Mineral-wool ETICS
The mineral version of the external insulation system: rock-wool boards bonded and anchored to the wall, base-coated with mesh and finished with render. Compared with EPS, rock wool is non-combustible (Euroclass A1/A2) and vapour-open: the system «breathes» and resists fire, which is why it is the typical choice for tall buildings and fire compartments, where the façade's reaction to fire is decisive.
Technical section of the system, from inside (left) to outside (right).
The mineral version of the external insulation system: rock-wool boards bonded and anchored to the wall, base-coated with mesh and finished with render. Compared with EPS, rock wool is non-combustible (Euroclass A1/A2) and vapour-open: the system «breathes» and resists fire, which is why it is the typical choice for tall buildings and fire compartments, where the façade's reaction to fire is decisive.
Mineral-wool ETICS is an external insulation system in which the synthetic insulant is replaced by mineral rock-fibre boards. The logic is the same as the classic system — bonding, anchoring, mesh-reinforced base coat, finish — but two key properties of the material change: the reaction to fire and the vapour permeability.
Rock wool is a mineral: it does not burn and does not spread flame (Euroclass A1/A2). On a tall building this is decisive, because a combustible façade can turn a single-floor fire into a fire of the whole envelope. This is why mineral systems, or mineral fire-barrier bands, are required or recommended above certain heights and in fire-regulated activities.
Unlike EPS, rock wool lets vapour through: the system is «breathable». Moisture migrating from inside to outside is not trapped but dries out, reducing the risk of interstitial condensation and favouring healthier walls, especially on historic buildings and massive masonry that need to release moisture.
Rock wool is denser and heavier than EPS: it improves the façade's acoustic insulation and adds inertia, but it needs anchors and adhesives suited to the weight and careful laying that does not compress the board. Reinforced base coat, finish and accessories (corner beads, drips, starter profiles) follow the same rules as the classic system; the finish must stay vapour-open (silicate or siloxane renders and paints) so the advantage is not lost.
Why it works
Breathable and non-combustibleTwo mineral qualities change how the system behaves. Rock fibre is vapour-open: the moisture leaving the wall passes through the insulation and dries, instead of condensing trapped as can happen with impervious layers. And it is non-combustible (Euroclass A1/A2): it neither feeds the flame nor spreads it along the façade, the reason the mineral is chosen on tall buildings and for fire compartments. Its mass also improves the acoustic insulation.
Fire safety of the insulant
Comparison · insulantsNodal details
Critical junctions · sectionsAt the base an aluminium starter profile carries the first row of boards and sets the line; a drip throws the water clear, and the plinth zone is detached from the ground so rising damp and splashing do not soak the mineral wool.
- Backing wall
- Rock-wool board
- Reinforced base coat + render
- Aluminium starter profile
- Drip edge
- Plinth zone
Beyond the adhesive, mushroom anchors fix the heavier mineral boards to the wall; the base coat is reinforced with a glass-fibre mesh embedded in its outer third, then the breathable finish render is applied.
- Backing wall
- Adhesive
- Rock-wool board
- Mushroom anchor
- Reinforced base coat + mesh
- Finish render
Installation controls
Specification · checklist01 · Substrate
02 · Bonding & boards
03 · Anchoring
04 · Reinforced base coat
05 · Breathable finish
Recurring defects
Diagnostics · siteComponent materials
The network · materialsReference regulations
2 norms- D.P.R. 380/2001Consolidated Building Act (Testo Unico Edilizia)In force
- UNI EN 13501-1:2019Fire classification of construction products and building elements - Part 1: Reaction to fireIn force
Informational links to the regulatory framework. Always verify the current text on the official source.