If you’ve been specifying spray foam for the past decade, you’ve used HFC-blown closed cell foam. If you’re specifying it today—or will be in the next 12-24 months—you need to understand the industry-wide shift to HFO (hydrofluoroolefin) blowing agents.
This transition is driven by environmental regulation (specifically, global warming potential limits), and it’s not optional. Multiple states have already banned HFC blowing agents, and the rest of the country is following. The good news: HFO foam performs better. The complexity: cost, availability, and compliance timelines vary by region and manufacturer.
Here’s what commercial contractors, spec writers, and building envelope consultants need to know about HFO vs HFC blowing agents in spray foam.
What Are Blowing Agents?
A blowing agent is the chemical that causes liquid polyurethane to expand into foam. When the A-side (polyol) and B-side (isocyanate) are mixed and sprayed, the blowing agent vaporizes, creating millions of tiny gas bubbles that give spray foam its insulating properties.
The type of blowing agent determines:
– R-value: Gas trapped in foam cells has different thermal conductivity
– Expansion ratio: How much the liquid expands (affects yield and density)
– Environmental impact: Global warming potential (GWP) and ozone depletion potential (ODP)
– Regulatory compliance: Some blowing agents are being phased out
Common Blowing Agents in Closed Cell Spray Foam
| Blowing Agent | Type | GWP (100-yr) | R-Value/Inch | Status |
|---|---|---|---|---|
| HFC-245fa | Hydrofluorocarbon | 950-1,030 | R-6.5 | Being phased out |
| HFC-134a | Hydrofluorocarbon | 1,430 | R-6.0 | Phased out (higher GWP) |
| HFO-1233zd(E) | Hydrofluoroolefin | 1 | R-7.0+ | Current standard |
| Water (H₂O) | Physical | 0 | R-3.6-3.8 | Used in open cell foam |
| CO₂ | Physical | 1 | R-3.6-3.8 | Used in some open cell |
HFC (hydrofluorocarbon) blowing agents have high global warming potential—hundreds to thousands of times more potent than CO₂ over a 100-year period.
HFO (hydrofluoroolefin) blowing agents are fourth-generation replacements with GWP <10, functionally equivalent to zero impact.
HFC to HFO Transition: Why It’s Happening
EPA SNAP Rule & AIM Act
The U.S. Environmental Protection Agency’s Significant New Alternatives Policy (SNAP) Rule 20 and the American Innovation and Manufacturing (AIM) Act mandate the phase-down of high-GWP hydrofluorocarbons across multiple sectors, including foam blowing.
Key dates:
– 2021: SNAP Rule 20 prohibited HFC-245fa in new spray foam formulations (delayed by legal challenges)
– 2022: AIM Act codified HFC phase-down into law
– 2025-2027: Most states have fully prohibited HFC-blown foam sales (varies by state)
Bottom line: HFC-blown spray foam is being phased out. Manufacturers have reformulated to HFO.
State-by-State Phase-Out Timelines
Several states have enacted their own HFC bans, often ahead of federal timelines.
| State/Region | HFC Spray Foam Ban Effective Date | Notes |
|---|---|---|
| California | January 1, 2023 | Applies to HFC-245fa and HFC-134a; HFO required |
| Washington | January 1, 2024 | HFC-blown foam prohibited; HFO or water-blown only |
| Oregon | January 1, 2024 | Aligned with Washington |
| New York | January 1, 2025 | Statewide HFC ban for foam blowing |
| Colorado | January 1, 2025 | Phase-out for high-GWP blowing agents |
| Federal (AIM Act) | 2025-2036 (stepdown) | Gradual reduction; functionally HFO-only by 2027-2028 |
If you’re working in CA, WA, OR, NY, or CO, you cannot legally install HFC-blown spray foam. Manufacturers have stopped shipping HFC formulations to these states.
For contractors in other states: even if not yet banned, HFO is becoming the standard. Ordering HFC foam may result in unavailability or higher cost as supply dwindles.
HFO vs HFC: Performance Comparison
R-Value: HFO Wins
HFO-blown closed cell spray foam delivers R-7.0+ per inch (aged), compared to R-6.5 for HFC-blown foam.
Why the improvement?
