What Types of Fire Retardant Sealant Are There?

Fire safety is a major concern in the construction of modern buildings. However, most fires, whether related to short circuits or any other sources, are avoidable when controlled earlier.Proper sealing is one of the best ways you can control the spread of fire and smoke. Fire retardant sealant is a life-saving barrier, which fills gaps, seals joints and penetrations, to make walls, floors and ceilings fire-resistant.

However, not all sealants are fire retardant. So, choose the one that is most suitable for your intended application. Different fire-rated sealants are used according to the application areas, like on tubes, ducts, or structural joints.

In this article, we will talk about some of the most common types of fire-rated sealants and discuss their application.So, let's get started.

What Is a Fire Retardant Sealant?

A fire retardant sealant is also commercially known as a fire‑stop or fire-rated sealant. It is a specially formulated material used to seal small joints, gaps, or openings, around pipes, cables, ducts, walls and floors. In case of fire, it helps prevent fire and smoke from spreading between compartments.

These sealants have fire resistance ratings typically ranging from 30 minutes up to 4 hours and are categorized as passive fire protection products. Their fire resistance ratings will depend on the product and specified construction standards. Unlike ordinary caulks/sealants, fire-resistant ones expand or react with heat, helping to stop the transmission of fire. These products are quite essential in improving the overall fire-resistance ratings in walls, floors and ceilings.

Up to 80% of fire-related deaths result from inhaling smoke, not burns. This emphasizes the importance of right fire rated sealants for compartmental sealing.

Main Types of Fire-Retardant Sealant

There are five common types of fire-retardant sealants, each of them is applicable in different situations:

Intumescent sealants

These sealants expand significantly when exposed to high temperatures, forming a dense char to seal penetrations and block flames and smoke. They are commonly used around plastic conduits or pipes in fire-rated walls and floors. Intumescent sealants have different formulations (silicon, acrylic or polyurethane based) and are suitable for up to 4‑hour fire ratings.

Acrylic (non‑intumescent) firestop sealants

These sealants are mostly water-based and have low VOC content. These are typically paintable, and are a perfect solution for sealing small penetrations in dry indoor environments. These do not expand under heat and offer basic fire retardant capability. You will need to compliment them with a separate intumescent system for higher fire ratings.

Silicone firestop sealants

These are known for their high temperature resistance, excellent flexibility, and durability in exterior or high-moisture environments. Silicone sealants may not be intumesce, but they maintain sealing performance under heavy joint movement and wet conditions. Most silicon firestop sealants have W‑rating for water repellence.

Hybrid / Elastomeric sealants

These hybrid sealands combine silicone-like flexibility with strong adhesion typical of polyurethane. They offer enhanced performance where both movement and fire resistance are required. They are ideal for dynamic or mixed-substrate joints.

Cementitious / Mortar‑based firestop compounds

These are rigid sealants, such as firestop mortar, and are designed for large structural voids or through-penetrations where movement is minimal. They are commonly used in heavy-duty applications, like walls, ducts, or load-bearing openings.

All these types serve different applications, but they have one common goal, and that is to stop the fire from spreading.

Comparing Different Sealants

Let’s see how these different types of fire-rated sealants compare, to find out the most suitable one for your application. 

The type of sealant you choose largely depends on your intended use, budget and atmosphere (indoor or outdoor). So, access your budget and application requirements before you choose the right sealant.

Common Applications in Building Design

Fire-retardant sealant plays a key role in many areas of modern construction. Their effective application does not only improve safety but also complies with the strict fire code and insurance regulations.

Some of the common applications include:

Sealing service penetrations in fire-rated walls and floors

Fire-rated sealants are applied around penetrations, such as pipes, electrical conduits, ducts, cables. This helps prevent flames and smoke from passing through fire-rated assemblies.

Joint sealing in construction seams

These sealants are used in gaps between wall or floor slabs, control joints, and expansion joints to maintain compartmentalization and slow down fire and smoke transfer.

Perimeter joints around doors, windows, and frames

Sealants fill gaps around door and window frames to preserve fire-resistance ratings and safeguard escape routes.

Fire-rated facade joints and curtain-wall systems

Specialized fire-retardant sealants (mostly silicone-based) are used for facade expansion, perimeter, and glazing joints to maintain fire integrity while allowing movement and weather sealing.

Cable tray and electrical equipment sealing

They are applied in power facilities, large buildings (like hospitals, hotels, airports) to seal tray and cable openings and to comply with compartmentation requirements.

High-rise and multi-story building shaft firestopping

Fire retardant sealants are utilised in shafts and vertical voids (like service risers, stairwells, duct penetrations) to control flue effects and preserve fire separation between floors.

Many commercial contractors report using fire-retardant foam sealant as a routine part of passive fire protection in new construction projects.

Key Considerations When Choosing a Fire-Retardant Sealant

Fire retardants are far more than just a compliance requirement; they offer long-term safety for both buildings and people. When so much is on the line, you can not just select any other sealant and expect it to stop fire spread. Following are some of the things to consider before you choose a fire-rated sealant:

● Fire Rating Requirements: The fire rating of the product (1-hour, 2-hour) should be in line with the safety code or building code.

● Material Compatibility: The sealant must be compatible with concrete, metal, gypsum or plastic surfaces.

● Movement Tolerance: In the case of moving joints or structures, select a sealant that can handle the movement. Most silicon based sealants can handle aggressive movements.

● Installation Ease: consider a sealant that provides a perfect balance of ease-of-use and fire rating. This  is important for large-scale jobs.

Moreover, ensure that it is UL-classified or ASTM-tested to verify its fire resistance.

Final Thoughts

Fire rated sealants provide passive protection, sealing gaps in the walls, sealings and floors to stop fire spread. They have become an important part of modern buildings as they are easy to use, are compatible with the existing building materials and help with compartmentalization of buildings. However, don't choose any fire retardant sealant; do your research, compare their types and choose the one that is most suitable for the job on hand.