24 by 48 in. module for detail work and lighter lifts
Key features
About R-6.3 at 1.5 in. using R-4.2/in at 75 °F per TDS
8 lb/ft³ rigid stone wool; 0/0 ASTM E84 per manufacturer sheet
Technical specifications
| R-Value | 6.3 |
|---|---|
| Thickness | 1.5 in |
| Width | 24.0 in |
| Length | 48.0 in |
| Coverage | 48.0 sq ft/pack |
| Material | Rigid stone wool (non-structural continuous insulation / CI board) |
| Fire rating | Noncombustible per ASTM E136; Flame Spread 0 / Smoke Developed 0 per ASTM E84 on USA Comfortboard 80 TDS (07-2025). |
| Sound rating | NRC 0.90 and SAA 0.93 at 1.5 in. per ASTM C423 on USA Comfortboard 80 TDS (07-2025). |
| Density | 8 lb/ft³ actual density per ASTM C303 on USA Comfortboard 80 TDS (07-2025). |
| Thermal conductivity | R-4.2 per inch at 75 °F; RSI 0.74 per 25.4 mm at 24 °C per ASTM C518 (C177) on USA TDS. |
| Framing width | Continuous insulation (not stud-spacing specific) |
| Construction type | Wood or steel frame (exterior CI; non-structural) |
| Application area | Exterior CI, rainscreens, perimeter foundation, below slab, and compatible assemblies per current ROCKWOOL / ICC-ES documentation. |
Product details
Full 4x8 sheets maximize coverage per lift, but window legs, foundation steps, and patches often need a lighter module. The 24 by 48 in. format at 1-1/2 in. lets crews handle Comfortboard 80 in tighter zones while building a continuous CI plane when joints are detailed per manufacturer guidance.
Thermal performance uses R-4.2 per inch at 75 °F on the USA data sheet, about R-6.3 for a 1.5 in. layer before framing factors.
Fire reaction language matches the Comfortboard family: noncombustibility paths and 0/0 flame/smoke indices as printed. California State Fire Marshal BML and ICC-ES ESR-3773 appear in ROCKWOOL literature; refresh submittals when listings update.
Acoustics: the TDS assigns NRC 0.90 and SAA 0.93 to the 1.5 in. row.
Vapor permeance versus many foams can help outward drying; still model dew points and liquid water details.
Anchor compliance to https://www.rockwool.com/siteassets/o2-rockwool/documentation/technical-data-sheets/residential/comfortboard-80-non-structural-sheathing-continuous-insulation-techdata.pdf (Issued 07-2025) and https://www.rockwool.com/north-america/products-and-applications/products/comfortboard-80.
Documents & certifications
Technical data sheet
Manufacturer-tested R-value, coverage, fire notes, and handling—use for submittals, RFIs, and field QA.
Download PDF (opens in new tab)Certifications & compliance
ASTM C612 Type IVB, CAN/ULC S702 Type I, ASTM E136 noncombustible, CAN/ULC S114 non-combustible, ASTM E84 / CAN/ULC S102 flame spread 0 / smoke developed 0 (Note 1 Class A per IBC on TDS), ASTM C303 actual density 8 lb/ft³, ASTM C518 R-4.2 per inch at 75 °F (RSI 0.74 per 25.4 mm at 24 °C), ICC-ES ESR-3773 on USA TDS (Issued 07-2025)
Frequently asked questions
What nominal R-value is 1.5 in. Comfortboard 80?
What nominal R-value is 1.5 in. Comfortboard 80?
Multiply thickness by R-4.2 per inch at 75 °F: about R-6.3 for 1.5 in. for the board layer alone, per the USA TDS.
Is this board structural?
Is this board structural?
No. Comfortboard 80 is non-structural continuous insulation. Provide structural sheathing and engineered attachment separately.
Why choose 24x48 instead of 4x8?
Why choose 24x48 instead of 4x8?
Smaller sheets reduce weight per lift and simplify cuts around openings; verify bundle packaging on the master label.
Does high permeance eliminate a WRB?
Does high permeance eliminate a WRB?
No. The board does not replace a water-resistive barrier, flashings, and drainage detailing required by code.