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Written by Deb Kingsbury
Living on a 36-acre off-grid property in northern Arizona, Deb and her husband Jeremy embrace sustainable living through solar power, rainwater harvesting, and a passive solar home built with recycled polystyrene block. A freelance writer and editor, Deb grows food in raised beds and a greenhouse and is an avid hiker and backpacker. A long-time search & rescue volunteer, she has published two novels and previously homesteaded on the East Coast.
We looked into rammed earth and strawbale. We considered cob and adobe brick. And earthship construction. And hempcrete and repurposed shipping containers, too. You name it, and if it was an innovative, sustainable building material, we probably explored it for the home we were planning to build at 36-Acre Wood.
Then the architect who was designing our passive solar, off-grid house with a potable rainwater system introduced us to what was behind his own plastered and stuccoed walls: insulated concrete forms (ICF), specifically EF Block™ in our case (EF = Earth Friendly). As we had with the other materials, we weighed the pros and cons—there were more of the former than the latter for us—and we were sold.
In a world increasingly focused on sustainability, builders and homeowners, including owner-builders like us, are seeking innovative solutions that combine environmental consciousness with structural integrity, not to mention affordability. Enter ICF block—a game-changer in sustainable construction.
These innovative building materials combine the strength of concrete with the insulating properties of recycled foam. In this blog post, we’ll cover what ICF blocks are, how they’re made, their properties, how to build with them, and the pros and cons.
ICF Block Table of Contents
What Are Insulated Concrete Forms (ICFs)?
ICF blocks are a construction system that uses rigid formwork to create reinforced concrete walls. They consist of lightweight interlocking foam blocks that serve as insulation and formwork to create the skeleton of your building.
Once the blocks are in place, concrete is poured into their hollow centers, resulting in a sturdy, well-insulated, energy-efficient structure.
But here’s the twist—they’re not just any foam; they’re made from recycled expanded polystyrene (EPS), commonly known as Styrofoam. So, instead of it ending up in the landfill and sitting there for about 500 years, you can build a very well-insulated, durable, and fire-resistant home with it, among other things.
How Are ICF Blocks Made?
As mentioned, the blocks are primarily made from recycled Styrofoam (8% in the case of EF Block). The EPS foam is molded into interlocking sections, resembling oversized Lego bricks, with minimal waste.
These blocks are lightweight—our 5-foot x 1-foot x 10” blocks weigh about 45 lbs each—easy to handle, and provide excellent thermal insulation. The interlocking design simplifies installation, making it a favorite among DIY builders and some general contractors we know who appreciate efficiency and sustainability.
Properties of ICF Blocks
When it comes to sustainable construction, ICF stands out. These foam blocks offer more than meets the eye. 🏗️🌿
Structural Strength and Durability: ICF construction combines the strength of concrete with the insulation properties of foam, resulting in robust and durable walls.
Energy Efficiency: ICF walls offer exceptional thermal performance. The foam insulation keeps indoor temperatures stable, reducing your reliance on heating and cooling systems. Our EF Blocks have an R rating of 40.
Soundproofing: The foam insulation dampens sound, creating quieter indoor spaces.
Fire Resistance: ICF walls are fire-resistant, protecting against flames and high temperatures.
Air-Sealing: The snug fit of the interlocking blocks creates airtight walls, minimizing drafts and keeping your home comfortable year-round.
Affordability: At least when we were building, ICF construction cost considerably less than lumber. Including the rebar and concrete pours, our cost was about $7 per linear foot.
Flexibility: While they don’t actually bend, ICF blocks lend themselves to creative designs, including arches, curves, and even sculpted walls.
How To Build with ICF Block
So, you’ve decided to embrace sustainable construction and dive into the world of ICF. But wait—aren’t these high-tech foam blocks reserved for seasoned contractors?
No, ICFs aren’t just for the pros; they’re also a friendly companion for owner-builders. With a relatively small learning curve (which the company we purchased from provides upon request), ICF blocks are easy to work with and forgiving, too, if you make a mistake.
So, with a dash of education and a sprinkle of determination, you can stack ICFs like a pro in no time. 🌱🔨
Here are the basic steps:
Foundation: Start by laying ICF blocks for the foundation and stem wall. It’s like assembling a giant puzzle but with more concrete and fewer missing pieces. The blocks can be joined with mortar, like brick-laying, or with a special glue.
