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PowerWool RigiBoard vs Rockwool Comfortboard

PowerWool RigiBoard vs Rockwool Comfortboard — Mineral Wool Insulation Comparison

PowerWool RigiBoard and Rockwool Comfortboard are the two most-specified rigid mineral wool boards for exterior continuous insulation in North America. Both are non-combustible, semi-rigid, and deliver R-4 to R-4.3 per inch. The choice between them comes down to four factors: compressive strength, availability, price, and the specific application (above-grade wall vs below-grade foundation vs roof).

This page compares the four rigid mineral wool boards we stock — PowerWool RigiBoard, PowerWool RigiBoard PRO MAX (both Warehoos exclusive), Rockwool Comfortboard 80, and Rockwool Comfortboard 110 — head-to-head.

At-a-glance comparison

Property PowerWool RigiBoard PowerWool ProMax Comfortboard 80 Comfortboard 110
R-value per inch R-4.0 R-4.0 R-4.2 R-4.3
Density 8 lb/ft³ 11 lb/ft³ 8 lb/ft³ 11 lb/ft³
Compressive strength @ 10% deformation (ASTM C165) 616 psf >876 psf (~50% > Comfortboard 110) 439 psf 584 psf
Flame Spread (ASTM E84) 0 0 0 0
Smoke Developed (ASTM E84) 0 0 0 0
Non-combustible (ASTM E136) ✓ ✓ ✓ ✓
Water absorption (ASTM C1763) <1% volume <1% volume <1% volume <1% volume
Common thicknesses 1.5" / 2" / 3" / 4" 1.5" / 2" / 2.5" / 3" / 4" 1.25"–3" 1.5" / 2" / 3"
Typical lead time (Warehoos) In stock In stock Often in stock; can extend Often in stock; can extend
Best application Above-grade exterior CI High-load / below-grade alt to Comfortboard 110 Above-grade exterior CI Below-grade / high-load

Where PowerWool wins

1. Compressive strength. PowerWool RigiBoard handles ~40% more compressive load than Comfortboard 80 (616 psf vs 439 psf at 10% deformation, ASTM C165). For wall assemblies where fasteners or furring strips need to seat firmly without crushing the insulation, this matters. PowerWool ProMax goes further — >876 psf, exceeding even Comfortboard 110's 584 psf — for the highest-load applications.

2. Availability. Rockwool Comfortboard has faced extended lead times in recent supply cycles (we've seen 8–12 week quotes from US distributors). PowerWool ships from Warehoos branches across USA and Canada in 1 business day to 2–3 day transit, in stock.

3. ProMax matches Comfortboard 110 on density at higher compressive strength. Both are 11 lb/ft³ rigid boards for high-load and below-grade applications. ProMax delivers ~50% more compressive strength than Comfortboard 110 (>876 psf vs 584 psf) at the same density — a direct alternative when Rockwool isn't available.

4. Price. PowerWool RigiBoard is consistently below Comfortboard 80 on a per-board-foot basis. (Current pricing on the PowerWool PDP → and PowerWool ProMax PDP →.)

Where Rockwool Comfortboard wins

1. Brand recognition and spec familiarity. Comfortboard is the incumbent. If your jurisdiction, code official, or design team is already familiar with Rockwool, the spec path is shorter.

2. Marginally higher R-value per inch. Comfortboard 80 at R-4.2 / inch vs PowerWool RigiBoard at R-4.0 / inch. Small difference; meaningful only at the highest CI thicknesses (4"+ assemblies).

3. Widest thickness range on the standard product. Comfortboard 80 is available in 1.25", 1.5", 2", 2.5", and 3". PowerWool ProMax matches this range; PowerWool RigiBoard has a slightly narrower range (1.5"–4").

