How to Recaulk Exterior Windows: Stopping Air & Water Infiltration

## Why Exterior Caulking Fails Exterior caulking joints between your window frame and brick, stucco, or siding endure severe thermal expansion cycles, UV radiation, and rain. Over 5 to 7 years, cheap acrylic caulk hardens, shrinks, and cracks, allowing rainwater to penetrate behind wall claddings. ### The Right Caulking Material: - **Avoid:** Standard interior latex painter's caulk (cracks outdoors quickly). - **Use:** 100% Silicone or Advanced Polymer Polyurethane sealant designed for ±50% joint movement. ### Step-by-Step Execution: 1. **Scrape and Clean:** Use a 5-in-1 painters tool or caulk scraper to strip all old sealant down to bare siding and frame. Wipe the joint with isopropyl alcohol. 2. **Insert Backer Rod:** If the gap is deeper than 3/8-inch, insert closed-cell foam backer rod to prevent three-point adhesion failure. 3. **Cut Caulk Tip:** Cut the cartridge nozzle at a 45-degree angle to produce a bead matching your joint width (typically 1/4-inch). 4. **Apply Uniform Bead:** Hold the gun at 45 degrees, pull steadily along the joint, and smooth the bead with a caulk finishing tool or a gloved finger dipped in soapy water. Need whole-home exterior window resealing? Connect with ServiceFind Windows Pro for a comprehensive **Fair Quote**.