HFO Spray Foam:  What is it and does it matter?

If you have been reading about spray foam you may have seen reference to HFO foam when researching closed cell foam. What is HFO foam? HFO stands for hydrofluoroolefin. Prior to containing HFO, closed cell foam was formulated with HFC, which stands for hydrofluorocarbon. Both HFO and HFC are blowing agents – that is, they are chemicals which cause the foam to react and expand when applied – giving the product the unique characteristics which make it a great insulator.

HFOs break down in the atmosphere far more quickly than HFCs, meaning that HFOs contribute far less to the retention of heat in the atmosphere than HFCs.

As of January 2025, the EPA required all newly manufactured closed cell foam to be made with HFOs. This requirement is not unique to DFW, or Texas, but is a nationwide mandate. Non-HFO foam on the market today was manufactured prior to January of 2025 and, therefore, should be nearly impossible to find. The use and promotion of closed cell spray foam to be “HFO” aligns with the building industry’s commitment to make building materials more environmentally friendly over the long term.

Open cell foam, on the other hand, uses water as its blowing agent, meaning no change from HFCs were required. For this reason, “HFO foam” is a reference only to closed cell foam.