INTRODUCTION
In October 2017, a series of destructive wildfires spread across Northern California. The Tubbs Fire — a wildfire so named due to its point of origin near Tubbs Lane, Calistoga — resulted in the deaths of 22 people and the destruction of more than 5,643 buildings across Lake, Napa and Sonoma counties. In Redwood Valley, California, Bob Gates watched as the Mendocino Lake Complex wildfire incinerated every house in his neighborhood including his own home. No structure was left standing except for a standalone home office on Gates’s property which endured in part due to the resilience enabled by its fiber cement cladding from Nichiha. In this white paper, we discuss how fiber cement can increase the resilience of homes and other structures in the face of environmental threats posed by sun, precipitation, wildlife, wind and fire. Following the section on fire resilience, we return to the story of Bob Gates and the Redwood Valley Mendocino Lake Complex Fire. In a separate case study, we present the experience of a major drugstore chain and how fiber cement enables brand consistency and compliance with standards for hurricane resistance.
PHYSICAL PROPERTIES
Fiber cement consists of fibrous materials such as wood pulp mixed with Portland cement, water and silica or fly ash. By virtue of its physical properties, fiber cement siding is less susceptible to common environmental threats than traditional wood cladding. For example, in coastal areas, natural wood is vulnerable to airborne salt water that may accelerate deterioration. Elsewhere, wood siding may be compromised with rot caused by common fungi. Given that fiber cement is at least 70 percent inorganic, neither of these environmental features significantly impact fiber cement’s longevity or appearance. This increased durability does not require any aesthetic sacrifices. Available as boards and architectural wall panels, fiber cement is highly-versatile and can be processed and pressed to create products of varying sizes, lengths, thicknesses and textures. Fiber cement can be molded to closely resemble natural products,such as wood and stone, or fashioned to foster a clean, ultra-modern look. Unlike vinyl, both wood and fiber cement can be painted. To retain its appearance, wood siding typically needs to be repainted every three to five years. Fiber cement can retain its painted appearance for 12 years or more. Some fiber cement manufacturers offer 15-year warranties on decorative factory finishes and colors.
INCREASED DURABILITY DOES NOT REQUIRE ANY AESTHETIC SACRIFICES.
While reading the sections to follow, remember that the performance of fiber cement is in part contingent upon proper installation. Manufacturers provide detailed guides for homeowners, small businesses and contractors describing clearances, flashing, placement of joints, proper tools and other requirements. For major brands and companies, some fiber cement manufacturers provide dedicated resources to ensure successful installations, brand consistency and comprehensive technical support.
SUN AND HEAT
Of particular relevance to areas that experience significant heat and fluctuations in temperature, fiber cement siding resists the impacts of thermal expansion. Heat increases the movement of matter’s constituent atoms and molecules; as the particles move they occupy more space. As a result, matter expands. Cold has an opposite effect as it causes atoms to move less and occupy less space. Cold causes matter to contract. The rates at which different substances expand and contract vary by the strength of the forces that bond their atoms. Fiber cement is a more stable material than wood — it has stronger bonds between its constituent atoms — and will not experience contraction and expansion at the same rate, at the same temperature. Under conditions where wood siding cracks and chips as a result of expansion and contraction, fiber cement experiences minimal change.
STRONGER. MORE STABLE. LESS CONTRACTION & EXPANSION.
In California, heat and thermal expansion pose a regular threat to the longevity of cladding materials. Inland, it is not uncommon to experience 30 days of very dry, very hot days where temperatures reach 100 degrees Fahrenheit or more. In other areas — such as in the Central Valley — temperatures swing from hot during the day to cold at night. While fiber cement has a slower rate of expansion than wood, fiber cement panel systems should be installed with appropriate expansion joint regimes — some manufacturers recommend placing an expansion joint every 30 feet. With this hardware behind the panels, fiber cement is kept from shifting out of place in the case of any expansion and contraction. This is particularly important on south- and west-facing exposures due to the amount of sunlight. As a best practice, toward the end of its finishing warranty, fiber cement panels should be repainted, or in the case of prefinished wall panels, refreshed with new clear coating. This will ensure continued aesthetic appeal and resistance to ultraviolet radiation.
