Rebuild Fire Resistant Houses

 

Homeowners in the U.S can build and improve their homes to be more resilient against increasing climate extremes. We aim to educate homeowners about relevant climate risks and solutions to reduce potential damage to homes and save lives. In this series of blogs, we share stories of climate-resilient homes.

Eric Miller, a Building Enclosure Professional and Insulated Concrete Form (ICF) Specialist, LEED AP BD&C, shared his experience and his recent work on residential projects focused on fire resilience and his take on what it means to build right and how to build a fire resistant house.

 

Miller supported the rebuild of the Daily Residence in Santa Rosa, CA after they lost their home in the Tubbs fire in 2017. Miller visited the fire-ravaged region property before the rebuilding and witnessed staggering devastation. Everything was incinerated including portions of the remaining concrete foundations. The Dailys wanted to rebuild with a material that was less flammable than wood and still environmentally friendly. They chose Insulated Concrete Forms (ICFs).

 

 

 

 

 

Before the Tubbs wildfire struck, the risk of wildfire was not on the Dailys’ minds. After losing their home, they decided to choose an alternative to wood that would be less flammable and improve the home’s thermal stability and energy- efficiency. Although ICF buildings are not 100% fireproof, Daily believes that they are much more fire-resistant relative to wood. Another consideration for the ICFs was their rigidity during seismic events since the Dailys’ property is located a mile away from an earthquake fault line. In fact, they recently experienced a 5.1 earthquake in October 2022, and they felt safe in their home being more resistant to seismic shaking relative to wood. Read about building strategies for earthquakes in our blog.

 

The Dailys have been living in their ICF home for over a year. The thermal stability is significantly noticeable because the house maintains a moderate livable temperature. Approaching the end of October 2022, neighbors had already turned on the heaters while the Dailys didn’t need to. During the summer, they hardly used their air conditioner. On top of the thermal benefits of an ICF building enclosure, they utilize natural ventilation augmented by a whole-house fan and the location and design of the openings. Another noticeable benefit of the ICF is the sound resistance. Although relatively close to a road, they feel their home is especially quiet.

  

Living in a Wildland Urban Interface (WUI) area, the Dailys are aware they can’t purchase wildfire insurance. They were surprised that many insurance companies still aren’t familiar with the ICF benefits related to fire resilience and energy efficiency, and it is more challenging than it should be to find companies that offer insurance or discounts for resilient features. The minor cost-increase of building with ICF can be reduced once organizations and municipalities become more informed of  ICF as a building material and the relative speed of ICF construction, which is arguably faster than traditional and less fire-resistant methods. . 

 

One of the projects Miller is now working on is supporting the rebuilding Matt Morris’s home. Morris is an architecture professor at the University of Boulder, CO, and the founder of Construction Education. Matt and his family lost their home to the Marshall fire in the Superior Louisville area in 2021. Morris also chose to build with ICFs and is currently demonstrating how to get an ICF structure up very quickly. 

 

Rebuilding these projects and touring the damage caused by firestorms, Miller observed entire subdivisions destroyed and he was deeply affected. “It was heart-wrenching and horrifying” were his words. In fact, Morris’s sense of trauma was so intense that his initial desire was to build a house that is all concrete with no windows to be as safe as possible from wildfires. You can listen to Morris’s story here. 

Understanding that the family narrowly escaped the wildfire emphasizes that if it happens again, they don’t want to leave their fate to luck. They wish to be protected and they need to adapt to the new risks.

 

Wildfire Risk

A home located in a Wildland Urban Interface (WUI) zone is at a higher risk for damage to wildfires. In recent years we have learned that not only the homes in WUI areas are at high risk of wildfire. Some people don’t realize their property is in a WUI zone. Underlining this point, Superior, CO, wasn't considered a WUI zone until the Marshall fire occurred. The risk level is also a factor of the immediate fuel sources on-site, the weather, the topography, and the assets at risk.

Back in 2007,  midway into the construction of his own ICF house in Park City, Utah, Miller  recognized that the house was located in a sea of scrub oak, a very dry tree that practically explodes in a fire. At the same time, he learned that the water infrastructure in that location wasn’t properly equipped to fight a fire, and some hydrants were not properly pressurized to receive water at all. That moment put the wildfire risk on his radar. Miller realized he was building a home in a dangerous area.

