French Door Fire Rating Options Masonite Architectural Wood Doors believe in the importance of flexibility, allowing you to choose the door you want. The charts below set out our minimum dimensions for our French doors as well as the maximum dimensions that will secure a UL- or Warnock Hersey-sponsored fire rating. In addition, we can usually construct doors that surpass the dimensions listed below and give them Construction Label Only (CLO) tags. Masonite Architectural Wood Doors has set the standard in fire-rated French doors. Our 20-minute doors feature our unique all-wood true divided lite construction. This means that each lite is an individual piece of glass framed by pieces of wood instead of one large piece of glass with a wooden "grate" sitting on each side of the glass. The true divided lite construction has many advantages, but the primary reason people choose it is for its high quality finished look. All standard sticking options and lited elevations are available in 20-minute fire-ratings. See 20-Minute Fire-rated Glazing Options Dimension Ranges (Neutral Pressure) Dimensions Non-Rated 20-Minute Max door height 10' 9' Max door width 4' 4' Max door thickness 2 1/4" 2 1/4" Min door thickness 1 3/8" 1 3/4" Min stile height 9" 9" Min stile width 3" 5" Min mullion width 3" 3" Min rail length 9" 9" Min top rail width 3" 5" Min cross/lock rail width 3" 3" Min bottom rail width 3" 9 1/2" Min bar/munt width 1/2" 1" Min bar/munt width 1 3/8" 1 3/4" Minimum height and width are dependant on minimum dimensions of door components and will vary between elevations Dimension Ranges (Positive Pressure) Dimensions 20-Minute Max door height 9' Max door width 4' Min door thickness 1 3/4"