PRECIPITATION AND MOISTURE
Modern fiber cement is impact-resistant compared to vinyl and wood siding and well-suited to resist the impacts of falling hail, snow and rain. Fiber cement panel systems have a strong record in terms of resisting water penetration even under harsh torrential rain. Some panel systems are equipped with a ceiling gasket to prevent infiltration of water and air on the top and right edges of each panel. With shiplap edges, the panels fit together so that joints are concealed and all four edges effectively get a ceiling gasket. The ASTM E 331 test method measures the resistance of manufactured assemblies to water penetration when water is applied with uniform static air pressure at the outdoor surface greater than the pressure at the indoor face. This simulates the impact of wind-driven rain. Similarly, the AAMA 509-9 test method for rainscreens measures the resistance of fiber cement to winddriven rain, but it also collects moisture that gets beyond the panels to the weather barrier behind the panel system. Through these tests, manufacturers have proven fiber cement’s ability to resist water penetration
when properly installed; in the rainscreen tests, no moisture was able to get through the system even with simulated wind and water striking the panels at roughly 75 miles per hour and pressures of 12 to 16 pounds per square foot (PSF).
Manufacturers take additional precautions by including drainage channels between the sheathing face and the back face of the panels. These drainage channels and the additional weep holes built into the system’s hardware ensure that any water that manages to penetrate the panel system will drain out. Fiber cement products that do not require a rainscreen are also unlikely to trap moisture even in the case of water intrusion. These products are directly applied on the sheathing surface as overlapping horizontal clapboards, which easily shed moisture and should also have flashing installed over each joint to divert water. Just as manufacturers take precautions to ensure the performance of fiber
cement in the face of rain, homeowners and businesses can follow best practices recommended in manufacturer installation guides such as maintaining weather barriers as a backup for moisture drainage systems and installing kick-out-flashings that will divert rain that is running down from the roof away from the face of walls. In the case of snow accumulation, the thickness and flexural strength of fiber cement enables it to withstand the physical force exerted by snow piles leaning against a structure. Residential-grade fiber cement is made with a wet process that mixes water with the fibrous material, silica and Portland cement. This means residential-grade fiber cement has some sensitivity to thaw and pre-thaw conditions in cold climates. Dry process fiber cement, which is not made with water, is not vulnerable in this respect and may be more appropriate for areas with cold climates such as Illinois, Minnesota, North Dakota and Wisconsin. As mentioned earlier, many fiber cement manufacturers offer 15-year finishing warranties on pre-finished products. Refinishing toward the end of the warranty period extends the life of the product by allowing the 30 percent or less of fibrous material in fiber cement to get wet and then dry without damaging the siding’s appearance. In addition, as a hygroscopic material, wood expands as it absorbs airborne moisture and contracts as it dries. Thus, humidity — the amount of water vapor in the air — is another element of the environment that will impact wood but not fiber cement to the same degree.
WILDLIFE
While conducting interviews for this white paper, we encountered a homeowner whose property had been damaged by woodpeckers. Unfortunately for the homeowner, the woodpeckers were considered an endangered species in his area and his options for dealing with them were limited (e.g. no pellet guns). After the woodpeckers damaged his home’s wooden trim, the owner installed fiber cement trim as a replacement. Like termites and other woodland pests, woodpeckers are not able to do much with fiber cement. The birds remained but ceased to be a proble
WIND
Fiber cement’s capacity for wind resistance varies by product and by installation. Commercial-grade fiber cement panels are engineered to withstand high wind loads and may be installed with highperformance hardware that allows for concealed fastening of panels. To meet the challenge of unusually high wind loads, commercial panel framing can be upgraded to 16-gauge metal from 18-gauge metal; this will strengthen the hold of the panel’s fasteners. Some manufacturers also offer steel hardware instead of the usual aluminum. Homeowners who reside in regions frequently subject to hurricanes or high wind gusts may want to consider selecting a commercial panel system as opposed to residential shiplap. If homeowners decide to install fiber cement as lap siding, they can achieve increased