Fire Retardant Coatings – A Comparison

01 Sep 2022 by Permax

Fire retardants are nothing new in construction. Since the ‘70s fire retardant coatings and materials such as Vermiculite have been used on buildings to protect the steel from fire. With an appearance similar to paper mache everyone has likely seen this type of protective coating in car parks, or even older sporting arenas.

With the advances of technology, however, newer alternatives are available including thin-film intumescents. And whilst we will be the first to admit that Vermiculite will always have a place (for non exposed areas), when it comes to architectural finishes, thin-film coatings cannot be beaten.

So what are the differences of thin film options (sometimes incorrectly called intumescent fireproofing paint)? This blog aims to find out.

Why It Is Time To Move On From Vermiculite

Vermiculite is a product that has been around for more than 30 years now. One of the reasons why it became a popular fire retardant is because it often comes in spray form, which is easy to apply to structures. Plus, it is affordable in terms of cost per meter. However, this technology has barely changed over the years and is essentially outdated. Further, as mentioned above, when it comes to exposed steel (which is the way building trends have gone), vermiculite is an eye-sore as it cannot be top coated and it takes up a lot of space.

Further, whilst it may be quicker to apply vermiculite, the time to dry is much longer, and the risk of damage, much higher, meaning the initial savings may be quickly eroded.

Compared to current intumescent fire retardant coating technologies, Vermiculate spraying means waiting for it to dry. This will restrict builders’ access to certain floors which will affect the construction timeline. And while it is a good material to passively protect a building from fire, Vermiculite is surprisingly susceptible to damage.

In fact, it can easily be corroded by water. Since it easily absorbs moisture, Vermiculite can end up cracking, thus compromising the integrity of the structure and the effectiveness of a building’s overall fire protection. That makes it unsuitable for use on exterior parts of a building, perimeter structures, and other areas exposed to inclement weather.

On top of all that, Vermiculite can negatively impact a building design’s aesthetics. Many architects and engineers don’t like to specify it as it can be downright ugly. Since Vermiculite is a thick material, it can limit construction clearances, which leads to the reduction of available open space. The thickness also adds more weight to the structure, which needs to be carefully managed otherwise a building’s stability and integrity can be compromised.

What are we saying you ask? Basically, it is high time to move on to better fire-retardant coating alternatives. This is where intumescent fire retardant paint comes into the picture.

Intumescent Fireproofing Paint – Why Switch To Them?

Intumescents are the latest in fire protection technology – yet they are far from “new”. There are several options out there, but generally, they are composed of a primer, basecoat, and sealer coat. They contain substances that produce non-flammable gasses when coming into contact with fire, inhibiting the spread of flames. They also swell into thick padding (called a char), which will provide insulation and protection from a conflagration.

As mentioned, there are various options for intumescent fireproofing paint out there that can meet different fire resistance requirements. Whether a building is required to meet the 30, 60, or 90 minutes fire resistance requirement, intumescents can potentially be used. In fact, recent developments have made available coatings that can withstand fire for up to 120 minutes. This can really help minimise the damage just in case it takes longer to control a fire accident.

Thin Film Intumescents Are The Way Forward

It makes sense to employ the latest and more effective fire retardant technologies on today’s construction projects. Thin film intumescent fireproofing paint is especially a great option. Here are the main reasons why:

Thin Film Is Thin And Light

As its name suggests, thin film intumescent fire-retardant coating provides a thinner finish compared to Vermiculite. This makes it a light material to add to the structure and its effects on a building’s stress points, overall stability and integrity are highly manageable. It is also great for use in tighter spaces and won’t reduce available spaces much.

As already mentioned above, thin film does well – up to 7x its original thickness when coming into contact with fire. It is designed to protect underlying structure, which thus mitigates the malevolence and spread of a fire.If nothing else, this makes it a highly effective and reliable intumescent fire retardant paint.

More Design And Aesthetics

Freedom – Outdoor Use

Since it is light, thin film intumescent paint provides architects with more versatility to design more aesthetically pleasing structures. Plus fire rated Intumescents for concrete, timber and steel are all available

Intumescent paint for steel is the most commonly used option given the prevalence of steel in construction still, though with the rise of timber products for construction, this balance will change. But in saying that it will change to more Intumescents for timber and less vermiculite overall.

It Dries Faster

You don’t have to wait for too long for thin film to dry. It can be top-coated as well. So, whilst it can be more expensive to apply you will be able to save on the man-hours required to fireproof a building. Plus, other construction timelines will only be affected minimally – if at all.

Thin Film Can Be Applied Offsite

The fact that thin film intumescent fireproofing paint can be applied offsite makes it an even better fire protection choice. Any parts or steel that needs to be coated can be processed at a different location while more work can continue on the main construction time.

After the paint coating is done offsite, the finished parts can be transported and installed into the building without fuss. And as intumescents such as Nullifire are resilient and harder to damage, the risks in moving the steel is minimized. Again, this provides more flexibility in how a building is designed and constructed.

That also means that the mess and disruption on the main construction site are reduced. Basically, using thin film is great not only for fire protection but also for productivity.


When it comes to fireproofing a structure, Vermiculite may be a cost-effective option at first glance but a thin film intumescent fire retardant coating is a far better option.

It is more effective, it provides design flexibility, and will improve the flow of the overall construction process.

Permax only source and supply products from the best manufacturers from around the world – those whose products meet the most stringent of criteria.The Permax team are highly qualified to help you with any question you may have. We can develop specifications, provide technical advisory notes and offer advice on design details to suit your project.We are Permax: a team of knowledgeable and experienced professionals who work with our clients to determine the right specifications for their project, determine ways to optimise the quantities required and ensure you are supported throughout the engineering and application process.Whether you are looking to learn more about the Nullifire range of products, source materials or a local certified installer, or are looking for technical assistance, Permax are here to help you.At Permax we are happy to offer our assistance and advice for your structural steel fire protection requirements. Our industry expertise has led us to compile a collection of the questions we are most frequently asked. One of our popular brand of structural steel fire protection is Nullifire.Nullifire is a brand recognized as a global leader in passive fire protection systems, and has become synonymous with some of the best structural steel fire protection coatings technologies available today. Formulated and manufactured to the highest standards, the Nullifire thin film intumescent coatings – specifically the SC900 series - offer application and performance advantages which have made it the first choice of builders, engineers, architects and specifiers in many countries world wide.Combating The Effects Of Fire - WIth NullifireFires are generally classified as either Cellulosic or Hydrocarbon fires. The essential difference between them relates to how quickly each reaches its maximum temperature range and the combustible fuel source feeding the fire.Cellulosic fires are those that are fuelled by materials such as timber, furniture, paper, plastics and other common items as found in buildings such as offices, hospitals, shopping centres and residential buildings.In such a fire, temperatures quickly reach around 550 degrees Celsius which over the course of the fire will have a dramatic effect on the structural steel within the building. Whilst it will not burn, it will warp and lose its ability to support a load, increasing the likelihood of building collapse.Under the NCC all buildings with exposed structural steel are required to implement protective measures around the steel.The Nullifire range of intumescent coatings are designed to protect structural steel in the case of cellulosic fire. Often called fire retardants, or mistakenly called "fireproof" paints, intumescent coatings refer to that class of specially formulated coatings which swell and form a protective "char" as a result of extreme heat exposure.Nullifire intumescent basecoats are formulated specifically to fire protect structural steel up to a fire rating level of 120 minutes.


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