This is because extra core component materials are required in the construction of the door to achieve its fire rating.
Fire door size chart.
Local codes should be reviewed but in general rated doors must be self closing and must have a positive latch.
Just add 2 to the width of the actual door size.
You should add 2 1 2 to the height of the actual door.
Common options are 2040 x 526 626 726 826 926 x 40mm.
Fire door standard sizes.
Chart of door ratings and labels.
Getting the rough opening size right the first time will save you from frustration when installing your doors.
Framing rough opening sizes are really quite simple.
This will give you room to space the door frame off of the sub floor.
20 gage door constructions are approved for smaller door sizes than what is shown above.
There are also limits to the size of glazing in the door the width of gaps between door panels the height of the door under cut and the size of air transfer grilles.
Fire ratings for doors are influenced by but not limited to the following items.
Metric size fire doors are also available within some of the ranges and there is usually the option of the following sizes to select from 626mm x 2040mm 726mm x 2040mm 626mm x 2040mm and 926mm x 2040mm it is worth noting that although these are standard metric sizes not all doors will be available in these sizes whilst metric size doors.
Door size conversion chart.
Maximum doors size for fire ratings is influenced by but not limited to the following items.
Metric sized internal doors are becoming increasingly popular and are now commonly used in scotland and europe.