Selection of insulated panels
PIR or mineral wool: what to compare in a sandwich panel
In brief
PIR and mineral wool are not substitutes chosen on price alone. The choice starts with fire, thermal and structural requirements. At the same thickness, panels can differ in mass and U-value. It is worth comparing full configurations and checking how much space the finished enclosure will take up. First establish the project requirements, especially those related to fire. The reaction to fire of the material and the fire resistance of the partition are different issues. The classification of the complete panel covers a specific construction. Conclusions should not be drawn from the core name alone.
Which requirement can immediately narrow the choice?
Example mineral wool panels have reaction class A2-s1,d0, while selected steel PIR panels have B-s1,d0. These designations are not equivalent. They also do not on their own determine the required EI or REI class of the wall or roof. The specific assembly, installation direction and supports must be checked.
What does the thermal comparison look like at 100 mm?
In an example family of steel PIR wall panels 100 mm thick, the Uc value is 0.22 W/(m²·K). In one family of mineral wool panels 100 mm thick, it is 0.41. These are data for two specific configurations. They do not describe all products and should not be mixed with roof data.
If the aim is similar thermal insulation, the comparison may require different thicknesses. This matters at reveals, roof edges and usable dimensions. A comparison of “100 mm versus 100 mm” is clear, but does not always correspond to the actual design task.
How does mass affect a small construction site?
For the given example, the PIR panel weighs approximately 12.3 kg/m², and the mineral wool panel approximately 19.8 kg/m². The values depend among other things on the facings and the core variant. For a 1 × 6 m element, this gives approximately 73.8 and 118.8 kg respectively. This is the mass of the panels alone in the adopted example.
The difference affects the choice of equipment and the organisation of lifting. A long panel nevertheless requires appropriate handling regardless of its mass. On a narrow plot, the unloading area, the carrying route and the space for setting up the equipment must be planned. A lighter element does not mean it can be installed manually at will.
If the module width is 1.1 m instead of 1.0 m, an element of the same length has a larger area and mass. The transport set should therefore be calculated from the actual covering dimensions, in accordance with the basis of the stated unit mass.
Does mineral wool always mean better acoustic insulation?
The properties of the loose material should not be equated with the complete panel. Full steel facings change the acoustic behaviour. Sound transmission and sound absorption within the interior are assessed separately. One parameter does not replace the other.
Compare the results for specific products, as well as doors and openings in the enclosure. Leaky connections can limit the effect. If reverberation is the problem, an additional acoustic element may be needed. The choice of wall core alone does not guarantee a quiet hall.
How do the differences affect the structure and fixing?
Each variant is selected from the appropriate load table. The span depends on the core, thickness, facings and support arrangement. The result for a PIR panel cannot be transferred to mineral wool or vice versa. Greater thickness alone does not prove compliance.
Check the self-weight and wind load, and on the roof also snow. The fixings must match the panel and the structure. Large windows and gates require designed framing. If you change the core after the frame has been built, the selection must be verified again.
How should behaviour in damp conditions be compared?
Both solutions need correct facings, edges and seals. The choice should not be based on the claim that one core will forgive any leak. Water entering unforeseen places can impair the durability and working conditions of the enclosure.
The properties of the coating on the room side are also important. Moisture and aggressive chemicals affect the surface and accessories, not only the core. For special use, the environment and cleaning method must be described. The material should be selected for the whole situation.
How can a decision be reached without ranking winners?
Prepare two variants that meet the same objective. Record the thickness, mass, fire requirements, construction and installation cost. Add the impact on opening dimensions and interior space. This shows the difference between complete solutions, not just the price per metre of panel.
Specify the exact parameters in the order. A change in sheet thickness or core type may require re-verification. The right choice is the one that meets the building requirements and can be installed correctly. There is no single answer suitable for every hall, garage and partition.
Questions before ordering
Can the mineral wool be changed to PIR without changing the design?
Such a possibility should not be assumed. Fire, load-bearing capacity, thermal performance, acoustics and details must be checked. Matching thickness alone is not enough.
Does a greater panel mass automatically mean greater load-bearing capacity?
No. The load-bearing capacity results from the construction of the entire panel and its behaviour on the supports. The correct table for the specific configuration is required.
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