– HFO-1233zd(E) has lower thermal conductivity than HFC-245fa
– HFO molecules are larger and diffuse more slowly through foam cells
– Long-term R-value retention is better (less aging drift)
Practical impact:
– At 3.5″ thickness: HFO foam = R-24.5; HFC foam = R-22.75
– To hit R-25: HFO requires 3.6″; HFC requires 3.85″
For projects with tight cavity depths (steel studs, CMU cores), that extra R-value per inch matters.
GWP: HFO Crushes HFC
| Blowing Agent | Global Warming Potential (100-yr) |
|---|---|
| HFC-245fa | 950-1,030 |
| HFC-134a | 1,430 |
| HFO-1233zd(E) | <1 |
| CO₂ (reference) | 1 |
HFO blowing agents have GWP <1, essentially zero climate impact from the blowing agent itself. (Note: polyurethane foam production still has embodied carbon from raw materials and energy, but the blowing agent contribution is eliminated.)
For projects pursuing LEED v4/v4.1, NGBS Green, or Passive House certification, low-GWP insulation is often required or earns points. HFO foam qualifies; HFC foam does not.
Cost: HFO Costs Slightly More (For Now)
HFO blowing agents are more expensive to manufacture than HFC, and that cost is passed to contractors.
Typical price delta:
– HFC-blown closed cell foam: $1.20-1.50/board foot (material cost)
– HFO-blown closed cell foam: $1.40-1.70/board foot (material cost)
Difference: +$0.10 to $0.30 per board foot, or roughly 10-20% higher material cost.
For a 10,000 sq ft project at 3″ thickness (30,000 board feet):
– HFC cost: 30,000 bf × $1.35 = $40,500
– HFO cost: 30,000 bf × $1.55 = $46,500
– Delta: +$6,000 (15% higher)
As HFC supply disappears and HFO production scales up, the cost gap is expected to narrow to 5-10% or less by 2026.
Installation & Handling: No Difference
HFO-blown foam installs identically to HFC foam:
– Same spray equipment (plural component rigs)
– Same temperature and humidity windows (60-80°F substrate, <80% RH)
– Same cure times and odor profiles
– Same yield per drum (3,500-4,200 board feet for closed cell)
Applicators who have sprayed HFC foam can switch to HFO with zero retraining.
Which Manufacturers Have Switched to HFO?
All major spray foam manufacturers have introduced HFO-blown formulations. Many have discontinued HFC entirely.
HFO-blown product lines (partial list):
– BASF: Elastospray (HFO)
– Huntsman: HEATLOK HFO, HEATLOK HFO PRO
– Dow: GREAT STUFF PRO (HFO formulations)
– Covestro (formerly Bayer): Bayseal HFO, Bayseal Platinum HFO
– Demilec: HFO-based closed cell systems
– Icynene-Lapolla: ProSeal HFO
If you’re ordering spray foam today, ask your distributor which blowing agent is used. Some suppliers still have HFC stock (especially in non-ban states), but it’s being depleted.
Environmental Compliance & Green Building Certifications
LEED v4 & v4.1 (EA Credit: Enhanced Refrigerant Management)
LEED v4 penalizes high-GWP materials in the building envelope. While the primary focus is HVAC refrigerants, foam blowing agents with GWP >150 can reduce points under EA Credit or Materials & Resources.
HFO foam (GWP <1) earns full compliance. HFC foam (GWP >900) may lose points or require offsets.
For LEED projects, specify HFO-blown spray foam to avoid complications.
NGBS (ICC 700 National Green Building Standard)
NGBS awards points for low-GWP insulation materials under Chapter 7 (Resource Efficiency).
HFO spray foam qualifies for maximum points. HFC foam does not.
Passive House (PHIUS, PHI)
Passive House projects prioritize ultra-low energy consumption but also consider embodied carbon and material environmental impact.
HFO-blown foam is increasingly the default choice for Passive House assemblies that use spray foam (typically as air barrier + cavity insulation in high-performance walls).
California Title 24 & Washington State Energy Code
Both California and Washington have updated energy codes to incentivize or require low-GWP materials.
- California Title 24 (2022): Encourages low-GWP insulation; HFC foam banned statewide as of 2023
- Washington State Energy Code (2021 WSEC): Similar low-GWP preferences
If you’re building in these states, HFO is the only compliant spray foam option.
HFO Spray Foam Supply & Availability
As of 2025, HFO-blown spray foam is widely available from all major distributors. Lead times are comparable to HFC foam (1-3 weeks for bulk orders).
