When you think of building a solidly constructed home, you most likely do not think about foam as being part of it.
There are builders using it though, for good reason. When it is used in home construction—maybe as a marketing tactic—it’s not typically referred to as foam in the specification process, but rather as expanded polystyrene or EPS, which is a rigid, closed cell, thermoplastic foam material.
As a material, it has a lot of benefits. It is fully recyclable because it can be ground and then mixed with virgin expanded polystyrene to produce packaging or panels for walls. Other reasons it is becoming more attractive to home builders are its strength, its low cost, and that it is incredibly light weight.
So these are great motivators for builders to use it in home construction, and also for homeowners to accept it. Following are three builders proving success with foam construction.
System 1: Hercutech
First is the HercuWall system manufactured by HercuTech, an option attractive for its speed of construction, sustainability, and its acceptance in the insurance world, a feature that is becoming more and more critical.
The HercuWall system uses EPS foam, the same foam that is used as stucco backer board and is expanded into large blocks of a pound and a half density. The company creates 8” thick panels, allowing it to achieve an R-31 rating, which out performs wood at R-13 and concrete block at about R-3.
On top of the high R-value rating, the panels have tongue and groove assembly for a tight envelope instead of all the additional steps that would be necessary with other types of construction.
“We work with the largest insurance carriers across the country to educate them on what our product is made of,” said Jason Rhees, the CEO at Hercutech. “Because of Hercuwall’s combination of ESP foam, steel, and concrete, there is significant savings compared to wood and because of our hurricane ratings and fire testing, it allows them to insure these projects where they wouldn’t be able to insure wood or the cost of insuring wood isn’t feasible because it has gone up astronomically.”
The system also has no design limitations.
“Everything is designed with 3D BIM modeling and proprietary software,” Rhees said. “This digitized manufacturing process is all barcode driven and automated. Panels are produced and numbered in the order that they would be installed. Individual panels typically weigh 40 to 45 pounds, which can speed up construction and require less skill.”
After walls are standing, the interior finish is typical drywall, and the exterior is the architect’s choice.
Hercutech leaders shared that there are considerable savings in the working hours compared to traditional materials. Additionally, HercuWall elminiates downstream steps in the construction process and reduces municipal inspections.
“We can complete 10 units with a 5-person crew every week,” he said. “The installed price is anywhere from $11 to $15 per square foot, so it is cost competitive with highly insulated wood structures.”
Plus, using HercuWall, compared to traditional materials, simplifies the steps to qualify for the Energy Star program that gives back $2,500 per door or Net Zero Ready that gives back $5,000 per door, and also can get to net zero performance easier. Plus, due to the wall’s R-31 rating, the air conditioning can be downsized, giving significant operational cost savings.
“We have completed a use-phase performance lifetime cycle assessment validating the energy savings and carbon emission savings,” Rhees said. “The amount of concrete in a HercuWall system compared to ICF is significantly less. Hercuwall can replace up to 60% of wood and recycles 99% of scrap material.”
Compared to a conventional wood frame, there is up to a 70% labor reduction. Plus, the skill level of the laborer changes. For HercuWall installation, the foreman is higher skilled but leads a crew of general laborers who complete the installation. Panels just need to be moved in place, stood up and screwed together. A 2,000-square-foot home can be stood up in 2 hours or less with the concrete integrated in 45 minutes.
Even with the speed, sustainability and lower cost, there are other benefits as well.
“From a fire aspect, we are classified as joisted masonry and the EPS foam is self-extinguishing,” said Greg Garrison, who serves as the vice president of construction at HercuTech. “When a fire gets to it, the EPS recedes from the fire and doesn’t continue to burn.”
HercuWall has one- and two-hour fire rated assemblies. If the fire gets inside the home, the concrete and steel walls are noncombustible, so they remain standing for a longer period and protect whoever is inside by giving them more time to get out. HercuWall is Florida State, Miami Dade compliant, and Texas Department of Insurance high velocity hurricane zone approved over 300 mph winds.
In 2022, more than 30 homes in Florida that were built with HercuWall were hit by Hurricane Ian, including some that were in the eye of the storm. HercuTech went to assess the damage and reported no structural damage, no flooding, no property damage, and, most importantly, no loss of life.
System 2: SABS Building System by Strata
Already in use for decades around the world, SABS is a newer entry in the U.S. It is a composite building system that replaces wood and steel with EPS as the core material for all structural elements, including the walls, roof, and floor.
The EPS foam, mainly supplied by Atlas Molded Products, is coated with Strata’s mixture called Sabscrete which consist of sand, cement, glass fiber, and other additives to create a durable building shell that can go beyond the testing protocols and load standards set by the International Code Council-Evaluation Service.
“SABS exclusively relies on foam as the primary framing material, completely eliminating the use of wood, steel, or any other framing products other than foam as the main framing product in its construction,” said Amir Saebi, the vice president at Strata International Group, the creators of SABS with headquarters in Phoenix.
The company is mainly building custom homes and has little problem convincing these homeowners who want the top technology for their home to adopt a fairly unusual product.
