Caulk Windows and Doors
Why It Matters
Caulk gaps let rain and air into your walls. Sealing them prevents water damage and keeps your energy bills in check.
Quick Guide
- 1
Gather your tools and materials
You'll need: Caulk gun, Putty knife. Materials required: Exterior silicone or polyurethane caulk.
- 2
Perform the caulk windows and doors
Apply or replace exterior caulk around windows, doors, and where siding meets trim.
- 3
Verify and clean up
Check that the work was completed correctly and clean up your workspace.
Tools & Materials
Tools
- Caulk gun
- Putty knife
Materials
- Exterior silicone or polyurethane caulk
Community Tips
Cut the caulk tube nozzle at a 45-degree angle and size the opening to match the gap width—typically 1/8 inch for standard window frames—to avoid overfilling and messy cleanup. GE Silproof Advanced ($6-10) maintains a clean bead without requiring excessive tooling when applied at the correct angle and speed.
Never caulk over dirt, old paint, or failed caulk; remove existing material with a putty knife or oscillating tool first, as new caulk will fail prematurely if it bonds to a compromised surface rather than direct contact with wood or trim.
Polyurethane caulks like Sikaflex SL Polyurethane ($12-18 per tube) cost nearly double standard silicone but expand minimally during cure and resist UV degradation better, making them the economical choice for south-facing windows that endure intense sun exposure over 10+ years. ---