August 14, 2023 | Feature Article

NEW FM APPROVAL STANDARD FOR FIRE RESISTANT ASSEMBLIES

First FM Approved coating to improve wood roof decks from Class 2 to Class 1

Passive fire protection is critical in achieving fire compartmentation, a strategy that results in the division of buildings into smaller subsections that slow and contain the spread of fire and smoke. This allows time for evacuation, time for fire services to arrive, and can help reduce losses. Passive fire protection is used in concert with active fire protection systems such as smoke and fire detectors, sprinkler systems, emergency lighting, foam or gas suppression systems, and smoke ventilation.

Global Intumescent Coatings Market Pie Chart

Fig 1 -- Construction and the oil and gas industries lead the list of the largest users of intumescent coatings on a global basis, according to a study by Grand View Research.

According to a recent study, the global market for intumescent coatings was estimated at USD 1.14 billion last year (fig 1) and projected to grow at a rate of 5.3 percent per year from 2023 to 2030. Intumescent coatings are fire resistant products that are applied in a thin layer like paint yet can provide protection against fire by expanding (up to 100x its original thickness) to form an insulating char when exposed to high temperatures.

Fire Triangle

Fig 2 -- The fire triangle requires an ongoing supply of oxygen, heat, and fuel to generate and maintain a fire. Fire resistant coatings, such as Firefree 88® from Firefree Coatings, Inc., help disrupt the fire triangle and prevent or reduce the risk of fire, smoke, and heat development.

The Fire Triangle (fig 2) illustrates the three elements a fire needs to ignite and be maintained: an ongoing supply of oxygen, heat, and fuel. Fire resistant coatings, such as Firefree 88® from Firefree Coatings, Inc., help disrupt the fire triangle and prevent or reduce the risk of fire, smoke, and heat development. 

Intumescent coatings can provide cost-effective fire protection for many structures, including steel beams, wood roof decks, walls, floor joists, concrete surfaces. These coatings are one type of passive fire protection, which may also include fire resistant windows and doors, fire stopping, and the use of fire resistant building materials.

New application tested

Recently, FM Approvals certified a water-based intumescent coating from Firefree Coatings, Inc., based in Novato, California, USA. The thin-film coating, known as Firefree 88® Coating, was tested in the FM Approvals' Construction Materials Calorimeter (fig 3) in West Glocester, Rhode Island, and certified as the first-ever FM Approved coating that can be used to upgrade Class 2 wood roof deck assemblies to Class 1 rating. Up to now, all FM Approved coatings were limited to steel roof decks.

Diagram of Calorimeter

Fig 3 -- Diagram of FM Approvals Construction Products Calorimeter used to evaluate wood roof deck samples coated on the underside with Firefree 88® intumescent coating. The samples were tested in accordance with the fire test protocols detailed in FM Standard 4470, Single-Ply, Polymer-Modified Bitumen Sheet, Build-Up Roof (BUR) and Liquid Applied Roof Assemblies for Use in Class 1 and Noncombustible Roof Deck Construction.

Firefree 88 first achieved FM Approval almost 20 years ago when it met the requirements of FM 4975, Fire-Retardant Paints and Coatings Over Combustible Surfaces. Introduced in 2000, Firefree 88 has been tested to multiple standards worldwide and can be used to provide the fire-rated performance required by the International Building Code (IBC) for some wall assemblies, floor/ceiling assemblies and individual structural members.

Due to its environmentally friendly water-based formula, Firefree 88 is listed in the FM Approval Guide as a Green product. The new FM Approvals certification for Firefree 88 was conducted in accordance with FM 4470, Single-Ply, Polymer-Modified bitumen Sheet, Built-up Roof and Liquid Applied Roof Assemblies for Use in Class 1 and Noncombustible Roof Deck Construction.

"While our recent testing of Firefree 88 was on wood roof deck assemblies, this coating can be used on roof decks of wood or steel,” notes Joanna Blaney, assistant vice president and technical team manager for the FM Approvals materials group. “For instance, you may have a steel roof deck with an asphalt layer mopped directly on to it, which could self-propagate if exposed to fire from below. This coating could mitigate that risk as well."

Cost-effective solution

According to Timothee Rodrique, assistant vice president and staff engineering specialist for FM Global, the availability of an FM Approved intumescent coating that can cost-effectively upgrade the fire rating of roof assemblies without major renovations or downtime is a significant benefit.

"We can now recommend this FM Approved coating for existing and new locations," Rodrique notes. "As opposed to more costly improvements or solutions that may increase the load on a structure, Firefree 88 intumescent coating can be spray applied providing a cost-effective and time savings improvement. In fact, soon after Firefree 88 was certified for this purpose, we received a question from one of our account engineers about a wood roof deck asking what could be done about it. We were able to refer him to this product—it was a timely certification."

Firefree Coatings was founded in 2000, based on the success of Firefree 88 and other fire resistant technologies. Firefree 88 is used in residential, commercial, and municipal projects, both for new and renovation projects.

According to Firefree Coatings president Elisa Vivas, Firefree 88 intumescent coating can provide a true fire barrier to a wide variety of materials and assemblies. "Our users really appreciate the fact that Firefree 88 looks like paint and provides a much better finish appearance than other alternatives such as cementitious coatings,” Vivas explains. “It can also be covered with tinted standard latex paint, which will not impact the performance."

She continues, "We have been working with FM Approvals for nearly 20 years. Our latest program began a few years ago but was delayed during the pandemic. We value our partnership with FM Approvals. The FM diamond opens doors for us on a global basis. One of the greatest benefits of our relationship with FM Approvals is that the program helps us provide consistent quality control. We are always testing our raw materials to meet our own standards and as part of the surveillance audits required by FM Approvals. We are proud of the fact that we’re the first to meet the FM Approvals standard under FM 4470 for the protection of wood roof assemblies." 

According to FM Approvals senior engineer Joe Nunes, who managed the Firefree 88 testing program, "This latest test program for Firefree 88 provides a new FM Approved solution for retrofit roof assemblies. A one-millimeter dried film thickness (DFT) undercoating of Firefree 88 (fig 4 and 5) provides a fire resistant layer for roof assemblies that can boost fire performance cost-effectively and quickly. This was an important program because it provides an FM Approved solution where none existed before."

Pre-burn Sample

Fig 4 -- This sample wood roof deck has been coated with a nominal 40 mil (1 mm) dried film thickness (DFT) layer of Firefree 88® intumescent fire-resistant coating. The sample is ready to be tested in accordance with FM 4470.

Post-burn Sample

Fig 5 -- After testing. The wood roof deck assembly chars – but does not burn – during fire tests in the FM Approvals’ Construction Materials Calorimeter. The Firefree 88® intumescent coating is a water-based paint that swells when heated, forming a beneficial char that insulates and protects.