Choose a high-quality exterior-grade caulk suitable for windows
Clean the window frame and surrounding surfaces
Remove old, cracked, or loose caulk
Let the area dry completely
Cut the caulk tube tip at a 45-degree angle
Puncture the inner seal of the tube
Load the tube into a caulk gun
Apply painter’s tape along both sides of the joint if desired
Hold the gun at a steady angle
Apply a continuous bead of caulk along the gap
Keep the bead even and consistent
Smooth the bead with a caulk tool or a wet finger
Remove painter’s tape before the caulk skins over
Wipe away excess caulk immediately
Allow the caulk to cure according to the product instructions
Inspect for missed gaps and touch up if needed