ICCF
A proven way to build, made from waste.
Insulated composite concrete forms explained: the system, the comparison, the testing, and the questions builders ask.
What is ICCF?
Insulated composite concrete forms, explained.
An ICCF block is a hollow form made from recycled EPS foam ground into beads and bound with Portland cement. Crews stack the blocks, set rebar in the cores and fill them with concrete. The blocks stay in place as the insulation and the finish surface.
It is not a new idea. Cement-and-foam composite blocks have been made in North America for decades, by companies such as Rastra and EF Block, and today several manufacturers make blocks that are 85% or more recycled foam.
| ICCF (Common Block) | Foam ICF | Concrete block (CMU) | Wood frame | |
|---|---|---|---|---|
| Form material | Recycled EPS + cement | Virgin EPS foam panels | Concrete | Lumber + sheathing |
| Wall structure | Concrete grid in the cores | Solid concrete slab | Grouted cells | Studs |
| Burns? | No, cement-bonded | Foam needs a thermal barrier | No | Yes |
| Built-in insulation | Yes, the block itself | Yes, foam both sides | No, added separately | Batts in cavities |
| Finish | Stucco / plaster direct | Needs fastening strips | Stucco or furring | Siding / drywall |
| Rot, mold, termites | Resistant | Foam can host termites | Resistant | Vulnerable |
| Recycled content | High (waste foam) | Low | Low | Varies |
Built to be tested, not just claimed.
ICCF is already recognised by U.S. building codes and testing labs. Another manufacturer's ICCF forms carry an ICC-ES evaluation report under the 2021 and 2024 International Residential Code, and a load-bearing ICCF wall has passed a 4-hour ASTM E119 fire test at Intertek. We will put Common Block through the same tests before it goes on a job site:
- ASTM E119Fire resistance of the finished, load-bearing wall
- ASTM E84Surface burning and smoke development
- ASTM C1363Thermal performance of the wall assembly
- ICC-ESCode evaluation report for builders and inspectors
Questions
What builders ask us.
Is the foam a fire risk?
Each foam bead is coated in cement, so the block does not burn the way foam panels do. Cement-bonded forms are inherently fire resistant, and composite blocks of this type are commonly rated above four hours. The wall is still finished with stucco or plaster, as codes require.
What R-value will the wall have?
It depends on block thickness and the concrete core. Published figures for cement-EPS blocks range widely, and some count the thermal mass of the concrete. We are designing for R-40 performance and will publish tested numbers (ASTM C1363), not estimates.
Does it use more cement than a normal wall?
The concrete only fills the cores, forming a grid instead of a solid slab, which is where the roughly 30% concrete saving comes from. The blocks themselves contain cement too, so we are working on mix designs with lower-carbon binders.
Can my crew install it?
Yes. Blocks dry-stack without mortar, cut with ordinary saws, and take rebar and a concrete pour like any ICF wall. Pilot builders will get on-site support for their first walls.
Where does the foam come from?
Clean packaging foam from Nashville retailers and appliance deliveries, construction offcuts, and the city's EPS collection at the East Convenience Center. We do not use contaminated or food-service foam.