The short answer
Why Sealing Windows Matters
Sealing your windows before the rainy season helps keep water out of your home. Leaks around windows can lead to damp walls, peeling paint, and even structural issues over time. In a coastal climate, the combination of rain and wind can push water into the smallest cracks.
A proper seal also improves energy efficiency by reducing drafts. You can often spot problem areas by looking for dried caulk, gaps, or water stains on the wall below. Checking your windows in late summer gives you time to fix issues before the rainy season.
What You Need to Check First
Before applying any sealant, inspect the window frame and the surrounding wall. Look for signs of rot, soft wood, or old, crumbling caulk. If the frame is damaged, sealing over it will not solve the problem, and water will find its way in anyway.
Also check the glass and the flashing above the window. Flashing is the metal or plastic piece that directs water away from the top of the window. If it is loose or missing, that is a separate repair. A quick test: on a dry day, run your hand along the edges to feel for drafts.
- Clean the frame and sill with a brush and mild soap
- Remove old caulk with a putty knife or scraper
- Check for gaps wider than a pencil line
- Look for water stains or soft spots on the wall below
- Test the window operation to ensure it closes fully
How to Apply New Caulk
Choose a high-quality exterior caulk that is labeled for windows and doors. Silicone or a hybrid sealant works well because it stays flexible and resists water. Cut the nozzle at a 45-degree angle and load the tube into a caulk gun. Run a smooth bead along the seam where the frame meets the wall.
Smooth the bead with a wet finger or a small tool to press it into the gap. Let it cure according to the label before painting, if painting is needed. For the moving parts of the window, use weatherstripping tape or a V-shaped strip that compresses when the window closes.
- Work in dry weather, ideally above 50 degrees
- Apply the caulk in one continuous bead
- Press the sealant into the gap, not just on top
- Use weatherstripping on the sash and the bottom edge
- Check the seal from outside if you have a ladder
What to Do If Water Still Gets In
Sometimes sealing the window is not enough. Water can enter through the wall above the window, through a roof leak, or from poor drainage around the foundation. If you see water on the floor or the wall after a storm, look for the source beyond the window itself.
If the leak is persistent and you cannot find the cause, a water damage inspection can help identify the entry point. The pros use moisture meters and other tools to locate hidden water. They can also check if the damage has spread to the framing or drywall. Acting quickly reduces the risk of mold.
When to Consider Window Replacement
Sealing works for minor gaps, but if the window frame is rotted, the glass is cracked, or the window is old and drafty, replacement may be the better choice. New windows often come with better weatherstripping and insulation, which can reduce future leaks.
Replacing a window is a bigger job that involves removing the old unit and installing a new one. If you are not comfortable with that, a window replacement service can handle it. The cost depends on the window size, the material, and the labor in your area.
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Water keeps spreading into floors and walls, so it is worth acting early. Calls are answered 24/7.
Call Now (617) 404-2753Frequently asked questions
How often should I reseal my windows?
Exterior caulk typically lasts 5 to 10 years, but weather and sun exposure can shorten that. Check your seals each year before the rainy season. If the caulk is cracked, brittle, or pulling away, replace it even if it has not leaked yet.
Can I seal windows from the inside?
Interior sealing can help with air drafts, but it does not stop water from entering. Water needs to be stopped on the exterior side. Use interior caulk only as a temporary measure, and always address the outside seal for a lasting fix.
What if my window leaks after I seal it?
If water still appears after you seal the window, the leak may come from elsewhere, such as the roof, siding, or flashing. A water damage inspection can pinpoint the source. In the meantime, dry the area and keep an eye on the window to prevent mold growth.