: Apply additional silicone sealant to the top and bottom of the mull joint, filling any voids. If your kit includes a drip cap or mull bridge , install and seal these over the top and bottom exterior joints. Helpful Resources
: 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. reliabilt-window-mull-kit-instructions
: 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. : Apply additional silicone sealant to the top
: 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. Drive the provided screws through one frame into
: You can find series-specific PDFs (e.g., Series 105 or 150) on the ReliaBilt Installation Support page .
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