Windows are one of the most vulnerable—and overlooked—parts of your home. They protect you from the elements, let in natural light, and play a major role in energy efficiency. However, over time, even the best windows can encounter issues. Three of the most common window issues homeowners face are cracked glass, fogging between panes, and stuck sashes.
Here’s how to fix these problems before they get worse—or more expensive.
Understanding Window Construction
Before diving into specific repairs, it’s important to understand basic window construction. Most modern windows feature double or triple-pane glass units sealed with weatherstripping and operated by various mechanisms depending on the window type.
Single-hung windows have a movable bottom sash, while double-hung windows allow both the top and bottom sashes to move. Casement windows swing outward on hinges, and sliding windows move horizontally along tracks.
1. Repairing Cracked Window Glass
Cracked glass isn’t just an eyesore—it can be dangerous and let in drafts, pests, and moisture. Whether it’s a small chip or a long fracture, your next steps depend on the size and type of crack.
For Small Cracks or Chips (Under 6 Inches)
You can often fix these yourself with a glass repair kit, which contains a clear epoxy resin to fill the crack. You can use this process to fix a small crack in your car windshield or any single-pane window. It is more of a temporary fix for a double-paned glass window.
Steps:
- Clean the glass – Use a glass cleaner and let the surface dry.
- Apply the resin – Follow the kit instructions to inject the resin into the crack. Use a small plastic applicator to push it in fully.
- Cure the resin – Place the curing strip (included) over the area and let it set in the sun or under a UV light.
- Remove excess resin – After curing, scrape off any hardened residue with a razor blade.
For Large Cracks or Broken Panes
If the crack is spreading or the glass is shattered, you’ll need to replace the pane entirely. This is especially true for double or triple-pane windows. DIY fixes can’t restore insulation. If you are dealing with a damaged frame, it is advisable to call a professional to help ensure proper sealing and maintain structural integrity.
Steps:
- Carefully remove the damaged glass – Wear gloves and eye protection.
- Measure and order a replacement pane – Local hardware stores or glass shops can cut one to size.
- Install the new pane – Remove the old glazing or putty, insert the new glass, and secure it with glazier’s points. Apply fresh glazing compound or caulk.
2. Fixing Foggy Windows
Foggy windows often mean the seal between the panes has failed. This lets moisture enter the airspace. You’ll see condensation, hazing, or even water droplets trapped between the panes.
Besides being unsightly, foggy windows lose their insulating value. That can lead to higher heating and cooling bills.
Understanding the Problem
Double- and triple-pane windows rely on sealed air spaces between glass panes for insulation. These spaces are filled with dry air or an inert gas and sealed with specialized materials. When these seals fail due to age, temperature fluctuations, or structural settling, moisture enters the space and condenses on the glass surfaces.
Option 1: Try defogging
Window defogging is a process where a technician creates a small hole in the glass. They remove the moisture and then seal the window. It’s faster and cheaper than a full replacement, but won’t restore the full insulating value. This is the best option for mild fogging.
Option 2: Replace the glass unit (IGU)
In most modern windows, you can replace the insulating glass unit (IGU) without changing the whole frame. This is likely the best option for moderate to severe fogging.
Steps:
- Contact a glass company to measure your existing IGU.
- Schedule a replacement. Technicians will remove the sash or stop, swap in the new IGU, and reseal it.
Option 3: Replace the entire window
If the window is old, warped, or has recurring condensation, it might be time to replace the whole unit. If you live in an older home, think about this. It’s especially important for homes with windows over 20 years old or that are dealing with recurring fog issues.
3. Fixing Stuck Window Sashes
If your window won’t open or close properly, it may be due to swollen wood, broken hardware, or paint buildup that has accumulated over the years. It’s a common problem in older double-hung or single-hung windows.
Diagnosing the Problem
Before attempting repairs, determine whether the sash is stuck due to paint, debris, swelling, or hardware issues. Gently try to move the sash while examining the tracks or channels for obvious obstructions. Look for paint buildup along the window frame edges or debris in the tracks.
How to free a stuck sash:
Step 1: Identify the cause
- Swollen wood? Usually happens after rain or humidity.
- Painted shut? Common with multiple coats over the years.
- Hardware issue? Broken springs, balances, or latches.
Step 2: Loosen it up
- For painted edges: Run a utility knife around the sash edges to break the seal. Use a putty knife or painter’s tool to gently pry the window loose. Be careful not to damage the frame.
- For swollen sashes: Wait for drier weather if possible. You can use a hairdryer or a fan to speed up the drying. Then sand lightly along the tight edges and apply a wax or silicone lubricant to the tracks.
- For hardware issues: Open the window as far as possible and inspect the side channels. For vinyl or aluminum windows, check for broken springs or balances. You may need to replace the balance system or sash guides (available at hardware stores).
If nothing works, call a window technician to prevent damage to the frame or glass.
Bonus tip: Clean and lubricate the tracks
Dust, dirt, and debris can accumulate in the tracks, making movement more difficult. Use a vacuum and a damp cloth to clean the tracks, then apply silicone spray or candle wax to improve motion.
When to Repair vs. Replace
| Problem | DIY Repair? | When to Replace |
| Small crack | Yes | If spreading or long |
| Foggy glass | Sometimes | If insulation is lost |
| Stuck sash | Yes | If the frame is warped or rotten |
| Rotten wood frame | No | Full frame replacement |
| Broken seal on IGU | No (DIY) | Replace the IGU or the window |
If your windows are over 15–20 years old and have ongoing problems, replacing them may save you money in the long run.
Conclusion
Fixing cracked, foggy, or stuck windows doesn’t always require a professional, and catching problems early can save you money.
Whether it’s a quick DIY epoxy repair, a simple hardware tune-up, or replacing an annoyingly foggy pane, knowing how to handle common issues will keep your home looking good, feeling comfortable, and running efficiently.
You might also be interested in: 5 DIY Window Maintenance Tips