resistance to wind by attaching siding with roofing nails instead of siding nails or fastening siding with screws. Above all else, for best performance, adhere to local building codes and manufacturer guidelines. As High-Velocity Hurricane Zones (HVHZ), Florida’s Miami-Dade and Broward Counties have established strict building codes to ensure structures are designed and constructed to resist the potentially severe wind loads in their regions. HVHZ requirements are rigorous and architects everywhere look to these counties when specifying for structures that must be especially resilient to storms. For use in an HVHZ, some manufacturers offer commercial-grade panel systems and concealed hardware able to withstand pressures of 80 PSF, which would indicate
a severe wind event. New clips are expected to increase the resistance of commercial-grade panel systems to 95 PSF in the near future. Miami-Dade County maintains a checklist for fiber cement products that are approved for use in an HVHZ. This checklist includes detailed product and installation information and current test results and reports. Under the Florida building code, approved products are required to pass the following tests conducted by a laboratory in compliance with the International Code Council’s Testing Application Standard (TAS) 301:
• Testing for standard specifications per ASTM C-1185
• Smoke density rating and flame spread test per ASTM E-84
• Test method for behavior of material in a vertical tube furnace per ASTM E-136
• Uniform static air test per TAS 202
• Impact test per TAS 201 (not required for soffit)
• Cyclic test per TAS 203
• Wind-driven rain test per TAS 100 (A) for vented soffits only
Fiber cement siding installed in front of concrete block construction that satisfies the ASTM C90 for load-bearing concrete does not require impact and positive pressure tests for HVHZ approval. The same is true for fiber cement installed in front of 5/8 inches (5-Ply) plywood supported by 16-inch o.c. 2x wood or metal framing. Still, some fiber cement manufacturers have conducted impact testing to measure how fiber cement would perform in a hurricane. Tests may include trying to find a weak or unsupported point of a panel by blasting a two-by-four from a 90-degree angle perpendicular to it at 60 miles per hour. Preliminary results for some fiber cement products indicate that the centers will hold and deflect.
When a major drugstore chain attended the 2012 BuildPoint®, a retail construction and architecture conference, they were looking to revamp the design of their new locations – in particular, they needed to replace their current Exterior Insulation and Finish System (EIFS) products with a more adaptable building exterior. Opening hundreds of new stores every year, the drugstore chain required a product that would fit its brand’s aesthetic, fulfill local jurisdiction criteria and could be scaled for a reasonable cost. After speaking with a representative at BuildPoint, the company decided Nichiha offered the right product for the company and signed on to Nichiha’s Retail Partner Program. Through national brand partnerships, Nichiha provides major brands with building prototypes, access to its full line of cladding products, a personal coordinator that oversees the entire planning and installation process, as well as comprehensive technical support. The drugstore chain now uses Nichiha cladding as part of its typical design. In addition to easier jurisdiction approval, the chain has found that their partnership with Nichiha is helping the company save money and put up new locations in a timely manner. “By going to this more contemporary look, we didn’t add any cost to our construction, [or] increase our construction time frame,” said the drugstore chain’s architecture and engineering department manager.
“We are seeing a decrease in the cost of the building as compared to previous buildings built before the 2016 timeframe. As general contractors get used to the exterior material, it’s going up fairly quickly. I also haven’t heard of a single install having too many issues on utilizing the Nichiha product.” The manager also commented on how Nichiha panels enabled the drugstore chain to maintain its architectural aesthetic while satisfying rigorous Miami-Dade requirements for wind resilience. “I have always been a fan of Nichiha, and it has opened up many possibilities for new stores. We previously have used High Impact EIFS to meet Miami-Dade County wind requirements — many exterior panel manufacturers do not have approved FBC or NOA approvals— but it limited the architectural quality of the building. Though Florida is one of the few areas where EIFS is readily accepted by the jurisdictions, it meant having a disjointed architectural aesthetic compared to the rest of the country. Nichiha allows all of our stores to look both contemporary and provide a reliable exterior skin that is flexible when a jurisdiction asks for material or color changes.”
