Mineral Wool Sandwich Panel Selection Guide & FAQ
Mineral wool sandwich panels are specified when fire and acoustic performance matter as much as insulation. The non-combustible stone-wool core gives the panel a fire reaction class that foam cores cannot match, while its dense fibrous structure absorbs sound. The guide below covers the decisions engineers and architects make when choosing mineral wool panels for walls, roofs, and fire-separated buildings.
Pro Tip: Lead with the Fire and Acoustic Requirement
Mineral wool costs more in thickness for the same U-value than PU, so it is chosen for a reason: fire resistance, sound reduction, or both. Establish the required EN 13501-1 class and the target sound reduction first, then size the core for thermal performance, rather than optimizing insulation alone and finding the panel fails the fire or acoustic check.
1. What fire performance does the mineral wool core provide?
The stone-wool core is non-combustible and carries a reaction-to-fire classification of A2-s1,d0 under EN 13501-1, meaning it contributes negligibly to fire, produces little smoke, and no flaming droplets. Complete panel assemblies can achieve fire-resistance ratings up to EI 240 depending on core thickness and configuration. This is why mineral wool panels are the default for fire walls, compartmentation, and buildings with strict fire codes.
| Property |
Mineral Wool Panel |
| Reaction to fire |
A2-s1,d0 (non-combustible) |
| Fire resistance (assembly) |
Up to EI 240 by thickness |
| Thermal conductivity |
~0.043 W/(m·K) |
| Sound reduction |
> 30 dB at 50 mm, rising with depth |
2. How effective is the acoustic insulation?
The dense, open fibrous structure of mineral wool converts sound energy into heat as the wave passes through it, which gives the panel strong airborne sound insulation. A 50 mm core already exceeds 30 dB of sound reduction, and the figure rises with core thickness. This makes the panel well suited to workshops, plant rooms, sports and concert halls, and any building where separating noisy and quiet spaces is a design goal.
3. How does thermal performance compare with foam cores?
Mineral wool’s thermal conductivity of about 0.043 W/(m·K) is roughly double that of PU at 0.022–0.024 W/(m·K), so reaching the same U-value requires a thicker core. This is the accepted trade-off: where fire and acoustic performance govern, the extra thickness is worthwhile; where the priority is maximum insulation in the thinnest build-up, PU or PIR is the more efficient choice. Many projects use both, mineral wool for fire walls and foam for the general envelope.
Mixed-specification strategy
Rather than choose one core for the whole building, specify mineral wool where the code demands fire resistance or sound separation and a foam core elsewhere. This meets every performance requirement at the lowest overall cost and thickness.
4. What structural and span characteristics should I expect?
The mineral wool core is supplied at densities typically of 110–120 kg/m³, which gives the panel good rigidity and load-bearing capacity for wall and roof applications. Span between supports depends on core thickness, skin gauge, and the governing load, and is confirmed by a deflection check. Steel cladding from 0.3 mm to 0.8 mm lets the facing be matched to the structural demand and the exposure.
5. Where are mineral wool panels the right choice?
The panel earns its place wherever fire or sound is a governing requirement: fire walls and compartmentation, industrial and commercial buildings with strict fire codes, noisy plant and process areas, and public buildings such as sports and concert halls. For external walls, internal partitions, ceilings, and roofs alike, the combination of non-combustibility, acoustic absorption, and adequate insulation in a single assembly is difficult to beat.
Frequently Asked Questions
What fire rating do mineral wool sandwich panels achieve?
The mineral wool core is non-combustible, with a reaction-to-fire classification of A2-s1,d0 under EN 13501-1, and panel assemblies can reach fire-resistance ratings up to EI 240 depending on thickness and configuration. This makes them the standard choice where fire separation is a governing requirement.
How good is the acoustic insulation?
The dense, fibrous core absorbs sound effectively, giving airborne sound reduction that exceeds 30 dB at 50 mm thickness and rises with core depth. This suits workshops, plant rooms, concert and sports halls, and any building where noise separation between spaces matters.
How does the thermal performance compare with PU panels?
Mineral wool has a higher thermal conductivity, around 0.043 W/(m·K), than PU at roughly 0.022–0.024 W/(m·K), so a thicker core is needed for the same U-value. The trade-off is accepted where fire and acoustic performance are the priority; where pure insulation in a thin build-up is the goal, PU or PIR is more efficient.
What thicknesses and sizes are available?
Core thicknesses run from 50 mm to 300 mm, with mineral wool density typically 110–120 kg/m³. Panel lengths range from 2500 mm to 15000 mm, effective widths of 1000 mm or 1100 mm, and steel cladding from 0.3 mm to 0.8 mm, allowing the specification to be matched to the structural and thermal demand.
