What is the minimum horizontal firewall projection according to PD 1096?

The minimum horizontal firewall projection according to PD 1096 is specified as 600 mm. This requirement enhances the effectiveness of firewalls in preventing the horizontal spread of fire between adjacent buildings or spaces. The 600 mm projection serves to create a safer separation, allowing for an adequate overhang that can help to divert flames and reduce the risk of fire transmission.

In the context of building safety regulations, such specifications are critical for ensuring that fire-resistance measures are sufficiently robust. The rationale behind having a defined measurement like 600 mm is to establish a standard that can be applied consistently across various constructions, thereby promoting uniform safety standards in fire prevention.

Other numbers given in the choices do not meet the established standards outlined in PD 1096, which is why they wouldn't be the correct answer.