Mullion (Door)

Related terms

• Muntin / Grille

  The narrow bars dividing a window into smaller panes (true divided lite) or simulating that look (grilles between or on the glass).

• Mullion

  A structural vertical (or horizontal) member dividing or joining adjacent window units.

• Nailing Flange / Fin

  An integral perimeter fin on new-construction windows fastened to the sheathing and integrated with flashing for a weather-tight install.

• Mortise Lock

  A heavy-duty lock body recessed into a pocket cut in the door edge, more durable and secure than a tubular bored lock. Common on premium…

• New-Construction Window

  A window with a nailing flange for installation before siding goes on, used in new builds and full-frame replacements with siding removed.

• Low-E Coating

  A microscopically thin metallic coating on glass that reflects radiant heat while passing light, sharply improving energy performance.

• NFRC Label

  The National Fenestration Rating Council label that reports U-factor, SHGC, VT, and air leakage so windows can be compared on a common ba…

• Lite

  A glass panel within a door (e.g., 'half-lite', 'full-lite', or decorative entry lites).