Wall Construction: To reuse the analogy, stack the ICF blocks like Lego bricks. Ours are offset like a brick wall, but we’ve seen a large home built with ICF blocks by stacking them in line, directly on top of each other. Reinforcing steel (rebar) is placed inside the blocks to enhance structural integrity.
Pouring Concrete: Once the blocks are in place, pour concrete into the hollow cores. The concrete bonds with the foam, creating a solid wall. Note that we built our ICF in stages, beginning with the stem wall and then going up about four or five layers of block at a time. We did this due to county code requirements, with an inspection at each level.
Finishing: After curing, you can finish the walls with various materials, such as stucco, siding, or plaster.
ICF Pros and Cons
The pros have the upper hand here.
Pros of ICF Construction:
Strength: ICF walls are robust and resistant to natural disasters. ICF homes feel secure… because they are.
Material Efficiency: Earth-friendly ICFs use less concrete compared to some traditional methods. ICFs reduce waste and promote recycling.
Time-Saving: ICFs speed up the building process with their quick installation due to interlocking blocks.
Energy Savings: Excellent insulation reduces heating and cooling costs. (Our passive solar ICF home stays comfortably warm in the winter, even in freezing temps, without additional heat. The only time we use the wood stove is when we have a stretch of two or more cloudy days with freezing temps.)
Quietude: Enjoy peace and quiet (unless maybe your closest neighbor plays the bagpipes). ICF block doesn’t block all outside sound, of course (and I don’t think anyone would want it to), but it does dampen it quite a lot. We often don’t even hear the noisy UPS truck drive up.
Cons of ICF Construction:
Cost: ICF construction can be slightly more expensive upfront than some other methods (but less than others).
Learning Curve: Contractors and owner-builders need some training to work with ICFs effectively.
Curing Time: Concrete curing may take longer due to insulation.
Types of ICF Block
Insulated concrete forms come in various categories:
Flat-Panel ICFs: These ICFs consist of flat panels that interlock to create the formwork. They’re versatile and suitable for both residential and commercial projects.
Grid Systems: Grid-style ICFs have a grid pattern, allowing for precise placement of reinforcing steel (rebar). They’re popular for walls with complex shapes.
Block-and-Panel Systems: These combine the benefits of flat panels and traditional block forms. The panels provide insulation, while the blocks offer structural support. The EF Block™ we used leans toward the block-and-panel approach, emphasizing insulation and strength.
Post-and-Beam ICFs: These ICFs are designed for larger spans, such as creating arches or vaulted ceilings. They use vertical posts and horizontal beams.
Tapered ICFs: Tapered forms allow for curved walls, making them ideal for unique structures. They’re often used in custom homes and artistic projects.
What Can ICF Block Be Used For?
If it can be built, it can probably be built with ICF blocks. While they're primarily used in construction to create energy-efficient and resilient buildings, they can also be used in various other creative ways.
Here are some common applications:
Residential Construction: ICFs are widely used to build energy-efficient homes. They can be used for single-story residential and commercial buildings, high-rise projects, basements, underground homes, or entire multi-story homes. Some builders use only insulated concrete foundation forms and combine them with other building methods above ground.
Commercial Buildings: ICFs have found applications in commercial construction, particularly for structures that require strong thermal performance and fire resistance. Commercial ICF construction has strict standards, codes, budgets, and timelines to follow.
Multi-story Buildings: ICF blocks have been used for walls surpassing 40 feet of unsupported height. The tallest ICF structure is a 23-story building in Waterloo, Ontario.
Disaster-Resistant Buildings: Due to their strength and durability, ICFs are often used in regions subject to regular hurricanes. They exceed safety, resilience, and durability requirements for FEMA-ATFP Federal Military Standards.
Custom Homes and Specialty Projects: ICFs can also be used for custom homes and specialty projects with unique, creative designs.
We’ve also seen ICF blocks used to create public benches and planters, and we’ve used leftover blocks for these applications on our own property. Here are some ways ICF block lends itself to unique, creative designs:
Flexibility in Design: ICFs are flexible and can accommodate most any size or style of design a homeowner or architect can dream up. They're simple to cut and shape.
