Building Regulations Part M set out specific requirments for principle communal entrance doors including dwellings.
Minium clear opening width
In accordance with the recommendations set out in Approved Document M, the principle communal entrance doors of buildings containing dwellings should have minium clear opening of 775mm.
The clear opening should be measured in accordance with image below:
a: Inside Face of the door
b: Inside edge of the door frame
c: Leading edge
d: Following edge
The clear width is measured between the doorstop and the face of the open door;
Principle communal entrance door’s threshold should be an accessible threshold. Accessible threshold is a type of threshold at the doorway which should have a maximum 15mm up-stand.