 

A hazard and risk assessment can help determine the level of mitigation that is needed for a building. The assessment, which can be conducted at a regional, state, or local level, needs to be both credible and professional to ensure that the analysis is accurate, comprehensive, and verifiable. Read more about wildfire risk in our Wildfire Blog.

 

Climate Resilient Strategies

 

ICFs: 

Like Leigh Overland, the owner of the Ash Creek House, Miller is a sound believer in Insulated Concrete Forms (ICFs). 

ICFs create monolithic concrete structures, formed and assembled with Expanded PolyStyrene (EPS) foam insulation blocks which are reinforced with steel rebar. Concrete is placed in the forms and the ICF blocks stay in place to serve as two layers of robust continuous insulation and create an attachment surface for drywall and cladding 

 

 

ICFs provide resilience in the face of strong winds and wildfires while increasing energy efficiency due to their air tightness and thermal control. The forms drastically reduce the thermal bridging which significantly increases the thermal comfort in the building. Other advantages are its resistance to mold and wood boring pests, as well as reducing sound transmission.

The Insulated Concrete Form Manufacturer Association (ICFMA) lists the top ICF companies and numerous resources. 

 

Nudura, for example, which is part of the Tremco Construction Products Group, brings building science to the ICF with systems such as weather-resistive barriers (WRBs),  flashings, sealants, and coatings that keep air and moisture out. Their company, Dryvit, manufactures a synthetic stucco that can be installed directly over the EPS foam. 

 

Additional Fire Resilient Design Strategies: 

 

Miller believes there is no such thing as a fireproof home. Yet, much can be done to make a building more resilient to fire. Here is a few of his strategies on how to build a fire-resistant house

For example, windows are a vulnerable element to fire and extreme heat caused by fire storms. Choosing inflammable materials for the exterior and fire-resistant windows should help increase fire resilience. 

The vents in vented roofs are also a vulnerable element through which embers can enter the house and ignite. Metal screens in the vents can reduce the embers from entering but Miller believes an even safer strategy is designing an unvented attic. Semi-conditioned unvented attics are recommended in fire-prone locations to avoid updraft of air along with embers from entering the house. 

 

In unvented attics, insulation is often applied to the roof area instead of above the ceiling. This semi-conditions the attic space and regulates the temperatures in the attic. It also helps increase the efficiency of any HVAC system located in the attic. The stabilized attic temperatures reduce the strain on the system eliminating the need to deliver hot air through a cold space or deliver cold air through a hot space. 

 

Many of these strategies and more are implemented within fire-resistant modular homes and fire-resistant prefab homes.

Lastly, a relatively easy strategy is to clear a defensible space around the building and think ahead for ways to prevent a potential fire from further spreading. Read more about fire resilience strategies in our blog.

 

Passive Solar Design:

 

This strategy aims to design your home to maintain steady temperatures throughout the year without the use of heating or cooling. 

This type of design will ensure that south-facing windows are properly shaded to reduce sun exposure in the summer. Also, seasonal protection of west-facing windows, preferably by planting deciduous trees on the west side of the building. The idea is to end with just the right amount of solar radiation that will heat your energy-efficient building during the winter and reduce overheating in summer, leading to a structure that would hardly need utility-based power to ventilate, heat, or cool.
Read more about passive solar design in our Heatwave blog.

 

HVAC

After ensuring the home is airtight, Miller recommends installing heat pumps for heating and cooling. He tries to avoid radiant heat claiming they are not the best fit for warm climates because the radiant systems are not as efficient in cooling as in heating. Heatpumps, on the other hand, are less expensive than radiant and fit most climates. They can perform well in cold climates despite the misperception that they don’t. This may include the sporadic use of electric resistance hybrid heat pump technology.  

To introduce fresh air to an air-tight building, Miller recommends installing Heat Recovery Ventilation (HRV) or Energy Recovery Ventilation (ERV). Depending on the climate and humidity conditions, you can consider an ERV that regulates humidity, as opposed to an HRV, which only deals with efficiently delivering fresh air

 

Challenges

The biggest and most frustrating challenge that Miller faces every day is introducing ICF as a new product to professionals that were trained to use certain products and have strong beliefs about traditional ways of building. 

