Approved Document B addresses fire safety precautions which must be adhered to, to ensure the safety of occupants, firefighters and those close to the building in the event of a fire. (for use in England) 
The document covers all standards related to this, including means of escape, the ability to internally isolate a blaze to prevent a fire from spreading, external fire spread, firefighter access to the building and facilities, fire detection and warning systems in place within a building.
It also addresses the internal spread of a fire due to the structure or lining used within a building and safety measures related to this.  
 
Document B is separated into two volumes, this volume covers dwellings. 
 
Both volumes address the same issues, but the information has been adapted for each type of structure, for example different guidance on escape routes depending on building type. 
 
Main changes made by the 2020
amendments
The changes focus on the following fire safety provisions in blocks of flats:
a. Sprinklers:
A reduction in the trigger height from 30m to 11m.
b. Wayfinding signage for the fire service:
A new recommendation for floor identification and flat indication signage within blocks of flats
with storeys over 11m.
In addition a typographical error is corrected in both volumes. Purpose group number 2 is now
included in reference to ‘residential’ buildings in the guidance on boundaries.
The changes are set out in the May 2020 AD B amendments.