You may have heard of ICF construction, but don’t really know what it is. But what is ICCF construction – is it the same or different than ICF? Let’s define the terms, then we can compare the two technologies.
ICF construction
First ICF, the acronym stands for Insulated Concrete Form and builders around the country are using them to build load-bearing walls. There are several companies making ICFs, but they are all very similar. The wall is basically a reinforced concrete wall, where the concrete has been cast-in-place between two layers of insulating material. Examine the photo below.
The insulation is typically two layers of 2” thick expanded polystyrene foam (similar to those packaging peanuts). The construction team will use plastic ties/spacers to hold the insulating panels in place. Additionally, the team will place steel rebar in the structure both vertically and horizontally per structural engineering specifications. This assembly creates a “form” for the casting of concrete. The concrete core is typically 4 to 8 inches thick depending on engineering requirements. Once the walls are completed, the interior and exterior surfaces of the wall can be finished according to the homeowners’ wishes.
ICCF Construction
Before we rush out and buy an ICF home, let’s consider the ICCF home. ICCF stands for Insulated Composite Concrete Form, which is a cousin to the ICF, but has important differences. Examine the photo below. Like the ICF wall, we have a reinforced concrete core sandwiched between two layers of insulation. The structural engineer will specify the amount and placement of the steel rebar. Both the interior and exterior surfaces can be finished per the homeowners wishes.
Differences between ICF and ICCF Walls
Amount of Concrete
Comparing the ICF and the ICCF figures, we notice that the ICF wall has a solid mass of concrete for its core, 4 to 8 inches thick – that’s a lot of concrete! Whereas the ICCF wall has a concrete core that resembles a giant waffle. The concrete grid is typically 4 to 6 inches thick, with 12 inches between grids (center to center). This means that the ICCF wall uses a lot less concrete that the ICF wall (about 45% less) [1]. Because an ICCF wall has less concrete, there is more room for insulation. This means that the ICCF wall has a better insulating capacity than an ICF wall of equal thickness.
Insulating Material
Another important difference between ICF and ICCF walls in the insulating material. ICF panels are manufactured from expanded polystyrene foam (i.e., Styrofoam). Manufacturers use virgin polystyrene, with the polystyrene made from petroleum or natural gas. A blowing agent, usually a hydrofluorocarbon such as HFC-134a (an extremely potent greenhouse gas), is used to “expand” the polystyrene. Like the ICF insulation, the ICCF insulation is made from expanded polystyrene, but its recycled polystyrene not virgin. So, the wall may have started its life as Amazon packaging, but is now helping build your house, significantly reducing the amount of Styrofoam entering the nation’s landfills.
ICCF walls are highly fire resistant as are the concrete cores of the ICF walls. However, the exterior of the ICF wall is simply polystyrene insulation which is highly flammable and releases toxic chemicals when burned. Therefore, both the interior and exterior of the ICF wall require protection from fire hazards.
Big Picture
Homes built using either ICF or ICCF construction are energy efficient with R-Values of 24 to 40+, depending on the thickness of the insulating panels. They are structurally very strong, able to withstand hurricane force winds and powerful earthquakes. They are better at reducing outside road noise compared to traditional houses; less noise pollution equals more pleasant indoor environment. Pests, rodents, and insects won’t attack these walls, and mold won’t grow.
Bottom line, both ICF and ICCF have a great many benefits compared to traditional building methods. However, when looking at the bigger picture of sustainability, I come down on the side of ICCF blocks due to the ICCF using recycled polystyrene instead of virgin material.
For some photos of a home built using ICCF walls, see the Project Gallery page.
Notes:
[1] Cement manufacturing is one of the largest producers of carbon dioxide in the world, creating up to 5% of global emissions of the gas. The production of cement generates nearly one ton of carbon dioxide for every ton of cement manufactured.