StoTherm Mineral Insulation
For architects and specifiers working on high-rise, public, or fire-rating-critical projects, StoTherm Mineral is a non-combustible external wall insulation system for solid masonry construction — built around a mineral-wool insulation core rather than the EPS panels used across the rest of the StoTherm range.
This page explains what StoTherm Mineral insulation is, how it differs from Sto's EPS-based masonry systems, and when fire performance makes it the right specification choice.
Why Fire Rating Drives This System
Fire protection becomes an increasingly important consideration as building height and public occupancy increase. Masonry external wall insulation systems used on high-rise or public buildings are recommended to consist of non-combustible components — a requirement that EPS-based insulation, however well it performs thermally, simply doesn't meet on its own. StoTherm Mineral was added to the StoTherm family specifically to close that gap, without giving up the thermal, acoustic, and moisture-management performance the rest of the range is built on.
Who This Matters For
This system is most relevant where fire rating is a genuine specification driver — high-rise residential and commercial buildings, public buildings, and any project where non-combustible facade components are recommended or required by the applicable building classification. It's also a fit for projects where acoustic performance is a secondary but real consideration alongside thermal insulation, since mineral wool's density gives it acoustic properties that EPS-based systems don't share. For masonry projects without a specific non-combustibility requirement, Sto's StoTherm Armat Masonry or StoTherm Vario systems remain the more straightforward and typically more cost-effective choice.
What Makes the Mineral-Wool Core Different
At the core of the system is the StoTherm Mineral Insulation Board: 80mm insulation boards made from stone mineral-wool. The manufacturing process starts with molten rock, similar in composition to lava, which is spun into fibres as it re-solidifies — a process that produces a non-combustible slab, subsequently cut into boards. The result is a mineral-wool insulation layer with genuinely different properties to EPS foam: non-combustible by nature, highly water-tight while remaining permeable to water vapour and CO2, and with acoustic performance that EPS-based systems don't offer.
The StoTherm Mineral Insulation Board — 80mm stone mineral-wool, being installed on a masonry substrate.
How the System Works
The layered system follows the same underlying logic as Sto's other masonry systems. Solid masonry substrate — concrete block, pre-cast, brick, or in-situ concrete — is bonded with a Gluecoat Mortar adhesive, followed by the 80mm StoTherm Mineral Board, fixed with a StoTherm Masonry Anchor, drilled, installed, countersunk, and capped to avoid thermal bridging at the fixing point. A StoLevell Novo mineral basecoat follows, then the StoArmat Render reinforcement layer — organic, cement-free, weather-resistant, with crack resistance up to six times higher than standard cement-based plasters — reinforced with Sto glass fibre mesh, finished with a coloured Stolit Render and StoColor facade paint.
The StoTherm Mineral External Wall Insulation System's layers — adhesive mortar, mineral-wool board, countersunk anchor, base coat, reinforcement render, mesh, and finish.
This isn't simply an EPS system with a different insulation material swapped in. The mineral-wool core changes what the system can genuinely claim: non-combustibility for fire resistance, high insulation values comparable to the rest of the StoTherm range, moisture management through high vapour permeability combined with water tightness, and acoustic performance that comes from the density and structure of mineral wool itself rather than from a separate acoustic system. It's suited to refurbishment and new-build projects up to high-rise level, which is precisely the segment where non-combustible facade components matter most.
Sto's StoArmat Render reinforcement layer — the same organic, cement-free render used across the StoTherm family — still delivers its crack resistance and impact performance within the Mineral system. The fire-rating benefit comes specifically from the insulation core; the render layer's performance characteristics are unchanged.
Built for Demanding Applications
Beyond fire resistance, StoTherm Mineral brings a combination of properties that's genuinely distinct within the StoTherm range: high water-tightness while remaining permeable to CO2 and water vapour, so the wall assembly can manage moisture rather than trap it; resistance to mechanical and seismic stress; and suitability for refurbishment as well as new-build projects up to high-rise level. Combined with the StoArmat render layer's crack resistance, it's a system engineered for demanding applications rather than a fire-rated compromise on performance elsewhere.
Warranty and Installation
StoTherm Mineral carries a 20-year Sto Warranty with StoService Assurance, matching the coverage on Sto's other masonry systems. Installation is carried out exclusively by Sto-registered contractors, ensuring the system is applied to specification and the warranty remains valid.
Specifying StoTherm Mineral follows the same process as any Sto system: an initial consultation to discuss substrate, fire-rating requirements, and building classification; confirmation that a non-combustible system is the right fit for the project's regulatory context; specification support including plan review and Sto's CAD/PDF detail library; installation exclusively by Sto-registered contractors; and ongoing StoService Assurance across the warranty period.
Proven in Practice
StoTherm Mineral and the broader mineral-wool insulation approach it's built on have been applied internationally on projects where non-combustibility and design ambition both mattered. A residential house on The Crescent in Wiltshire, designed by Ken Shuttleworth of Sir Norman Foster's practice, and Schlump ONE in Hamburg, designed by J. Mayer H. Architects, both demonstrate the system's ability to support genuinely ambitious architectural design without compromising on fire performance.
Frequently Asked Questions
What makes StoTherm Mineral different from Sto's other masonry insulation systems?
The insulation core. StoTherm Mineral uses 80mm mineral-wool boards rather than the EPS panels used in StoTherm Armat Masonry and StoTherm Vario, giving it non-combustibility for fire resistance alongside acoustic properties that EPS-based systems don't offer. The render, mesh, and finish layers follow the same underlying system logic as the rest of the StoTherm range.
Is StoTherm Mineral suitable for high-rise buildings?
Yes — it's specifically positioned for refurbishment and new-build projects up to high-rise level, where non-combustible facade components are recommended or required.
What substrates does StoTherm Mineral cover?
Solid masonry substrates, including concrete block, pre-cast concrete, brick, and in-situ concrete — the same substrate range as Sto's other masonry systems.
Does StoTherm Mineral still deliver StoArmat's crack resistance?
Yes. The system uses the same StoArmat Render reinforcement layer as Sto's other masonry systems, delivering the same crack resistance performance — the mineral-wool core changes the insulation and fire-rating characteristics, not the render layer.
Who installs StoTherm Mineral?
Installation is carried out exclusively by Sto-registered contractors, keeping the warranty valid and ensuring the system is applied to specification.
Last updated September 2026
