What is the minimum distance that a firewall must extend beyond the edge of a building?

A firewall is a crucial building element designed to prevent the spread of fire between two separate structures or within different sections of the same building. The requirement for a firewall to extend beyond the edge of a building is established in building codes to ensure adequate protection and minimize the risks associated with fire spread.

In this case, the correct choice specifies that the minimum distance a firewall must extend beyond the edge of a building is 300 mm. This 300 mm extension provides a safe buffer that helps to reduce the likelihood of flames from an adjacent burning structure affecting the integrity of the building's wall.

Regulations typically take into account factors such as the potential for fire, the construction materials used, and the proximity of other buildings when determining these distances. Extending the firewall by this specified distance ensures that the wall can effectively protect against heat radiation and direct flame contact.

The other distances mentioned in the other options may not meet the recommended guidelines established by applicable building codes or fire safety standards, which emphasize the importance of adequate protection in preventing fire from spreading beyond its point of origin.