Decision rubric

Use this to choose between the four:

If your application is... Choose
Standard above-grade exterior continuous insulation, 1.5"–4" thick, you want stock availability and the best $/board-foot PowerWool RigiBoard
High-load, below-grade, under-slab, or any application requiring ≥600 psf compressive strength PowerWool ProMax (>876 psf)
Above-grade exterior CI, brand-spec mandates Rockwool, lead time is acceptable Comfortboard 80
High-load Rockwool-spec project where ProMax isn't acceptable Comfortboard 110
Cavity insulation inside the wall framing (not continuous insulation outside) Comfortbatt (different product — see Comfortbatt →)

Both products: what they share

Don't lose sight of what's the same about both. Either choice gets you: - Non-combustible, FSI 0 / SDI 0 per ASTM E84, ASTM E136 verified - Vapor-permeable — moisture that gets behind the cladding can dry out - Drains water; insects don't nest in it; mold has no organic food source - Stable R-value for the service life (no foam-blowing-agent diffusion) - Manageable on a jobsite — can be hand-cut with a serrated knife - 100% recyclable

This is why mineral wool keeps winning spec wars against rigid foam: the product properties match what high-performance walls actually need.

Real-world projects using each

(Section to be filled in with case studies as available — leave a placeholder for now.)

Frequently asked questions

Q: Is PowerWool RigiBoard the same as Rockwool Comfortboard?

A: No. They're both rigid mineral wool boards with similar performance, but they're different products from different manufacturers. PowerWool RigiBoard is exclusive to Warehoos. Rockwool Comfortboard is manufactured by Rockwool North America. Property differences are summarized in the at-a-glance table above.

Q: Which has a higher R-value, PowerWool RigiBoard or Comfortboard 80?

A: PowerWool RigiBoard is R-4.0 per inch. Comfortboard 80 is R-4.2 per inch. The R-value difference is small. The bigger differentiators are compressive strength (PowerWool higher), stock availability (PowerWool more consistent), and price.

Q: Which is more compression resistant, PowerWool or Comfortboard?

A: PowerWool RigiBoard handles approximately 40% more compressive load than Comfortboard 80 at 10% deformation (616 psf vs 439 psf, ASTM C165). For high-load applications, PowerWool ProMax exceeds both (>876 psf) and Comfortboard 110 falls in between (584 psf).

Q: Can PowerWool RigiBoard be used below-grade or under a slab?

A: For typical above-grade exterior continuous insulation, yes. For below-grade foundation walls or under-slab applications where high compressive strength is required, PowerWool ProMax (>876 psf, 11 lb/ft³) is the direct alternative to Rockwool Comfortboard 110 — same density class, higher compressive strength, in stock at Warehoos.

Q: Is PowerWool actually in stock when Comfortboard isn't?

A: That has been the pattern through 2025–2026 supply cycles. PowerWool ships from Warehoos branches across USA and Canada with 1-business-day pick + 2–3 day transit. Comfortboard availability fluctuates with Rockwool's North American production cycle.

Q: Does PowerWool meet ASTM E136 for non-combustibility?

A: Yes. PowerWool RigiBoard is non-combustible per ASTM E136 with FSI 0 and SDI 0 per ASTM E84 — same fire performance class as Comfortboard.

Q: Which is recommended for IECC climate zone 6 walls?

A: 2024 IECC requires R-7.5 to R-11.25 continuous insulation in climate zone 6 wood-framed walls. Both PowerWool RigiBoard at 2"–3" (R-8 to R-12) and Comfortboard 80 at 2"–3" (R-8.4 to R-12.6) meet the requirement. Comfortboard 80 has marginally higher R per inch; PowerWool wins on compressive strength and stock availability.

Q: Is there a price difference between PowerWool and Comfortboard?

A: PowerWool is typically lower-priced per board-foot for equivalent R-value. Live pricing on the PowerWool PDP and Comfortboard 80 PDP.

Q: Can I mix and match — some PowerWool on one wall, Comfortboard on another?

A: Yes. The two products are interchangeable from a building-science perspective. Both achieve the same continuous-insulation function with the same fire and moisture properties. Some projects use whichever is in stock at the time of order.

Q: How does mineral wool compare to rigid foam for exterior continuous insulation?

A: Mineral wool drains, dries, and resists fire — rigid foam does none of these well. Foam has slightly higher R-value per inch but degrades over time. For fire-conscious or moisture-managed assemblies, mineral wool (either PowerWool or Comfortboard) is the safer specification.

Ready to spec mineral wool for your project?