Intumescent sealant, also known as fire mastic, adds an extra layer of passive fire protection to a building to slow the spread of fire and smoke.
It is designed to reinforce the fire resistance of walls, floors, and door frames by sealing unprotected cavities such as linear joints and pipe penetrations.
Intumescent sealants expand in volume when exposed to extreme heat, filling voids to form a tight seal, which prevents fires and smoke from spreading.
The use of intumescent sealant is becoming increasingly popular as fire regulations become more stringent, since they are a versatile solution that can help protect a building's structural integrity as well as reduce smoke-related casualties.
In this blog post we will explore what intumescent sealant is, the benefits, and how to use it for your project.
What is intumescent sealant?
Intumescent sealant is a firm yet flexible product that is typically made of a silicone or water-based acrylic containing graphite.
When exposed to extreme heat, the graphite material within the sealant expands to form a char, restricting smoke and fire passage.
The sealant slows down the speed at which the burning process takes place by providing up to 240 minutes of fire resistance (depending on the product certificate), which then helps to protect the structure it is applied to, stopping the fire from spreading to other areas.
What are the benefits of using intumescent sealant?
Intumescent sealant can be a simple, yet effective element of a passive fire protection system, when applied correctly. It has a range of benefits and can be used for multiple applications in many different environments.
The benefits:
- Can provide up to 240 minutes fire resistance
- Excellent adhesion with most common building materials
- For use where rigid seals are impractical
- Smoke tight
- Provides effective acoustic containment
- Quick and easy to install
- Can be painted over
- Cost effective
How to use intumescent sealant
Intumescent sealants can be used in many different ways, however not all products are suitable for all applications.
Check the data sheet of the manufacturer to determine which intumescent sealant is most suitable for your project.
Where to use intumescent sealant?
The use of intumescent sealant is ideal for sealing linear joints and voids in door frames, floors, fire walls, and other applications, with minimal effort.
It can also be used in conjunction with other fire stopping measures such as fire batts, pipe collars, and air transfer grilles where structures have been penetrated by these services, filling any voids that have been created.
Intumescent sealants are specially formulated to provide good adhesion with a wide range of materials including wood, masonry, and plasterboard.
How to apply intumescent sealant
- For internal applications ensure that all the surfaces are clean, dry and dust free. Clean all joints thoroughly to ensure good adhesion.
- It may be necessary to mask adjacent areas to prevent contamination and protect the surrounding area. Masking tapes should be immediately removed after tooling and finishing.
- Attach the sealant cartridge or foil sausage to an applicator gun.
- Install backing materials if required and slowly fill the cavity or around the service penetration with the sealant to the required amount.
- The joint should be tooled or smoothed over within 5 minutes of application to ensure good contact between the acrylic and substrate, giving a smooth and professional finish.
- Allow sealant to dry and dispose of used cartridges in line with local regulations.
- Clean all tools and application equipment with water immediately after use.
- Once dry it can be painted over if required.
How We Can Help
We stock a range of trusted intumescent sealants from well-known manufacturers such as Rockwool, FSi, and Nullifire, available in singular tubes, foils and bulk packs.
If you need advice regarding intumescent sealant, or other passive fire protection queries, contact our technical team on 02920 857 959 or [email protected], and we will be happy to assist you.
