What material must be used to fireblock all spaces between chimneys and floors or ceilings?

To properly fireblock all spaces between chimneys and floors or ceilings, noncombustible material must be used. This requirement is essential for fire safety in buildings, as noncombustible materials can effectively prevent the spread of fire and contain it within specific areas. The use of noncombustible material ensures that any heat or flames generated by the chimney do not ignite surrounding structures or materials, maintaining the integrity of fire-rated assemblies.

In building codes, fireblocking is a critical component in minimizing fire hazards. Noncombustible materials, such as concrete, brick, or certain types of gypsum board, are designed to withstand high temperatures without contributing to the combustion process, which helps to protect occupants and property.

The other materials mentioned—wood, combustible materials, and insulation—do not fulfill this requirement due to their potential to ignite and spread fire, which can create significant risks in case of a fire incident. As a result, their use in areas needing fireblocking around chimneys is not compliant with fire safety standards.