Rigid mineral wool for exterior continuous insulation: the boards we stock
Rigid mineral wool board is the standard choice for exterior continuous insulation (CI) on high-performance walls. It is non-combustible, vapour-permeable, and holds its R-value for the life of the assembly. Warehoos stocks four rigid mineral wool boards: PowerWool RigiBoard and PowerWool RigiBoard PRO MAX, and ROCKWOOL Comfortboard 80 and Comfortboard 110.
This page sets out what we stock and how to choose between them for a given application. Performance values for each product should be taken from that manufacturer's own current published data sheet.
PowerWool RigiBoard and RigiBoard PRO MAX
The values below are PowerWool's published figures for these products.
| Property | PowerWool RigiBoard | PowerWool RigiBoard PRO MAX |
|---|---|---|
| R-value per inch | R-4.2 | R-4.0 |
| Density | 8 lb/ft³ | 11 lb/ft³ |
| Compressive strength at 10% deformation (ASTM C165) | 616 psf | 755 psf |
| Surface burning characteristics (ASTM E84) | Flame spread 0 / smoke developed 0 | Flame spread 0 / smoke developed 0 |
| Non-combustibility (ASTM E136) | Passes | Passes |
| Water absorption (ASTM C209) | 0.09% by volume | 0.09% by volume |
| Thicknesses stocked | 1.5" / 2" / 3" / 4" | 1.5" / 2" / 2.5" / 3" / 4" |
| Availability | In stock, ships from Warehoos branches in the USA and Canada | In stock, ships from Warehoos branches in the USA and Canada |
| Typical application | Above-grade exterior continuous insulation | Higher-load applications where a denser board is specified |
Data sheets: PowerWool RigiBoard 80 · PowerWool RigiBoard PRO MAX
ROCKWOOL Comfortboard 80 and Comfortboard 110
Comfortboard is manufactured by ROCKWOOL and is the long-established rigid mineral wool board in the North American market. Comfortboard 80 is generally specified for above-grade exterior continuous insulation; Comfortboard 110 is the denser board specified where higher compressive resistance is called for.
Both are tested to the same standards families — ASTM C165 for compressive resistance, ASTM E84 for surface burning characteristics, ASTM E136 for non-combustibility, and ASTM C209 for water absorption.
For R-value per inch, density, compressive strength and available thicknesses, please refer to ROCKWOOL's own current published data sheet for the product and thickness you are specifying. Those are their figures to publish, and they are the ones your code official and design team will want to see.
Choosing between them
The choice is driven by the application, the specification, and what is available for your schedule.
| If your application is… | Consider |
|---|---|
| Standard above-grade exterior continuous insulation, 1.5"–4" | PowerWool RigiBoard or ROCKWOOL Comfortboard 80 |
| An application calling for a denser, higher compressive-strength board | PowerWool RigiBoard PRO MAX or ROCKWOOL Comfortboard 110 — confirm the required compressive value against each manufacturer's data sheet |
| A specification that names a particular manufacturer | Supply the named product. We stock both lines |
| Cavity insulation inside the wall framing rather than continuous insulation outside it | A batt product such as ROCKWOOL Comfortbatt — a different product for a different location in the assembly |
Where a project is schedule-driven, ask us what is physically in stock on the day you order. We carry both lines; lead times on any product move with the market, so we will quote you the current position rather than a general claim.
What rigid mineral wool gives you
These properties are why rigid mineral wool is specified over rigid foam for fire-conscious and moisture-managed assemblies:
- Non-combustible construction, tested to ASTM E136
- Vapour-permeable, so moisture reaching the back of the cladding can dry outward
- Drains water; no organic food source for mould; insects do not nest in it
- R-value stable over the service life — there is no blowing agent to diffuse out
- Cut on site with a serrated blade
- Recyclable
Frequently asked questions
Is PowerWool RigiBoard the same as ROCKWOOL Comfortboard?
No. They are different products from different manufacturers. PowerWool RigiBoard is manufactured by PowerWool Insulation; Comfortboard is manufactured by ROCKWOOL. Compare the two against each manufacturer's current data sheet for the thickness you are specifying.
What is the R-value of PowerWool RigiBoard?
R-4.2 per inch. For Comfortboard, please see ROCKWOOL's current published data sheet.
What is PowerWool RigiBoard's compressive strength?
616 psf at 10% deformation, tested to ASTM C165. PowerWool RigiBoard PRO MAX is published at 755 psf. If your assembly has a minimum compressive requirement, give us the number and we will tell you which of the boards we stock meets it.
Can PowerWool RigiBoard be used below grade or under a slab?
That depends on the load and the detail, and it is a question for your designer. Send us the specified compressive requirement and we will confirm whether a board we stock meets it.
Does PowerWool meet ASTM E136 for non-combustibility?
Yes. PowerWool RigiBoard passes ASTM E136 and is published at flame spread 0 and smoke developed 0 per ASTM E84.
Which board is recommended for IECC climate zone 6 walls?
The 2024 IECC requires continuous insulation in the R-7.5 to R-11.25 range for climate zone 6 wood-framed walls, depending on the compliance path. At R-4.2 per inch, PowerWool RigiBoard reaches R-8.4 at 2" and R-12.6 at 3". Confirm the figure for any other product against its own data sheet, and confirm the compliance path with your code official.
Which is cheaper?
Pricing moves by market, thickness and volume, and both lines are quoted per project. Send us the assembly and the quantity and we will price the options side by side.
Can I use different boards on different walls of the same building?
That is a design decision for whoever is responsible for the assembly. Products differ in thickness, density and compressive performance, so a substitution has to be checked against the specification rather than assumed.
How does mineral wool compare with rigid foam for exterior continuous insulation?
Mineral wool is non-combustible and vapour-permeable, and its R-value does not decline as a blowing agent diffuses out. Rigid foam typically offers a higher R-value per inch. For fire-conscious or moisture-managed assemblies, mineral wool is the usual specification.
Ready to specify?
- Shop PowerWool RigiBoard
- Shop ROCKWOOL Comfortboard 80
- Shop ROCKWOOL Comfortboard 110
Need climate-zone-specific advice? sales@warehoos.com or 1-877-383-2671.
Related guides
- Continuous insulation requirements for climate zone 6 — R-value paths and code-compliant assemblies for IECC zone 6.
- Passive house exterior wall assemblies with mineral wool — envelope build-ups, airtightness layers, and the SKUs that spec into them.
- Order mineral wool insulation online in the USA — ships to all 50 states. Stock, thicknesses, and bulk/contractor pricing.
Disclaimer: The information on this page is taken from each manufacturer's published data and/or open source information online, and is provided for general guidance only. Specifications can change and can vary by product, thickness and market. Always confirm performance values, code compliance and suitability for your assembly against the manufacturer's current data sheet before specifying or ordering. All trademarks are the property of their respective owners, and no manufacturer named on this page has sponsored or endorsed it.