Potential supply issues:
– Regional shortages: Some areas (rural, low-density markets) may see limited HFO stock as distributors clear remaining HFC inventory
– Drum deposits and returns: HFO drums use the same 55-gallon steel drum format; deposit/return programs unchanged
Recommendation: Place orders 2-4 weeks ahead of spray date to ensure HFO product availability and avoid project delays.
Should You Specify HFO or HFC Foam?
Specify HFO if:
– You’re working in CA, WA, OR, NY, CO, or other states with HFC bans (required)
– Project pursues LEED, NGBS, or Passive House certification (required or strongly preferred)
– Client has corporate sustainability goals or ESG reporting requirements
– You want future-proof specs that won’t require reformulation in 12-24 months
Stick with HFC only if:
– You have existing HFC stock and need to use it before expiration (check local regulations first)
– Project is in a state without HFC bans and has zero green building requirements and you need to minimize material cost by 10-15%
Realistically, HFO is the new standard. Specifying HFC in 2025+ is specifying obsolete chemistry.
Product CTA: HFO-Blown Spray Foam Available Now
R-Value Associates stocks HFO-blown closed cell spray foam in 55-gallon drum sets with full technical documentation for code and green building compliance. Our HFO formulations deliver:
– R-7.0+ per inch aged thermal resistance
– GWP <1 for LEED, NGBS, and state compliance
– Class 1 ASTM E84 fire rating
– ICC-ES evaluation reports and test data included
Browse our spray foam product line or contact us for project quotes and spec support.
Frequently Asked Questions
What is HFO blowing agent in spray foam?
HFO (hydrofluoroolefin) is a fourth-generation blowing agent used in closed cell spray foam with ultra-low global warming potential (<1 GWP). The most common HFO blowing agent is HFO-1233zd(E), which replaced HFC-245fa (GWP ~1,000) due to EPA regulations and state HFC bans. HFO-blown spray foam delivers R-7+ per inch, higher than HFC foam (R-6.5), and qualifies for LEED and green building certifications.
What’s the difference between HFC and HFO spray foam?
HFC (hydrofluorocarbon) blowing agents like HFC-245fa have high global warming potential (GWP 950-1,030) and are being phased out by EPA AIM Act and state bans. HFO (hydrofluoroolefin) blowing agents like HFO-1233zd have GWP <1 (near zero climate impact). HFO foam also delivers higher R-value (R-7/inch vs R-6.5) and better long-term thermal performance. Installation, cure time, and cost are nearly identical.
Is HFO spray foam required by code?
Not universally, but California, Washington, Oregon, New York, and Colorado have banned HFC-blown spray foam as of 2023-2025, effectively requiring HFO or water-blown alternatives. Federal EPA AIM Act will phase down HFC supply through 2036, making HFO the de facto industry standard by 2027. Additionally, projects pursuing LEED, NGBS, or Passive House certification require low-GWP insulation, which means HFO spray foam.
Does HFO spray foam cost more than HFC foam?
Yes, but the gap is narrowing. HFO-blown closed cell spray foam currently costs $0.10-0.30 more per board foot (roughly 10-20% higher material cost) due to higher blowing agent production costs. As HFC supply disappears and HFO production scales, prices are expected to converge by 2026-2027. The performance advantage (R-7 vs R-6.5) and regulatory compliance often justify the cost delta.
Which spray foam manufacturers offer HFO blowing agents?
All major manufacturers have transitioned to HFO:
– BASF Elastospray HFO
– Huntsman HEATLOK HFO / HFO PRO
– Dow GREAT STUFF PRO HFO formulations
– Covestro Bayseal HFO
– Demilec HFO closed cell systems
– Icynene-Lapolla ProSeal HFO
Ask your distributor for HFO-specific product data sheets and ICC-ES reports.
Suggested Images:
1. Side-by-side comparison chart: HFC vs HFO spray foam (GWP, R-value, cost, compliance status) — Alt: “HFO vs HFC blowing agent comparison chart for spray foam insulation”
2. Map of United States showing HFC ban effective dates by state (CA, WA, OR, NY, CO highlighted) — Alt: “State-by-state HFC spray foam blowing agent ban timeline map”
3. Spray foam drum label showing HFO-1233zd blowing agent certification and low-GWP logo — Alt: “HFO blowing agent spray foam drum with low GWP environmental certification”
