Pros & Cons of Insulated Concrete Forms ICF Blocks

November 27, 2020

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In this article, we’ll delve into the advantages and disadvantages of Insulated Concrete Forms (ICF) construction. If you want a visual guide on ICF block production and the chemical changes it undergoes, be sure to check out my factory tour video!

ICF walls are built using Fox Blocks, a popular choice known for its molded polypropylene plastic ties securing two layers of 2 ⅝” thick Expanded Polystyrene foam pieces. These blocks interlock like Legos, creating a strong and stable wall assembly. The blocks are available in various types, including straight blocks, corner blocks, T-blocks, 45-degree angle blocks, radius blocks, taper top blocks, curb blocks, and brick ledge blocks, catering to diverse construction needs.

Fox Blocks products:

Straight blocks make up 80% of ICF wall assemblies on most residential and commercial jobs.
Corner blocks have corner brackets designed to add more strength and support and eliminate blow-outs during the concrete pour.
T-blocks are used where 2 walls intersect like an exterior wall to an interior wall
45 degree angle blocks provide more design options. They also have a corner bracket to reinforce the vulnerable edge.
Radius blocks are 16” long specialty blocks used to build curved walls. They have to be specially ordered.
Curb blocks can create a ledge to support different floor systems like hollowcore, precast concrete, engineered wood floors, garage slabs, etc.

Building ICF walls

So how do you build ICF walls? After excavating the site, the concrete footing is poured on the perimeter walls with rebar sticking out of them. Next, the corner blocks are placed to define the edges. Straight blocks are then stacked in a running bond, staggered layout towards the center of each wall. Rebar or reinforcing steel bars, snap into the polypropylene ties of every single ICF block. After all the blocks are stacked, the wall is braced on one side.

Next, the concrete must be properly prepared because it is a vital part of the wall. The concrete in ICF walls must have a slump of 5” to 6” which is higher than a concrete mix for a floor which may be at 3”. The proper slump allows the concrete to flow and be pumped efficiently. A lower slump can create voids and honeycombs in the walls and create more hydrostatic pressure which can damage the blocks. The aggregate in the concrete must be between ⅜” to ¾”. Using a larger aggregate size may cause congestion between the form wall and the reinforcement resulting in voids.

Advantages

Strength and Durability: ICF homes are highly durable and can withstand extreme weather conditions, including hurricanes, tornadoes, and floods. The combination of EPS foam and concrete provides excellent resistance to external forces.
Fire Resistance: ICF walls have a high fire rating, making them ideal for regions prone to wildfires and fires in general.
Energy Efficiency: ICF walls offer superior insulation, reducing air leakage and energy consumption. They achieve impressive Home Energy Rating System (HERS) scores, making them more energy-efficient than traditional construction.
Soundproofing: ICF walls exhibit low sound transmission, creating quieter indoor spaces.
Air-Tightness: The continuous insulation in ICF walls prevents air infiltration, reducing condensation, mold growth, and energy loss.
Fast and Efficient Construction: Fox Blocks’ 6 in 1 assembly design allows for quicker construction, fewer on-site trades, and reduced chances of errors.
Versatility: ICF walls can be used in various construction types, including multi-story buildings, slab on grade, pier and beam homes, and more. They accommodate different exterior finishes.
DIY-Friendly: ICF construction can be a DIY project, saving costs if you’re willing to stack the lightweight foam blocks yourself.
R-Value: ICF walls offer impressive R-values, providing excellent thermal insulation.

Disadvantages of ICF Wall Construction:

Cost: ICF construction can be more expensive than traditional wood construction in certain regions.
Limited R-Value in Cold Climates: ICF walls may not offer sufficient R-value for extremely cold climates.
Waterproofing Challenges: Proper waterproofing may be required, and additional peel and stick membranes can add to the expense.
Complex Electrical and Plumbing Installations: Installing electrical boxes and conduits in ICF walls can be disruptive and may require additional planning.
Curing Process: Concrete curing in ICF walls releases heat and moisture, requiring proper ventilation to avoid humidity issues.
Reduced Interior Space: ICF walls occupy more space than their nominal thickness, potentially affecting interior room dimensions.
Environmental Impact: While ICF homes offer longevity and sustainability benefits, concrete production has a substantial carbon footprint.
Remodeling Challenges: Modifying exterior walls in ICF homes can be difficult and may require concrete removal.
Thorough Planning Needed: ICF construction demands meticulous planning to avoid complexities during installations and avoid running cables through EPS foam.

Conclusion

In summary, Insulated Concrete Forms (ICF) construction offers remarkable benefits in terms of strength, energy efficiency, soundproofing, and durability. However, there are considerations like cost, suitability for specific climates, and complex installations to weigh against these advantages. Ultimately, the decision to opt for ICF construction should align with individual needs, budget, and environmental concerns. As a sustainable and long-lasting building solution, ICF construction presents a compelling choice for those seeking superior performance and efficiency in their homes or commercial buildings.