Insulated concrete forms (ICFs) have revolutionized the construction industry, offering a robust and efficient alternative for building retaining walls. Homeowners looking to create usable flat space, correct slopes, or hold back earth will find ICF retaining walls to be an economical, flexible, and attractive option.
This guide explores the benefits of ICF retaining walls, comparing them to traditional options such as concrete masonry units (CMUs) and structural insulated panels (SIPs). It also provides insights into why ICFs are becoming the go-to choice for many homeowners and contractors alike.
Understanding Retaining Walls
Retaining walls can serve multiple purposes in both residential and commercial landscaping and construction, offering the structural integrity to reshape the land. You can use them for:
- Correcting slopes and embankments
- Holding back earth
- Creating usable flat space for patios and gardens
- Supporting roadways
- Controlling erosion along shorelines
- Creating tiered landscaping
- Surrounding pools
A retaining wall’s effectiveness depends on its ability to withstand pressure and resist deterioration. While you can use various materials to build retaining walls, three options stand out—CMUs, SIPs, and ICFs. Each has its merits, but ICFs are gaining popularity for their unique combination of strength, efficiency, and versatility.
How Do ICFs Work?
Insulated concrete forms are the cutting edge in retaining wall construction. They create concrete walls framed by foam forms, offering a unique combination of strength, efficiency, and versatility.
To make ICFs, manufacturers mold expanded polystyrene (EPS) into interlocking blocks and planks. To make retaining walls, technicians stack the lightweight forms and pour reinforced concrete into them. The forms remain in place, creating a finished wall surface.
Like all concrete structures, ICF retaining walls need proper reinforcement. Installers typically use steel rebar or helicon bars to strengthen the concrete core. The specific reinforcement pattern will depend on the wall’s height, soil conditions, and expected loads.
Most residential ICF retaining walls should be 8 to 12 inches thick. For commercial projects or walls requiring extra height, you may need thicknesses of 12 to 24 inches. Consult with a professional engineer to determine the appropriate thickness for specific projects.
Advantages of ICF Retaining Walls
The advantages we’ve outlined below make ICF the simplest, strongest, and most attractive retaining wall option for residential and light commercial projects.
1. Faster, Simpler Construction
Installing ICF blocks is straightforward and significantly faster than laying heavy CMUs. The process requires no mortaring and minimal training, allowing even inexperienced crews to work efficiently. ICF installations can be up to five times faster than building block walls, allowing you to complete projects faster.
2. Lower Skill Level Needed
The simplicity of ICF installation means you can use smaller crews with fewer specialized skills, reducing labor costs.
Training for ICF installations typically takes less than a day, making it accessible to homeowners and contractors. The lower skill levels needed makes the cost of ICF projects doable for a broader range of budgets.
3. Design Flexibility
One of the standout features of ICFs is their adaptability to various designs. You can easily cut the EPS forms to create curves, angles, and steps.
This flexibility allows you to build unique accent walls with peaks, valleys, or smooth curves—designs that would be challenging or even impossible with CMUs or SIPs.
4. Enhanced Durability
ICF retaining walls boast superior durability compared to alternatives. The combination of EPS foam and reinforced concrete creates a structure that:
- Resists rotting, warping, and cracking
- Withstands freezing and thawing cycles
- Provides excellent moisture resistance
- Includes integrated water barriers for flood protection
These strengths add up to a significantly longer lifespan for ICF retaining walls, often outlasting CMU or SIP alternatives by decades. They also mean reduced maintenance and repair costs over the wall’s lifespan.
5. Attractive Finishes
ICF forms remain in place after construction, instantly creating a finished facade—eliminating the need for additional facing to hide imperfections, as is often necessary with CMU walls. The EPS surface readily accepts various finishes, including paint, stucco, stone veneer, and brick facing, helping you achieve the look you want without sacrificing structural integrity or performance.
Other Common Retaining Wall Materials
Besides ICF, CMU and SIP retaining walls are still common.
Concrete Masonry Units (CMUs)
Concrete masonry units have long been a staple in construction. These blocks, formed from a mixture of Portland cement, aggregates, and water, offer a solid and durable building material. CMUs come in various styles, including hollow, solid, and interlocking blocks.
Builders typically stack CMUs like bricks, using mortar to bond courses. Some styles, like keystone blocks, rely on weight and interlocking shapes rather than mortar for stability.
While CMU retaining walls provide strength and longevity, they come with drawbacks. They’re labor intensive and take longer to install. They also require decorative facing for an attractive finish and have limited design flexibility.
In addition, CMU walls often need additional weatherproofing measures and procedures to enhance their resilience, especially in harsher climates.
Structural Insulated Panels (SIPs)
Structural insulated panels appeared in the 1950s as an innovative building material.
They consist of rigid foam insulation sandwiched between two structural skins, usually oriented strand board (OSB).
While less common for retaining walls, SIPs have a faster assembly compared to CMUs, along with built-in insulation.
However, SIPs have limitations when used for retaining walls. First, the OSB-facing portion is vulnerable to moisture damage, and it’s hard to adapt to curved or angled walls. It also has limited design options.
Final Thoughts
Insulated concrete form retaining walls are a big advancement in construction technology, offering a perfect blend of strength, efficiency, and design flexibility. For homeowners looking to create durable, attractive retaining walls with minimal hassle, ICFs provide an excellent solution that outperforms traditional methods in many respects.
While the initial cost of ICF construction is slightly higher than some alternatives, the long-term benefits in terms of durability, energy efficiency, and reduced maintenance make it a wise investment for most projects.
FAQs About ICF Retaining Walls
How thick should an ICF retaining wall be?
Most residential ICF retaining walls are 8 to 12 inches thick. Thicker walls from 12 to 24 inches suit commercial projects or extra-tall walls. A professional engineer should determine the right thickness.
Can you build curved ICF retaining walls?
Yes—the flexible foam forms easily bend and shape to create smooth curves, letting you create unique accent walls.
Do ICF retaining walls need reinforcement?
Yes. Steel rebar or helicon bars reinforce the concrete core against pressure loads. The manufacturer or an engineer can recommend the ideal rebar grid.
Does ICF have a smooth finish for retaining walls?
ICF forms create a smooth wall that’s ready for finishes. Paint, thin veneers, plaster coats, or exposed form joint patterns are common options. No added facing is required.
