Today, buildings are constructed using a greater variety of materials, including masonry, timber, steel, metallic, and polymeric materials—all of which expand at different rates in a fire. Some degrade quickly, while others distort. When construction materials “move” in a fire situation, gaps are opened and shapes and sizes of penetrations change, which in turn, allow fire and smoke to pass through. In these situations, traditional firestop materials simply do not work well, as they do not respond to the changes taking place. In comparison, intumescent products react and expand to fill all the gaps and changes created by the fire, and therefore, can maintain a high-performance fire barrier for an extended duration. The key requirement of a good firestopping product is one which will fill, insulate, and seal all gaps in a building fire compartment as a fire develops and movement occurs.
Another reason for building movement is due to seismic activity. This often happens over time, before a fire occurs, and can cause gaps and cavities in the fire compartment to appear and grow in size. Traditional firestopping methods cannot usually seal such changes in construction, or they become dislodged or damaged, so the fire compartment is compromised long before any fire-related events. Intumescent firestopping products have been tested and shown to fill any large gaps and cavities present before a fire occurs.
A further benefit of intumescent products is their installation, which is generally simpler. Traditional firestops tend to require a great deal of skill and time to install correctly, as they often require combinations of both wet and dry processes. Intumescent products tend to be designed for the specific application, and the skilled parts of the product are incorporated at the factory in controlled conditions and not onsite.
Types of intumescent products
While it is a widely accepted opinion that intumescent products represent much safer solutions for many firestopping applications, it is not the whole story. All intumescent products are not created equally. Today’s products can be divided into two basic groups: dumb and smart intumescent materials.
Dumb intumescent materials
A dumb intumescent is typically a rubber-based material which is extruded or pressed into sheets, with no structure to the dispersion of the intumescent particles within the application. The main reason it is called “dumb” is because when it expands, it has no sense of direction and will expand in all directions equally. In addition, if a random gap exists, it will flow through it as well, rather than in the direction required to stop the fire spread.
While I agree that there are a variety of intumescent materials, I was sharply disappointed that there is no mention of firestop SYSTEMS in the article. Given the widespread lack of understanding about firestopping in the AEC industry, it is too easy for someone to read this article and think, “Oh, I need to get some “smart” intumescent material for my project.” without recognizing that the IBC requires firestop systems (2021 sections 714.4.1.2 for penetrations and 715.3 for joints). The materials, intumescent or not, must be installed in strict conformance to a UL Certified firestop system or an Engineering Judgment from a firestop manufacturer. No matter what materials are used, it is not just up to the installers to decide what material(s) to use and how to install them. Unless the firestop materials are installed in conformance to an approved firestop system, there is no confidence that openings and joints will be properly protected and will provide their part in the compartmentation needed in a structure fire.