What mullion means
A mullion is the vertical or horizontal bar between two window units or panes that are joined together, carrying part of the structure.
Where it matters on a window and door job
Mulled units ship joined at the factory or are joined on site, and the mull joint is a common leak point. Seal and flash it as carefully as the window perimeter.
What it costs
Koira's bay window installation cost guide puts a typical job at $2,500, with most between $970 to $5,650. The guide shows its sources and what moves the price. The window replacement cost calculator prices a job line by line.
Work it out
- Free calculator: Window replacement cost calculator
- Cost guide: Bay window installation cost
- Tools, templates and guides: Free window and door resources