Customized Architectural Effects: ICFs can include customized architectural effects, such as curved walls, large openings, long ceiling spans, custom angles, and cathedral ceilings. This allows for the creation of unique and aesthetically pleasing designs.
Sculptural Walls: The strength and flexibility of concrete allow ICFs to be used for creating sculptural walls. These can be custom-designed and shaped to fit the specific needs of a project.
Outdoor Structures: Beyond buildings, ICFs can also be used for constructing outdoor structures like benches, planters, and even sculptural elements. Their durability makes them suitable for these applications.
Artistic Designs: Creative and artistic architects design unique and beautiful structures that reflect the owners and culture. ICFs provide a superior architectural design solution for any home or building style.
More About EF Block™
EF BlockTM is an innovative ICF product manufactured by Earth Friendly Building Materials LLC (EFBM), established in 1990. These blocks are easy to stack and shape, allowing for versatile construction designs. EFBM, based in Arizona, has been involved with over 10,000 completed ICF projects throughout the US and Mexico.
While most ICF products share the same qualities, we chose EF BlockTM because the company's owners happened to have a home in our area and were very responsive to our calls and emails. They connected us with a local subcontractor who’d built his own home with their ICF product and was able to assist us with ours.
Here are the details about EF BlockTM:
Built-in Thermal Insulation: EF BlockTM has thermal insulative qualities equivalent to an R-40 insulation rating.
Hurricane (Wind) Resistance: These blocks are 700% stronger than a typical 2x6 frame with a 1/2-inch shear wall.
Mold and Mildew Resistance: EF BlockTM keeps your home mold-free and fresh.
Fire Resistance: EF BlockTM has a 4-hour fire rating, which is beneficial for those who live in an area at risk from wildfires.
Easy Installation: EF BlockTM is fairly easy to install, saving construction time and labor costs.
Bug Resistance: Termites won’t nibble on these blocks.
Green Building Material: Made from 87% recycled post-consumer Styrofoam, EF BlockTM is a sustainable choice.
Other ICF brands may have different features, shapes, and sizes. Some emphasize ease of installation, while others prioritize specific performance characteristics.
For more information about this type of ICF block, as well as the Earth Friendly Building Material’s gallery, training program, and their role as Arizona’s #1 EPS recycler, check out their website at EFBM.com. (Note that we’re not affiliated with this company in any way and don’t earn any commission if you click this link and end up purchasing from them. We’re simply past customers who were happy with their service and very happy with the product.).
Where Else To Buy ICF Block
If you’re looking to purchase insulated concrete forms for your construction project, here are some other retailers and stores, among many, that sell and ship them:
ICF blocks aren’t just building materials; they’re a sustainable lifestyle choice. So, whether you’re constructing a cozy cottage or a modern mansion, consider the ICF alternative.
🌿🏠🔨
ICF Block FAQs
What is ICF block, and why is it considered a sustainable building solution?
ICF (Insulated Concrete Form) blocks are high-tech foam blocks used in construction. They provide excellent insulation, reduce heating and cooling costs, use less concrete than traditional methods, and promote recycling, making them a sustainable building solution.
How do you construct a wall using ICF blocks?
To construct a wall with ICF blocks, you start by laying the blocks for the foundation and stem wall. Stack the blocks like Lego bricks, place reinforcing steel (rebar) inside, and then pour concrete into the hollow cores. Finish the walls with stucco, siding, or plaster after the concrete cures.
What are the pros and cons of using ICF blocks in construction?
Pros include strength, material efficiency, time-saving, energy savings, and noise reduction. Cons include a higher upfront cost, a learning curve for proper installation, and potentially longer concrete curing times due to insulation.
What types of ICF blocks are available for different construction needs?
Types of ICF blocks include Flat-Panel ICFs, Grid Systems, Block-and-Panel Systems, Post-and-Beam ICFs, and Tapered ICFs. Each type offers different benefits, such as versatility, structural support, and the ability to create unique designs.
What are some common applications for ICF blocks in construction?
ICF blocks are used in residential construction, commercial buildings, multi-story buildings, disaster-resistant buildings, and custom homes. They can also be used for outdoor structures, public benches, planters, and sculptural elements.
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