What is a key characteristic of cementitious fireproofing coatings?

A key characteristic of cementitious fireproofing coatings is that they are often lightweight and can be applied in thick layers to achieve the desired fire protection levels. These coatings typically consist of cement, aggregates, and additives that contribute to their bulk and texture. The ability to apply them in thicker layers is important as it enhances their insulating properties, providing effective thermal protection for structural elements exposed to fire.

The lightweight nature allows for ease of application and reduces the overall load on the structure. This is particularly beneficial in construction projects where maintaining the structural integrity and load capacity is crucial. Hence, the association of cementitious coatings with both lightweight properties and the application of thicker layers serves to optimize fire safety measures.

In contrast, some of the other options do not align with the principal characteristics of cementitious fireproofing. For example, while cementitious coatings may show some swelling upon heat exposure, this is not a defining characteristic, as swelling is generally more associated with other types of fireproofing materials. Additionally, cementitious materials do not typically require thin layers for adherence; thicker applications are more effective. Finally, these coatings are not made from synthetic rubber; rather, they are fundamentally based on cement, making the materials distinctly different.