Spray applied fireproofing can be sprayed onto steel to insulate it from the heat of a fire, thus saving lives by providing enough time for people to get out of the building. The material can be cement based or fiber based since both materials have UL testing to ensure safety. Sprayed fireproofing can be used for various materials like wood, fabric, structural steel and more. They do this by thermally insulating the structural members to keep them below the temperatures that cause failure.
It has been known for nearly a hundred years that structural steel fails quickly when heated by fire. A short time later, building codes began to require protection of the structural steel in fire-resistive buildings, and rated the levels of protection as it did fire division walls (one-hour, two-hour, and so on).
The earliest forms of protection were to encase the steel columns and beams in terra-cotta (baked clay tile), concrete, or masonry. Later, gypsum plaster applied to wire lath was used, to reduce the weight of the fire protection. Multiple layers of gypsum drywall board were also used to reduce the labor required for installation. This method is still in use today.
When applying a fireproof coating to structures, it is vital for the material to dry within a specific amount of time. While some fireproofing sprays contain chemical accelerators to speed hardening, they still produce a significant amount of moisture during the application process. Incidentally, the fire-resistant material may be more difficult to dry than drywall or cement. Without the right ambient conditions or construction drying services, a contractor may face delays and unintentionally create safety risks.
Sprayed Fireproofing Process
The specific characteristics of each material, the manner in which they are prepared and applied all affect the fire-resistive qualities of SFRM material. One of the most critical elements for a properly installed SFRM is its applied thickness. Sufficient insulation is available to mitigate the passage of heat from a fire to the structure being protected only if proper SFRM thickness is ensured.
The installed-SFRM must at least provide the level of thermal protection equivalent to that provided for the test assembly-during the standard test. There are various standards set and performance tests carried out for the fireproofing materials.
The industry has categorized SFRMs as either “Wet Spray” or “Dry Spray” materials so that the terms better describe the manner in which the material is mixed, conveyed and applied.
Use of Spray Applied Fireproofing
Spray applied fireproofing is primarily used to protect rigid structural elements including columns, beams, metal decking, and some steel joists from the effects of heat generated during a fire.
While not its primary use, SFRM may also provide acoustical treatment and thermal insulation for large areas where the structural members and metal decking are left exposed, but treated with SFRM. This should be thought of as an added benefit since there are other materials specifically made for providing acoustical or thermal insulation.
Spray applied fireproofing IS NOT suitable for surfaces exposed to moisture or high humidity levels. The moisture and humidity will deteriorate the products. In addition, the moisture may cause mold growth due to the porous nature of SFRM.
How to Apply
SFRM is typically sprayed on using a Wet Spray or Dry Spray system in accordance with NFCA100.
Wet spray SFRMs are combined with water to form a slurry that is passed through a hose and dispersed with air through a nozzle. This procedure can improve installation time by 10 -15% per day.
Dry Spray SFRMs are conditioned through application equipment and then pneumatically passed through a hose to the nozzle where atomized water is introduced. Spray is then directed at the substrate and applied in an even uninterrupted pattern. Dry spray systems are useful if application occurs during severe weather conditions.
An alternate method of applying SFRM is by troweling the material onto required areas. This is recommended to be done following a spraying operation in each area to complete the SFRM coverage. The troweling method is also used to patch damaged or otherwise loose areas.
Heating and ventilation may be needed for curing. SFRM is susceptible to damage during the curing period so precautions to protect it should be taken. Ducts, piping, equipment, metal stud framing, and suspended material shall only be positioned after the SFRM has been fully cured.
In areas where SFRM has been removed, it should be repaired by a manufacturer approved and licensed contractor or NFCA Accredited Contractor. It is important to use the same or compatible material to maintain the approved UL design and fire resistance rating of the affected building.
Fireproofing is often installed immediately after the structure has been set, but before the various MEP systems have been put in place. Installation of pipes and ductwork usually require beam clamps, which requires fireproofing to be chipped away. Therefore, it is important that the contractor returns to patch the SFRM installation.
SFRMs generally require no maintenance, however property owners should periodically inspect fireproofed areas to ensure that applied SFRM material hasn’t been damaged. If it is found to be loose, cracked, or damaged it should be repaired immediately.