left unchecked.
When to Call the Pros
If your tests show signs of broken seals, it may be time to consider window replacement. A failing seal can lead to energy loss, drafts, and water damage inside your home. The pros can assess the condition and recommend a sensible course of action.
In some cases, the seal can be repaired, but if the window is old or the seal is beyond repair, replacement might be more practical. For water damage that has already occurred, a water damage inspection can help identify the extent of the problem and guide next steps.
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Call Now (801) 383-0232Frequently asked questions
How often should I test my window seals?
It's a good idea to check your window seals at least once a year, perhaps before the start of a new season. Regular checks can help you catch small issues before they become bigger problems. If you live in an area with extreme temperatures, more frequent checks may be helpful.
Can I fix a broken window seal myself?
Some minor sealant gaps can be filled with caulk, but if the seal between panes is broken, that's a more complex repair. In that case, the window unit may need to be replaced. For safety and effectiveness, consider having a professional assess the situation.
What other damage can broken window seals cause?
Broken seals can lead to drafts, higher energy bills, and condensation that promotes mold growth. Over time, water intrusion can damage window frames, walls, and flooring. If you notice water stains or dampness near windows, it's important to address the issue promptly.