What is the requirement for fireblocking in two-family dwellings?

In two-family dwellings, the requirement for fireblocking is essential to prevent the spread of fire and smoke between different areas of the building. Fireblocking is specifically mandated in concealed spaces, such as walls or floors that are not readily accessible. These areas can allow flames and hot gases to move quickly between units, which increases the danger during a fire incident.

The International Residential Code mandates fireblocking to be installed at specific points in the structure, including areas where there are changes in floor levels, around ducts, and in places where there are vertical spaces. By having fireblocking in these concealed spaces, it effectively creates barriers that limit the passage of fire and smoke, thus enhancing the overall safety of the building and its occupants.

The other options do not align with the requirements set forth by the code. For example, limiting fireblocking to just door openings or roof assemblies does not address the critical areas that need protection, and stating that it is not required at all does not adhere to safety regulations established for residential buildings. Therefore, understanding the necessity of fireblocking in concealed spaces directly supports the goal of minimizing fire risks in two-family dwellings.