Symptoms
- Visible cracks or gaps in the caulk line around the frame
- Caulk pulling away from the wall or trim
- Drafts near the window edges
- Discoloration or mold in the caulk
Likely causes
- CommonNormal aging and UV exposureCaulk loses flexibility and shrinks over roughly 5–10 years outdoors.
- CommonBuilding movementSeasonal expansion and contraction stresses the caulk joint over time.
- PossibleWrong caulk type used originallyInterior caulk or a low-quality product used outdoors fails faster.
- PossibleMoisture trapped under the caulkWater that got behind the caulk before it fully cured can cause early peeling.
What to do
- Scrape out all cracked, peeling, or loose caulk with a caulk removal tool or flathead screwdriver.
- Clean the joint with a rag and, if greasy or dirty, a bit of mineral spirits, then let it dry fully.
- Apply painter's tape along both edges of the joint for a clean line if desired.
- Load a paintable exterior (or interior, if inside) caulk into a caulk gun and run a steady, even bead along the joint.
- Smooth the bead with a wet finger or caulk smoothing tool before it skins over.
- Remove the tape immediately while the caulk is still wet for the cleanest edge.
- Let it cure per the product's instructions (often 24 hours) before painting over it.
Tools and parts
- Caulk gun
- Caulk removal tool
- Painter's tape
Exterior window caulkSearch: “paintable exterior window caulk”
When to call a pro
Call a painter or handyman if you have many windows to reseal at once and want it done efficiently, or if there's rot behind the caulk.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.