EPS, PIR or mineral wool for a commercial building: how do you choose?

Before comparing prices, establish any fire, acoustic or mechanical requirements that rule out an assembly. An insulation board with low thermal conductivity can still require extra protective layers. A board documented for roof use also needs to be approved for the particular external wall insulation system if it is to be used on a façade.

A uniform layer’s thermal resistance depends on its thickness and thermal conductivity. Some PIR boards have lower declared conductivity than typical EPS boards and can provide the required resistance in less space. Use the data for the particular product, facing and thickness range. A single conductivity value cannot describe an entire material family.

White and graphite EPS boards are available with different declared properties. If a thinner board is proposed, check the U-value of the complete element and the surrounding junctions as well as its other properties. A substantial thermal bridge at a parapet can offset part of the benefit gained in the roof field.

Mineral wool products include boards classified as non-combustible. EPS is combustible, and many construction grades declare reaction-to-fire class E. For PIR, check the specific board and the evidence for the proposed construction. The type of foam alone does not establish non-combustibility.

For a completed roof or wall, read the classification alongside the design. Check the layer sequence, fixings, connections and field of application. EPS may suit one part of the building while a different build-up is needed elsewhere. The documented arrangement must also be the one installed.

Fibrous mineral wool can play a role in noise control. The acoustic performance also depends on the assembly’s mass, airtightness and connections. Rigid load-bearing EPS floor boards have a different function from resilient acoustic EPS used to reduce impact sound under a floating screed.

Where premises share a separating floor, examine both the floor construction and flanking sound paths. Low thermal conductivity tells you little about footfall noise. For acoustic EPS, check dynamic stiffness, compressibility, permissible loading and the specified screed construction. Coordinate these choices with the required thermal resistance.

At foundations, check water absorption and the permitted conditions of ground contact. Below floors, assess pressure and long-term deformation. Roofs may also carry maintenance traffic. A material’s CS(10) value describes a compression test and cannot on its own establish the load capacity of the assembly.

Check the membrane, adhesive and separation layers against the board specification. PIR facings can affect vapour diffusion and adhesive choice. Keep substances that attack polystyrene away from EPS. Mineral wool must likewise remain within its documented service conditions. Detail the waterproofing independently of the insulation material.

Add delivery, fixings, protection and junction work to the board price. A thinner refurbishment build-up may avoid alterations to thresholds, although that saving will not always cover the extra material cost. Compare the same area and intended service period using options that meet the same thermal and operational requirements.

EPS manufacturers include Swisspor, Austrotherm, Paneltech and Termo Organika. Use the full product data sheets for comparison. A single project can use different materials in different zones. Wherever they meet, detail how the thermal insulation, waterproofing and fire protection continue across the junction.