Reliabilt-window-mull-kit-instructions

: Lay the windows side-by-side on a flat surface. Use a utility knife to trim any excess vinyl "welds" or protruding edges from the corners where the windows will meet to ensure a flush fit.

: Run a continuous bead of 100% silicone sealant along the entire length of the channel where the windows will connect. This step is critical for preventing air and water leaks. reliabilt-window-mull-kit-instructions

: You can find series-specific PDFs (e.g., Series 105 or 150) on the ReliaBilt Installation Support page . : Lay the windows side-by-side on a flat surface

: Align the windows and press the mullion strip (the H-shaped or snap-on piece from your kit) into the channel. You may need a rubber mallet to gently tap the strip into place until it snaps securely. This step is critical for preventing air and water leaks

: If your windows have nailing fins or J-channels on the sides being mulled, remove them using pliers or a utility knife to allow the frames to sit tightly together.

: For a visual walkthrough, check out this guide on How to Mull Two Vinyl Windows Together . Window mullion installation #Lowes