| Material | Rating | Review | | :--- | :--- | :--- | | | ⭐⭐ | Cheap and squishy. Good for blocking drafts but fails quickly when wet. Often included with the AC. | | Closed-Cell Foam Tape | ⭐⭐⭐⭐ | Denser and more durable than open-cell. Better for compression seals and water resistance. Highly recommended. | | Rubber Weatherstripping | ⭐⭐⭐⭐ | Excellent for large gaps. Durable and long-lasting, but can be visible. | | Silicone Caulk | ⭐⭐⭐⭐⭐ | The gold standard for waterproofing, but use sparingly if you intend to remove the unit seasonally. | | Duct Tape | ⭐ | Avoid. It leaves a sticky residue, peels off in the heat, and looks unsightly. Use foil tape instead. |
Sealing your window air conditioner is the most important step for maintaining a cool home and a low electric bill. A poorly sealed unit allows frosty air to escape while inviting humid heat, allergens, and insects inside. how to seal window air conditioner
| Scenario | Best Material | | --- | --- | | Renter / Seasonal | Removable rope caulk + foam tape | | Permanent installation | Silicone caulk (outside) + rigid foam board (top) | | High wind area | Backer rod in accordion folds + aluminum foil tape | | Very old, uneven windows | V-strip (tension seal) which bridges large gaps | | Material | Rating | Review | |
Sealing a window air conditioner is essential for maintaining energy efficiency, blocking drafts, and preventing pests from entering your home. Whether you are setting it up for summer or winterizing it to stay in the window year-round, following a structured approach ensures a tight, professional seal. | | Closed-Cell Foam Tape | ⭐⭐⭐⭐ |
Buy a "Side Panel Insulation Kit." These are thick foam boards that you cut to size and stick over the flimsy plastic accordion panels. Step 4: Seal with Weatherstrip Tape