FIRE In an encounter with fire, wood siding quickly becomes fuel and vinyl siding will melt. Fiber cement siding — which consists mostly of non-flammable cement and silica — will resist combustion. Organizations such as the American Society for Testing Materials (ASTM), the National Fire Protection Association (NFPA) and the Canada/Unlimited Liability Corporation (CAN/ULC) have developed an array of tests that manufacturers and governments use to measure ignition resistance, combustibility, and flame spread in building/wall products. Such tests include:
• ASTM E 84: Standard test method for determining surface burning characteristics such as flame spread and smoke development of building materials
• CAN/ULC S102-10: Standard test method for determining surface burning characteristics of building materials and assemblies
• CAN/ULC-S134-13: Standard test method for determining the comparative burning characteristics of exterior wall assemblies
• NFPA 268: Standard test method for determining ignitibility of exterior wall assemblies using a radiant heat energy source
• NFPA 285: Standard test method for determining the suitability of exterior wall assemblies and panels on buildings where exterior walls are required to be non-combustible
As a result of these tests, manufacturers are able to prove that fiber cement may be safely used with wall assemblies that organizations such as NFPA have rated as fire-resistant. Manufacturers have also demonstrated which fiber cement products have a Flame Spread Index of zero and qualify as Class A building materials under ASTM E 84. Fiber cement’s proven capacity for resisting fire is particularly relevant to those who live and work in California, Colorado, Idaho, Ohio, Montana, Nevada, Wyoming and other areas at high-risk for wildfires. In Chapter 7A of its building code, California — which is a trendsetter when it comes to codes and construction — established standards and guidelines for materials and construction methods that help buildings increase fire resilience and the survivability of people and property located in areas designated as Fire Hazard Severity Zones or Wildland-Urban Interface Fire Areas (WUI). Fiber cement products have been tested and approved for use in WUI areas and can help protect buildings from ignition by embers that can fly as far as a mile away from a wildfire. California’s Office of the State Fire Marshal (SFM) — which oversees WUI codes — manages the Building Materials Listing (BML) Program that lists tested and approved products — including fiber cement — that are in compliance with Chapter 7A of the California building code. To be listed in the BML, all products must be tested and labeled by an SFMaccredited laboratory. Fiber cement is assessed under Testing Standard CA SFM 12.7A-1, Exterior Wall Siding and Sheathing. While using tools like California’s BML to choose compliant products will increase overall fire resistance, fiber cement will not make a home or business invulnerable to fire. What fiber cement provides is another layer of protection for people and property. To achieve the best results in terms of fire resistance, it is still necessary to follow best practices such as keeping at least six inches of clearance between siding and combustible items such as plants or mulch. Manufacturers and local governments can provide useful guidance in this area and suggest how to best create defensible spaces.
Roughly 10 years ago, Linda and Bob Gates of Redwood Valley, California built a standalone home office on their five-acre property for Linda’s successful art therapy practice. The 1,400-square-foot office stood 175 feet away from the 2,000-squarefoot house they built in 1992. Flanked by vineyards to the west and north, their primary home was custom-built with a marble entryway, solid fir doors, hardwood floors, tropical hardwood in their bedrooms and redwood siding. Their property also included a 3,000-square-foot deck made of redwood. The Gates family selected Nichiha Sierra Shake siding for the home office because it would match their house and give them the look of redwood without requiring significant maintenance. Sierra Shake siding is pre-finished with a machine-applied coating engineered to provide long-lasting color, enhanced durability and a consistent appearance. Bob said, “The Nichiha product came painted and it looked like redwood shingles. The depth and thickness allowed it to be grooved. It looks like we put it up there yesterday. And I come from a painter’s family. That really cuts the cost, if you think about it. One step and done.” On October 9, 2017, with the howls of 50 to 60 mile per hour gusts disturbing them all night, Linda and Bob had difficulty sleeping. Bob decided to get up. “I woke up and looked out of our windows — which faced to the north and the south — and through the ones to the north, I could see that all of the ridges were on fire. It had to be a three- to-four-mile fire from ridge to ridge.” Starting in early October 2017, Northern California experienced a series of 250 wildfires that came to be known as the Northern California Firestorm. Twentyone of these wildfires developed into major wildfires including the Tubbs Fire, which ultimately proved to be the most destructive wildfire in California’s history. Located within Mendocino County, the small community of Redwood Valley and its 2,300 residents were in the path of the Redwood Valley Mendocino Lake Complex Fire, which killed eight people, burned 36,523 acres and destroyed 546 structures before it was contained. Unaware of the scale of the fire, Bob walked outside around 3:00 am with the intention of fortifying the property against the incoming flames. “I had originally thought we could fight it, but there is no way to really fight this. You can’t expose yourself to this kind of fire. It will just kill you. It will burn all the hair off your arms, even if it doesn’t feel that hot when it’s blowing. I was lucky. We lost plenty of people. The children who were lost here, we knew. The older people who were lost here, I knew, personally.”
