Mineral-wool sandwich panels: advantages, limitations and comparison with PIR

Mineral-wool panels include products with reaction-to-fire class A2-s1,d0. This is a property of a specified product and must be confirmed when buying. It is not the same as the duration of a wall’s fire resistance. The required EI class depends on the complete solution, including the panel and how it is installed.

Mineral wool may be justified in a design with demanding fire requirements. Supports, span and fixings still need checking, as do service penetrations. Placing a non-combustible core between two steel sheets does not remove the need for the other details. A declared property applies only when the installed assembly falls within the documentation’s scope.

Consider two example products: a mineral-wool wall panel with Rw 33 dB and a PIR panel with Rw 26 dB. This shows an advantage for the wool panel in that particular pair. It does not mean every mineral-wool panel has the same advantage over every PIR panel. Read the values for the thickness and construction being ordered.

In a completed building, gates, doors, joints and sound transmitted by other paths also matter. Rw does not describe room reverberation. If machinery noise is the problem, establish its characteristics before choosing the wall. Otherwise money may improve a property that does not address the main source of disturbance.

An example 100 mm mineral-wool panel has U = 0.39 W/(m²K), while the compared 100 mm PIR panel has U = 0.22 W/(m²K). A lower value means less heat transmission under otherwise equal conditions. In this pair, PIR insulates better at the same thickness. These figures are not fixed properties of every product in either material group.

Where the design sets a thermal target, compare versions that meet it rather than just two prices for 100 mm panels. Thicker wool changes weight, flashing widths and fastener lengths. What looks like a simple material comparison becomes an assessment of the whole wall solution.

In the example, the 100 mm mineral-wool panel weighs 18.1 kg/m² and the 100 mm PIR panel 12.3 kg/m², both with 0.5/0.5 mm facings. Across 100 m², the difference is 580 kg. This calculation applies only to those two variants and excludes the structure, flashings and fixings. Different steel facings or core versions change the result.

Greater weight does not rule out mineral wool, but it must be included in design and work planning. The weight of each panel matters, not just the total delivery. Lifting long panels requires planning. Unloading instructions specify appropriate support and protection for facings and edges.

Mineral-wool panels need properly finished ends. Water must not reach the core through damaged joints or flashings. Tightness remains important for PIR panels too. No core material excuses incorrect installation. The manufacturer’s details and the cladding design provide the basis.

Compare documentation availability, coatings and maintenance requirements when buying. Do not assume in advance that mineral wool is always more expensive: price depends on the model, order and delivery scope. A reasoned design may use wool in one part of a building and another system elsewhere. That choice must follow the design rather than an arbitrary substitution.

Separate purchase costs from operating costs. The first include panels, transport, lifting and accessories. The second include heat losses and surface maintenance. Even a simple comparison needs common assumptions: the same wall area does not necessarily perform the same function.

Do not calculate savings from a better U-value without temperatures and heating periods. An unheated warehouse differs from a hall heated throughout the year. A fire-performance advantage likewise has value in relation to specific requirements; it cannot be assigned a universal price per square metre.

Ask for two complete cladding alternatives, each meeting the project’s requirements. Then compare totals and the work involved. This is a fairer assessment than ranking materials solely by the price of a panel at an arbitrarily selected thickness.

That cannot be generalised. Compare results for the exact panels and account for the whole wall assembly.

No. Fire performance, supports, fasteners, exposure conditions and installation still need to be checked.