 

An unexpected challenge is working with the green building industry. In the Louisville/Superior region, there is a push toward green buildings and passive houses. Although the resilience and energy-efficient qualities of ICF can align with sustainable building goals, there is a disagreement when it comes to ICF. Contractors who are not well familiarized with this product, believe it doesn't qualify for the Passive House standard. Miller is fighting off myths such as ICFs don’t have a high enough R-Value or are not sufficiently insulated. ICFs allow a very low flow of energy, they are highly insulated, are airtight, which is one of the main elements of a passive house. Moreover, a mass wall with continuous insulation is inherently better performing than a cavity wall. “There is more to thermal performance than nominal R-value”, Miller emphasizes, “and wood is inherently more difficult to air-seal than concrete.“

 

There is even a larger gap when confronting traditional construction. For example, there is still a false notion among contractors that a building needs to breathe. Miller emphasizes that a building doesn’t need to breathe, it needs to dry out. The occupants in the building need to breathe. He gives a nod to building scientist Allison Bailes, Ph.D., for expanding on this issue. As mentioned, the fresh air in an airtight building should come from an HRV or an ERV. 

Another example is that HVAC contractors use rough estimates for sizing the needed HVAC in a home. Instead, achieving the right sizing for ideal efficiency requires proper energy modeling. ICF walls and Passive House double stud walls dramatically reduce the air changes per hour (ACH), as well as the flow of thermal energy (heat gain/heat loss), reducing heating and cooling loads,  which is critical in the right-sizing of HVAC systems.

 

Some new code requirements raise a challenge by increasing the cost and time of construction. Some guidelines for fire focus on installation requirements of fire alarms and sprinklers, while there are other fire-resilient strategies that can be implemented with no/little extra cost. “I see the reason for requiring these fire suppression systems, however, we need to reduce initial costs and increase the speed of construction, not drive them even higher“ explains Miller. 

Cost may seem a barrier to ICFs as well. The incremental price of ICFs is a function of the price of the alternative materials such as wood, and the cost of ICF contractors' labor. Miller roughly estimates that ICF could be comparable in initial costs to wood construction with no more than a  5%- 7% increase over the costs of wood. 

 

There is still a long way to the full-scale adoption of ICFs. There is a lack of qualified contractors despite the ongoing training by Miller and ICF manufacturers. Gladly, there are people who choose to self-build with ICF and do very well. 

 

Building Codes

 

The Miller Integrated Design philosophy is to go beyond code to increase resilience through air tightness and a robust thermal envelope. 

When designing a new project, Miller leans on an integrated design approach to lower the energy load in the building. 

 

Not every jurisdiction adopts the most stringent codes. On top of the International Residential Code (IRC) that all jurisdictions follow (some more updated versions than others), in municipalities located in fire-prone areas, like WUI, more stringent amendments are adopted, such as CAL-Fire guidelines by the Office of the State Fire Marshal OSFM. The CALFire guidelines are being adopted beyond the State of California, such as in Oregon and Colorado. 

 

Spreading The Word through Miller Integrated Design and Beyond

Miller got thoroughly acquainted with ICF construction, working as a regional manager for Nudura for 7 years. It is a specialty he implements in Miller Integrated Design. His mission is to help people build better homes and buildings. The focus is building science and high-performance thermal enclosure technology. The core of that mission is energy use reduction and resilience. 

 

The importance of thermal comfort in buildings was instilled in Miller’s mind growing up in western Massachusetts in a typical New England “leaky old house.” Miller recalls watching his favorite TV shows bundled up in a blanket and sitting on the heating vent because the house would not hold heat.  

 

Miller designed and built two of his own houses with ICFs for his immediate family. The comfort was especially noticeable in his full ICF house in Utah. It was not drafty due to proper insulation and sealing, and quiet due to the ICF’s resistance to sound. As early as during construction in mid-winter, after sealing the house but without the heat on, the house was well over 45 degrees Fahrenheit even with 0 outside. When they moved in, the house exhibited a very low energy bill, roughly half of the energy use of similar size homes.
In Utah, during strong gusts of high winds, which would make most buildings shudder and shake, in their ICF house, they couldn't even hear the wind. There are stories of ICF buildings that lived through hurricanes. One of the more famous examples is an ICF house that survived a direct hit by Hurricane Michael on Mexico Beach, FL, while nearly every other house near it was destroyed.

 

 

Building his own home was a learning experience. He noticed the lack of communication and collaboration in the construction industry which led to missed opportunities. Miller decided to be part of the change and help the adoption of the build better approach. 

