Reliabilt-window-mull-kit-instructions May 2026

: 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.

: 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

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

: You can find series-specific PDFs (e.g., Series 105 or 150) on the ReliaBilt Installation Support page . This step is critical for preventing air and water leaks

Mulling is the process of joining two or more windows together to fit into a single large opening. If you are using a , the process involves preparing the frames, applying sealant, and securing the units with structural connectors. ReliaBilt Window Mull Kit Installation Steps

: Open the window sashes to access the factory pre-drilled holes or specific reinforcement areas. Drive the provided screws through one frame into the other (staggering them if necessary) to pull the units tightly together.

: 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.