2 in. thickness in 24x48 in. sheets for manageable lifts
Key features
About R-8.4 insulation layer using R-4.2/in at 75 °F per TDS
8 lb/ft³ rigid stone wool with documented fire reaction metrics
Technical specifications
| R-Value | 8.4 |
|---|---|
| Thickness | 2.0 in |
| Width | 24.0 in |
| Length | 48.0 in |
| Coverage | 40.0 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 0.95 and SAA 0.97 at 2 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 behind claddings and other approved uses per ICC-ES and manufacturer literature. |
Product details
Mid-thickness CI balances cladding standoff, cost, and whole-wall R-value. A 2 in. Comfortboard 80 layer delivers about R-8.4 for the board using R-4.2 per inch at 75 °F, in a module many crews can stage without full 4x8 handling everywhere.
Add cavity insulation, framing factor, and interior or exterior continuous layers in your energy model.
Attachment routes through engineered furring or long-screw solutions; the TDS cites ASTM C165 compressive data for discussions with cladding designers.
Reaction to fire and fungi resistance statements support durability narratives but do not replace WRBs or structural design.
Acoustics: NRC 0.95 and SAA 0.97 for the 2 in. row in the TDS table.
Pair field work with https://www.rockwool.com/siteassets/o2-rockwool/documentation/technical-data-sheets/residential/comfortboard-80-non-structural-sheathing-continuous-insulation-techdata.pdf and current ROCKWOOL installation guides.
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
Is 2 in. Comfortboard enough for my climate?
Is 2 in. Comfortboard enough for my climate?
Compare nominal layer R from R-4.2/in to your modeled assembly and IECC path; CI thickness alone rarely tells the whole compliance story.
24x48 versus 4x8 at 2 in.?
24x48 versus 4x8 at 2 in.?
Same thickness and product family; choose the module that matches crew ergonomics and opening layout. Confirm pack square footage on the label.
Do I need furring?
Do I need furring?
Many claddings require drained and back-ventilated cavities; furring depth and attachment depend on cladding type and wind load.
Can I rip boards on site?
Can I rip boards on site?
Cutting mineral wool boards with appropriate tools is common; use PPE and keep factory edges true where air barrier tapes land.