 

Miller worked as a teacher in a Trade School in North county San Diego. He taught integrated design in green buildings and led teams of students through the process of retrofitting homes for energy/water conservation.. 

 

Today Miller is assisting design teams, architects, engineers, owners, and developers to utilize the integrated design process.

He is a great believer in ICF but is open to other materials that better fit specific projects and climates. The company aims for faster, better, and more affordable construction. 

 

What we need

• Resilience requires collaboration and detailing. 
• The concentration should be on reducing the cost and time of construction, focusing on highly efficient buildings which start as early as the design phase to incorporate good thermal enclosure, energy modeling, and the right sizing of HVAC systems. 
• The design phase should include passive systems such as passive ventilation, passive solar, and whole house fans that help increase the occupants’ comfort before turning on the HVAC.
• The construction industry should increase and improve energy modeling, including thermal and HVAC load modeling.
• Many of the code requirements can be added without extra cost. It takes thinking outside the box or changing old methods. Miller believes we're going to see innovation and change that is mainly driven by a more stringent firewise and energy efficiency code. 
• More organizations should invest to get their product certified through CalFire. Miller is pushing product manufacturers to go ahead so they can appear on the list of allowed materials. 

 

Eco-Friendly?

Miller recalls representing Nudura in GreenBuild when a woman architect bluntly expressed her skepticism about the ICF’S relevance to the green building industry. “Well that’s a stretch,” she said, hinting at the Expanded PolyStyrene (EPS) foam which is a derivative of the fossil fuel industry. 

Miller acknowledges that although ICF contributes to fewer emissions due to its contribution to energy efficiency, the materials it comprises are not 100% eco-friendly. When comparing ICF to wood, which is considered renewable and eco-friendly, it’s crucial to consider where the wood is coming from, and how it is being harvested, treated, and managed. There are always pros and cons to every material.  Miller points out that the first net zero energy public school is a Nudura ICF building. “If we are shooting for net zero energy, then the robust insulative power of ICF is a great tool to achieve that goal” Miller added. 

 

The construction industry is also showing clear trends of movement toward using Cross Laminated Timber (CLT) which is considered a movement away from concrete and steel and highly carbon-emitting products.

 

The question of which product is best is challenging and depends on the location, the project, and the source of the material.

 

Another important factor of sustainability is using fewer materials when feasible. Resilient materials last longer, and therefore, are inherently sustainable when eliminating the need to redo projects and generate more waste. 

 

There are ways to increase the eco-friendliness of ICFs. For example, reducing the amount of steel or rebar by using micro-fibers in the concrete.  Euclid Chemical’s Tuff Strand is the Tremco CPG solution for this approach. There are companies that work on reducing the embodied carbon in concrete, such as CarbonCure. In the future, Instead of concrete, we can use hempcrete if it can be deemed strong enough to put inside the ICF walls. EPS  foam could eventually be made out of mushrooms/fungus, instead of the byproduct of the fossil fuel industry. 

Miller sees an evolution in the building industry toward better products but the transition away from traditional methods is challenging.

 

Final Thoughts 

ICFs are one of many ways to build a home. Having lived in an ICF home, Miller has never been more comfortable thermally or felt safer during windstorms. 

 

If people are thinking of ICF for their building, he would encourage them to pursue it. The benefits of energy efficiency and sound resistance add up to durability and resilience which are becoming a top priority. Its eco-friendliness can also be improved

Other than ICF, there are many additional strategies and materials that can improve a home’s resilience to different climate phenomena, depending on the prevalent risk in the location of the structure.

 

Unfortunately, when rebuilding after a disaster such as a wildfire, people are naturally more concerned about rebuilding fast and with minimum cost, rather than about wildfire risk mitigation, especially after having lost everything and not having a roof over their heads. 

 

On the one hand, owners who experienced catastrophic fires are reluctant to rebuild out of wood because of its flammable quality. Unfortunately, the fastest construction is perceived to be the familiar one, thus many victims rebuild with wood nonetheless and hope that the disaster they experienced would be once in a lifetime. 

 

Whether ICF or other climate-resilient materials and strategies, the transition to new construction materials and methods is challenging and takes time. Yet, if we don’t invest in building properly, and in climate-resilient strategies and materials, we will continue the cycle of having to rebuild time after time. Hopefully, we can engage in climate-resilient and proper building as a default so we can be better prepared before the next disaster strikes.