On-site Vs. Off-site

The Nullifire SC902 ‘hybrid’ intumescent coating system based on patented technology that delivers exceptional productivity gains for both on-site-vs-off-site-intumescent application. This is in comparison with conventional intumescent coatings used for structural steel fire protection.


On-site application

Due to tight construction timelines, access or logistical considerations, it is not always viable to apply intumescent coatings to steel off-site. In these situations, intumescent applicators will allow for appropriate time and masking of surrounding areas in order to ensure there is minimal disruption to the construction sequence. Depending on the construction program required the intumescent application can also be broken into stages. Following are advantages and disadvantages of On-Site application:


Advantages (conventional intumescent coatings)

  • Generally, does not require the use of large or complex spray application equipment, which is very advantageous when dealing with difficult or restricted access on-site.
  • All steel work to be intumescent coated is already erected and in place, which significantly reduces the likelihood of damages occurring as can be the case when off-site painted steel is transported to the construction site, off loaded and erected.
  • Application of intumescent coating is not a ‘wet trade’ so does not delay construction activities waiting for access to floors.

Advantages of Nullifire SC902 on-site

  • Nullifire SC902 has a low VOC thus has minimal impact on construction sites.
  • Nullifire SC902 is a rapid curing coating and achieves early weather resistance within 1 hour of application, which is ideal for open construction sites.
  • Nullifire SC902 is very surface tolerant of high humidity (85% RH) or low temperatures (cures down to 0˚C).
  • Nullifire SC902 has an ultra-high film build due to it’s 85% volume solids formulation, which allows the coating to be sprayed in a single application, saving time on-site and delivers speedy access to floors for following trades.
  • Nullifire SC902 is easily repaired with minimal surface preparation, using simple application equipment.


  • May require specific protection of areas adjacent to structures being sprayed on-site to avoid overspray contamination.
  • May not be suitable if installed steelwork does not allow sufficient access to all surfaces that require intumescent spray application.


Off-site application

Applying an intumescent off-site can save time in the construction schedule as it means trades are not required to spend days moving between floors and applying intumescent on site. After the steel is erected, there is a shorter period which applicators are required to be on-site in order to patch any damages or spray steel connections. Following are advantages and disadvantages of Off-Site application:



  • Avoids delays in accessing work sites due to construction program delays, continuous inclement weather conditions or other trades occupying floor areas for extended periods of time.
  • Reduces the number of trades on-site.
  • Removes fire protection application from the critical path of the construction program.
  • Improves application productivity as time is not taken up with moving equipment, product and personnel from various areas or floor levels.
  • Provides better control of application conditions due to the ability to control environmental conditions such as temperature and humidity, which can prove to be difficult when dealing with open construction sites.
  • Generally stricter control of QA processes which leads to a higher quality application.

Advantages of Nullifire SC902 off-site

  • Can be applied directly to blasted steel without the need of a primer, for internal or semi-exposed environments.
  • Surface tolerant of light rusting and can be applied up to 2 weeks post blasting, allowing greater flexibility for the painting program.
  • Has a 60% faster application and curing time than conventional intumescent coatings, including epoxies, allowing coated steel to be handled and transported the next day.
  • Optimizes productivity through the paint shop due to high film build capabilities allowing a single application process to achieve all fire rating levels. Quicker delivery of coated steel saves on labour costs and construction delays.
  • Very easily sanded for treatment of difficult to spray configurations requiring a high level of finish.


  • Solvent based intumescent coatings are not as hard as fully cured epoxy intumescent coatings so more care needs to be taken with handling in the paint shop and also transport loading/securing considerations to avoid excessive damage.
  • When coated steel arrives at the construction site, additional care needs to be taken with regards to lifting and erection processes to avoid excessive damage.
  • Bolted connections need to be dealt with on-site which may cause delays for other trades when these have to be intumescent coated.

These are pros and cons of on-site Vs. off-site intumescent application.

The intumescent bolt caps available at Permax can also be used on projects which mean that connections are not required to be sprayed on-site. Instead bolt holes are masked during application off-site and once the steel is erected, bolt caps are attached to either end of bolts to achieve the required fire rating.



Learn more about Permax and our download one of our technical resources.

Disclaimer: Permax is a supplier of various fire protection products that are manufactured in global locations. The Permax advisory notes are developed to assist the professions in the Australian construction industry with their passive fire protection design. If you are unsure about the content of the documents or if you have any project specific enquiries, please contact the Permax Technical Team for further assistance.

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.