There was no damage to the Nichiha building. The amazing part is that we’ve had several freezes and lots of rain and absolutely no damage. And, man, it was hot. I can assure you when those gusts were coming, it was 500 to 550 degrees [Fahrenheit].
Linda loaded up the family pets as she prepared to evacuate with her mother, who also lived at the home. After getting everyone in the car, Linda returned to the house for a laptop. Back in the car, she considered going back into the house a second time to retrieve her mother’s wedding ring, but before she could do so, a nearby redwood tree caught fire and fell through the back of the house. It was a nightmare scenario. To escape, Linda had to drive a quarter of a mile through the fire with flames on both sides of the car as well as underneath and going over the top. In parallel, on the other side of the house, Bob retreated back to the home office. “I was going to start putting some sprinklers on before the fire came. I got the hoses on the east, and the north, and the south side, and I started wetting down the deck. The front was a redwood deck, which was 10 feet by 6 or 7 feet. If the deck caught on fire, it would burn the building down from the other side. When the gusts came, I would hide by the entry way.” Although Bob would continue working to preserve the rest of his property, his custom-built house did not survive. “There was no time to be terrified. Our house burned down in 15 minutes. The winds were blowing hard. All of the aluminum in the house was blown into a big pool where the living room used to be.” The wind gusts converted every bit of organic matter it could capture into flaming projectiles. Leaves from a nearby cemetery and debris from local vineyards and trees were hurled in every direction as baseballsized clumps. For at least three hours, with winds ranging from 40 to 60 miles per hour, the home office was battered with embers. “There was no damage to the Nichiha building. The amazing part is that we’ve had several freezes and lots of rain and absolutely no damage. And, man, it was hot. I can assure you when those gusts were coming, it was 500 to 550 degrees [Fahrenheit]. Everything in the backyard caught on fire instantly. I mainly stayed on the porch and entryway of the Nichiha house. When the gusts would calm down for a moment, I would go and wet everything down. Wet the east. Wet the entryway. Keep the deck out front soaking wet. Things would catch fire again after I put them out. Our place was always mowed and plowed. But the fire came across an acre and a half of plowed garden — that had sprinklers on it. The fire came across anyway. This was an act of nature.” All of the bushes on the property caught fire. The flames incinerated 120-foot trees that Bob had planted himself in 1985 when he first moved to the area. Everything that was organic burned. Still, the Nichiha siding, and the structure it protected, endured. “This stuff is amazing. It was battered all night long, with embers like ping-pong balls hitting the siding. For about three hours.” Sadly, none of the homes in Bob’s neighborhood survived. With over 200 houses incinerated, the community lost about a quarter of its homes in just a few hours. Bob made it through the event without injury. After the fire went out, he walked past the barricades to the nearby firehouse, where he had been a volunteer for 22 years. Although the Gates family lost their primary home, they have continued to live on their property by moving into the home office. “We’ve got this gorgeous building we’ve been living in. People stop by all the time and ask us how this redwood house survived. Lots of people. We keep a bunch of Nichiha brochures here and everyone’s taking them. We have a friend that was siding a new home in Napa and she had her contractor stop so they could pick out a Nichiha product. Nobody wants the exposure. We are definitely putting Nichiha on the new house. It might not save you from everything, but it will certainly save you a lot. It was a real layer of protection.”
CONCLUSION
Fiber cement is not magic. It will not render homes and businesses impervious to all environmental threats. However, in concert with manufacturer-recommended installation instructions and best practices, fiber cement enables homeowners and businesses to better protect structures and people. As another layer of protection, fiber cement improves resilience while retaining the versatility to satisfy aesthetic preferences from ultra-modern to more natural.
ABOUT NICHIHA
For over 60 years, architects, builders, and contractors have turned to Nichiha fiber cement cladding to push beyond the boundaries of the commonplace. Founded in Japan in 1956, Nichiha boasts over 2,800 employees and 13 plants worldwide. Nichiha USA is a leading manufacturer of fiber cement siding and Architectural Wall Panels for commercial and residential applications. Our Architectural Wall Panels provide state-of-the-art technology with limitless design possibilities. No other cladding provider offers as many options, colors, textures and styles. Whatever your design intent, Nichiha has a solution to help you achieve it. This includes the look of metal panel, stone, concrete, wood, brick and much more.
