How to Install Aluminum Window Mullion
Adding an aluminum window mullion structure to a rough window opening allows you to group multiple windows next to one another in a single rough opening. The mullion structure can accommodate several windows of smaller size and lower cost to give the same light stream, air circulation and glass exposure as much-larger, more-costly standard or custom windows. Does this Spark an idea?
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Things You'll Need
- Mullion strips and mounting hardware
- Drill
- Wood or stucco screws
- Measuring tape
- Level
- Windows
- Silicone caulking
Instructions
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1
Measure for the placement of each mullion based on the width of each window in as many intervals as you are mounting windows. Lay down the bracket onto the rough opening sill and mark the screw holes with a pencil, repeating this for the top and bottom brackets.
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2
Drill two screws into each of the top and bottom brackets. Use screws suited to the substrate material. If it is a wood sill, use wood screws; if stucco, use masonry screws for the most durable connection.
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3
Slide the aluminum mullion assembly, without the decorative mullion cover, into the brackets. Check for level and secure with screws at both the top and bottom ends of the mullion and on each side of each bracket.
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4
Install the windows according to their manufacturer's specifications and secure their nailing fins. Check for level and plumb. Caulk around the windows and down the center of the mullion bar or in keeping with the particular manufacturer's specifications. Allow the silicone caulking to dry to the touch.
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5
Slide or snap the decorative mullion cover or covers into place to cap the entire mullion assembly and proceed with trimming out the finished windows.
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