Off-site steel fire rating – What you need to know

Off-site steel fire rating – What you need to know

If you are a regular reader of our blogs, or work in the fire-rating industry, you know by now that one of the most effective passive fire protection measures for structural steel is the application of thin-film intumescent coatings. This product category has multiple advantages over solvent based products and even more over older technologies, or even concrete encasement, not least of all the fact that they can be applied either on-site or off-site (The advantages over alternatives is something we have discussed on numerous occasions, but check out some of our other blogs if you would like a refresher).

In the past, we have discussed the choices between on and off-site application, but wanted to look at it again, helping you to better understand what you need to know about the growing trend of off-site/modular construction and the factors driving it. In today’s blog, we wanted to take a deeper look at when you may use off-site application of fire rating measures, and the reasons not to use anything but thin film intumescent coatings for off-site applications.

What are off-site/modular constructions?

When a structure is built off-site (away from the location it will eventually come to be located) under controlled plant conditions, it is termed modular construction. But really, it is a fancy phrase for the construction of key elements away from the site. The processes are slightly different for construction, however, the process utilises similar materials, adheres to the same codes and requires the same sign off as conventional construction. Structures are produced in “modules” that are then transported and assembled on site. The elements constructed under this process have become almost indistinguishable from those built on-site so good is the standard these days.

Today, the demand for modular construction has dramatically increased as more and more construction companies and clients discover the benefits. In fact, modular construction is estimated to be valued at $196.2 billion by 2026 globally, which just shows its growth, utilisation, and increasing preference by builders all over the world.

Above and beyond the above growth statistics, let’s take a top-level look at some of the advantages of off-site construction:

It is greener

Because it is factory-controlled, the process produces less waste, creates less site disruptions in operations, and allows for tighter construction timelines.

Greater Flexibility and Reuse. It is very straightforward to disassemble modular buildings in the warehouse and relocate, or even remove from one site and refurbish for new use elsewhere. This leads to the reduction of demand for raw materials and limits the energy expended to create a structure to meet a new need.

Less Material Waste:  Waste of materials is reduced significantly through recycling, controlling inventory and protecting building materials when production is in a factory. Less site wastage, reduced theft of products from site etc all mean less products are used.

Improved Quality:  The fact that the elements are built in a controlled environment means that the temperature can be controlled, the humidity and moisture can be controlled more too, meaning overall, the quality of the produced components is of the highest quality.


Allows for faster construction

Modular construction happens simultaneously with work occurring on site, allowing builders accelerate timelines and achieve cost savings in construction, as it decreases typical construction time.

Reduced Construction Schedule: Because construction of modular buildings can occur with simultaneous on-site construction, projects can be completed faster, with some reports citing speed improvements of up to 30 percent.

Elimination of Weather Delays: Since most of the construction is completed inside a factory, there is less risk of project delays associated with bad weather. This ensures that project completion is achieved on time, leading to a faster return on investment.

Built to Code with Quality Materials: Modular buildings are built to meet or exceed the same building codes and standards as site-built structures. As a result, the same architect-specified materials used in conventionally constructed buildings are used in modular construction projects—wood, concrete and steel.


Smarter Solution

As a result of being constructed with the same materials, building codes and architectural specifications as on-site builds, once assembled, modular buildings are virtually indistinguishable from site-built structures.
Safer Construction:  There is reduced accident risk liability for workers on site as off-site construction usually happens indoor in factory environments where strict occupational safety protocols can be enforced.

Better Engineered Building: Modular construction relies on advanced visualisation to assess the energy performance and identify the most cost-effective efficiency measures. As it uses technology to improve engineering outcomes, the end product often offers better performance long-term than it may otherwise.

Limitless Design Opportunities: Modular units can be designed to fit any shape and aesthetics giving them a wide array of design and architectural flexibility.


Off-site application of thin film intumescent coatings

With the advantages afforded through off-site construction, we have received numerous questions regarding the application of fire rated materials to steel members. As we advise people asking this, there is only one product type which is suitable – thin film intumescents.

An Intumescent coating is a layer of defensive substance which works by chemical reaction when exposed to heat—by swelling and insulating through forming a layer on the surface. Normally sprayed-on, they give the thickness needed as per a predefined fire resistance. Intumescent coating thickness varies depending on the fire resistance period required and the steel section size.

Made from solvent or water-based materials, they are a cost-effective and practical answer for fire and corrosion protection and coverage of structures made of composites and steel (though there are a range of new products for protection of timber too). Intumescent coatings can be applied off-site so that the steelwork arrives with fire protection previously applied on-site. The advantage is that the application is done offsite, again speeding up construction timelines and removing complications that many arise from the organisation of multiple trades on site.

For many years, Vermiculite has been used as a spray-on intumescent for steel. A naturally occurring silicate material that expands when exposed to heat, vermiculite exhibits a scope of properties that make it appropriate for fire security. Excellent at insulation, it’s additionally non-combustible, retentive, compressible, odourless and inert.

But, while it is a good material for passive fire protection, Vermiculite is shockingly susceptible to damage as it absorbs moisture easily and is easily damaged through contact. This can lead to cracking, compromising the structure and the adequacy of its overall fire protection. As a result, application of vermiculite off-site is not recommended as it:

  1. May be damaged in transport
  2. May get wet during transport
  3. Will be very heavy to transport regardless of moisture

Suffice to say, this technology has scarcely changed through the years and is basically seen as an outdated option.

Fireboards, on the other hand, are fire resistant boards made for construction where proper insulation is required. Lightweight, they are utilised to store and redistribute the heat and are perfect both as a construction and insulation material. However, they are susceptible to damage during transportation, a factor that greatly affects their use in modular construction processes.

As a result, we thoroughly recommend that it is high time to move on to suitable alternative applications for thin film intumescent coatings off-site. This is where thin film intumescent coatings such as Nullifire SC902 come in handy when applying fire rating protection off-site.

Nullifire SC902

Nullifire SC902 is intumescent coating technology that offers unparalleled versatility and performance in coating application and fire protection of structural steel. This innovative technology was been engineered to provide effective solutions for the challenges associated with both off-site and on site application and provide a good alternative to existing thin film paints and board systems.

It offers all the presentation advantages of thick film 90 and 120 minute water-based intumescent coatings but with the unique benefit of rapid cure technology. This provides the added advantage of more efficient construction timelines. As a finished substance, it is hard in nature yet has an impressive level of adaptability, giving it great mechanical impact resistance. Furthermore, it is also highly tolerant to varying conditions; resistant to storage/construction; and in the event of damage, is easily repaired.  This makes Nullifire SC902 the perfect choice for off-site application and transportation for modular construction. If you are looking to using SC902 for your off-site construction needs, we are here to assist you. Just let us know.

Get in Touch

Speak to the leaders in passive fire protection

You are about to download a file from the Permax site. Please note All technical advisory notes generated by Permax are based on research papers, indicative fire tests and any other existing evidence. These documents should not be used as an official evidence as design engineers should review the information and determine the reliability of the documents.

Permax constantly update the documentations based on the new fire testing outcomes and change of standards and regulations. To ensure the documents you read are up-to-date, please contact the Permax technical team.