“It’s the developers who need proof,” said Saebi. “They have to be trained and certified to use the product by Strata. Strata charges a fee of $5,500, which covers the expenses associated with training, certification, tools, and supplies for the course. We also closely monitor builders and visit project sites throughout the first year of product usage.”
When it comes to the design and permitting phase, Strata primarily oversees the structural aspects of the blueprints. However, Strata does have an in-house design team capable of providing assistance for blueprints on architectural, electrical, plumbing, and site planning, but not for mechanical and civil aspects.
The structural aspect needs to happen through Strata to meet ICC code and to maintain quality control. Saebi has a 666-page document with testing examples from the Finite Element Analysis (FEA) testing that it underwent to achieve the highest quality available.
The testing is similar to what NASA and Boeing use for spacecraft. The SABS product was subject to intricate simulations that resulted in more than 150 pages of structural load calculations showing how it will respond under varying conditions, such as fire, earthquakes, and storms.
“Results of the SABS FEA can be extensive and sometimes over 100s of pages, which is why it was never made for traditional construction and why it was so hard for SABS to get through code, until the ICC-ES approval code,” he said. “If an earthquake hits, you can see the loads that hit. If it is too much load, the simulation shows how it falls apart. This software was designed for heavy duty machinery and space craft to calculate loads in a simulation format and not done in a normal structure. When we proved our theory, other engineers are able to bring products to life using the same method.”
The fire treatment is equally impressive. Hit with direct flame from a flame torch, the SABS would not catch on fire. Invented by BSAF, together with SABS, it offers one of the highest fire ratings available.
“Developers are skeptical that we can meet their demands on cost,” Saebi said. “They realize it’s too good to be true for its affordable pricing.”
The EPS used has a density of 1.5 pounds per cubic foot, which gives it strength, while also making it cost effective. The cost for materials, regardless of the structure type, remains steady at close to $35 per square foot.
When considering both estimated labor and the SABS components, the total cost is approximately $70 per square foot, depending on the specific build and design. This price covers various components, such as exterior and interior walls, a roof made using the SABS System that eliminates the need for a truss system, and insulation. The envelope’s R-value averages between R-75 to R-100.
With that high of an R-value, the homes operate efficiently and reduce energy costs. For instance, in a hot state like Arizona, a 3,000-square-foot house costs of an average of $300 to keep cool in July, while a SABS home averages $80.
The SABS method also can reduce labor. Construction teams of up to 6 plus heavy machinery are reduced to only 4 people since the lightweight nature of the foam frame eliminates the need for machines. Even the roof installation can be done without a pulley system or crane—just two individuals can lift it. A recent 3,200-square-foot SABS home with a hip-pitched roof was framed by a 3-person crew in under 45 days.
EPS resists aging, mold, and insects due to its inorganic nature. One small downfall of the material can be yellowing from direct exposure to sunlight, which can be quickly cleaned with a power wash and brush technique.
The SABSCRETE material offers alternatives for finishes, replacing traditional options like stucco with a smooth textured finish.
“We moved in last September 2021,” said Shirley and Tad Halladay of their new SABS home. “The average cost of an average stick house in southern Utah was around $267 square foot. This house cost me around $100 a square foot. So, it cost about $310,000 to build this 3,200 square foot house including the 1,008-square-foot garage. This is with 12-foot ceilings on the first floor and 10-foot on the second. After we were done the insurance agency appraised to replace it at $780,000. Not bad.”
System 3: VERO Building Systems
Florida-based Vero Homes uses structural concrete insulated panels or SCIPs that are prefabricated foam panels with an insulated core of rigid EPS between two sheets of welded wire fabric mesh. Typically, the panels start at 4’x8’, but can be prefabricated up to 40’ long. The panels are connected during construction and coated on both sides with concrete for additional strength.
Panels used for load bearing walls are generally five inches thick. The panels can withstand 200 mph winds, seismic activity up to 8 on the Richter scale, have a 2 to 4-hour fire resistance rating, and are termite-resistant.
The panels are also energy efficient, with insulation values starting at greater than R-9 and up to R-37, compared to a typical stud wall that VERO calculates to be around R-8. This value does not include the air tightness of the system nor the thermal mass advantages that increase the R-value.
The panels are made with recycled and sustainable materials and the protective concrete structural coating can last 100 years. All of the materials also can be reclaimed and recycled when the life cycle is complete.
More detail about that VERO Building System is included in this recent article on resilient home solutions.
The future of foam
Hercutech has created a very capital efficient process to expand manufacturing plants from market to market.
“Because of manufacturing, digitization, and automation, we can set up in a matter of months at a fraction of the cost,” Rhees said.
So, more plants may be in your area soon.
A continued focus on sustainability in the built environment will make foam more popular. With 27% of our lumber imports coming from Canada according to the National Association of Home Builders, and Canada experiencing the worst wildfires in decades, these systems have the advantage of not using lumber.
Plus, the lifespan of the product is increasingly a consideration as lifecycle assessments become more mainstream. The longevity of these EPS-based systems can last more than 150 years.
Read the full article here
