Skip to main content

Seal Exterior of Window — Install Remaining Flashing and Sealant

Beginner2 mins

Part of project

Window Installation · Step 7 of 8

Helpful?

In this video

Once the window is securely fastened, move to the exterior to seal the perimeter. Using a caulking gun, apply a continuous bead of exterior-grade sealant around the sides and top of the window frame where it meets the house siding or trim. It is crucial to leave the bottom edge of the window frame unsealed, as this provides a weep hole for any water that might get behind the window to drain out, preventing rot and water damage.

55.5K views157

FAQs

What are the most important safety precautions to take during window installation?

Always wear safety glasses and gloves to protect against debris, sharp edges, and sealant. If working above the ground floor, use appropriate ladders or scaffolding safely. Be sure to have help to lift and position the window, as they can be heavy and awkward, preventing injury or damage.

Beyond the listed tools, what other essential supplies might a beginner need for a successful and weatherproof window installation?

You will definitely need shims (wood or plastic) to properly level and plumb the window within the rough opening. A utility knife with extra blades for cutting flashing tape, and a caulking gun for applying sealant are also crucial for a clean, professional finish.

What are common mistakes beginners make when flashing and sealing a new window that could lead to leaks?

A common mistake is not applying flashing tape in the correct shingle-fashion, which can trap water. Another is using too little sealant or not ensuring a continuous bead, leaving gaps for water intrusion. Always overlap flashing layers from bottom to top and apply sealant generously to critical areas.

Is a 2-day estimated time realistic for a beginner installing a window, and what factors could extend it?

The 2-day estimate can be realistic for a beginner with a standard-sized window and a clean rough opening. However, unexpected issues like discovering rot in the rough opening, dealing with an out-of-square frame, or struggling with the weight of the window can easily extend the project time.