Sealing Aluminum Window Joints

Set an extension ladder or stepladder under the window to reach the aluminum window.

Scrape old caulking material off the window joint between the frame and siding with a scraper.

Spray a rag or sponge with an all-purpose cleaner.

Wipe the aluminum window joints with the rag to remove the dirt and debris from the exterior of the window. Use a stiff nylon brush to scrub away stubborn dirt and debris. Dry the window joints with a dry rag.

Put a tube of exterior-grade silicone caulk into a caulking gun. Cut the tip of the tube with a utility knife. Pierce the tube's inner seal with a sharp nail.

Align the tip of the caulking tube with the window joint, beginning at the edge of the window joint.

Squeeze the caulking gun's trigger to express the silicone caulk. Move the tip of the caulking tube along the joint to lay an even bead of 1/8- to 1/4-inch silicone caulk in one line along the window joint.

Dip a plastic spoon, popsicle stick or a finger in water. Place the spoon, popsicle stick or finger at the beginning of the caulk bead, press down and move it along to force the silicone caulk into the joint and smooth the surface. Repeat the process for each window joint.

Open the window to access the bottom of the window sash, which is a movable joint. Spray a rag or sponge with an all-purpose cleaner and wipe the bottom of the window sash.

Measure the bottom of the window sash from end to end with a tape measure. Note the measurement.

Stretch out a section of self-adhesive tubular gasket weather stripping on a cutting surface.

Measure the gasket weather stripping to match the window sash measurement. Mark the gasket with a marker or chalk.

Cut the tubular gasket along the marker or chalk line with a utility knife.

Peel a 3- to 4-inch section of the protective film off the back of the gasket. Align the edge of the gasket with the edge of the window sash and press the gasket in place. Peel off the protective film in 3- to 4-inch sections and adhere it to the bottom of the window sash. Continue to peel the protective film and stick it onto the sash until the tubular gasket covers the sash.

Pull the upper window sash down if it is movable and apply a tubular gasket to the top of the upper sash using the same method as for the bottom of the window sash. Repeat for each window.