Intumescent Coating or Cementitious Coating: Which Offers Better Steel Fireproofing?

Posted on 12th November 2019

Structural steel can only retain about 50 percent of its strength when exposed to extreme temperatures and so protecting Structural Steel with Fireproofing is essential. In the event of a fire, with temperatures reaching around 600 degrees Celsius, structural failure is virtually inevitable and the chance of a building made with structural steel collapsing is much higher.

It is no wonder that the Building Code requires builders to implement effective measures to help protect buildings and its occupants for as long as possible in the event of a fire.

As far as Passive Fire Protection, two key options are used: Intumescent Coating and Cementitious Coating. If you require the former option, NSW Spray Coatings Specialist offers an exceptional Intumescent Paint Sydney service with highly trained professionals. Although both effective in their own ways, one option simply wins out over the other and offers Better Steel Fireproofing.

Intumescent Coating

Intumescent Coating is a popular form of Fire Rated Spray Coating and is easy to apply, effective and also a highly economical option. Intumescent Paints or Intumescent Sealants are made from materials which can expand and swell due to heat exposure. This swelling (also called charring) decreases in density and significantly slows down the structural steel’s heating and thus prevent its collapse. Unlike Cementitious Coating, it can be applied with one layer but can also use additional layers when required.


  • Comparatively easier for trained painters; a significant amount of structural steel fire resistance can be achieved with a single layer
  • Low Labour Costs
  • Saves on-site costs lower due to fast application and ease-of-use
  • Works well in wet or moist conditions. It doesn’t absorb moisture and thus prevents corrosion even during severe water flow
  • Low amount of overspray
  • Low maintenance is required due to a strong bond even without a finish coat


  • May not be ideal for areas where impact damage is high

Cementitious Coating

Cementitious Coating, also known as lightweight cementitious, is made from vermiculite, perlite or other lightweight aggregates and then combined with heat-absorbing material such as Portland cement. Foaming agents or other additives are also added and mixed together in order to reinforce its strength. It needs to be layered continuously to achieve the required Fire Resistance level and is applied directly to the structure.


  • Prime for Dry Environments
  • Resistance to High Temperatures
  • An Affordable Solution


  • Labour costs are higher because more fieldwork is required due to many layers of the coating needing to be applied successively.
  • Cementitious Coating is prone to cracking, disintegration or spalling when exposed to vibrations or heavy impacts
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  • Adds a significant amount of weight to the overall structure. This may increase costs due to more structural steel required to handle the weight.
  • Not ideal for places with a lot of moisture because it can cause gaps between the structural steel/substrate and the coating.

In Conclusion

Although both Cementitious Coatings and Intumescent Coatings are effective Passive Fireproofing options, Intumescent Fireproofing simply reigns supreme as far as cost-effectiveness, time saving, ease and versatility of application and most importantly fireproofing effectiveness.

To receive the best Intumescent Coatings applied by the industry’s top experts, contact NSWSCS today at 1800 825 258.