When to use this system
An intermediate floor with termPIR® insulation is used when two storeys have different temperatures:
- Apartment above garage — required U ≤ 0.25 W/m²·K (WT 2021 for floor above unheated space). Met with 90 mm termPIR® AL.
- Apartment above gateway passage — direct contact with outdoor air, required U ≤ 0.25.
- Unit above underground car park — temperature in car park often 5–10°C in winter.
- Top-storey floor below non-heated attic — required U ≤ 0.25 W/m²·K.
Why PIR instead of mineral wool in the floor
| Aspect | termPIR® AL | Mineral wool (rigid board) |
|---|---|---|
| Thickness for U ≤ 0.25 | 90 mm | ~160 mm |
| Loss of usable space | minimal | significant (room height) |
| Compressive strength | ≥120 kPa, rigid | lower, deflects under screed |
| Water resistance | water absorption < 2% | high (capillary), mould risk |
| Weight | ~3 kg/m² (100 mm) | ~12 kg/m² (100 mm) |
| Underfloor heating | aluminium reflects heat | no thermal benefit |
Installation requirements
- Waterproofing from the side of the colder room (e.g. garage) — bitumen felt or waterproofing membrane.
- Separating film between termPIR® and the screed — prevents water from the concrete mix being drawn into the insulation.
- Concrete screed min. 8 cm for traffic areas; 6.5 cm for anhydrite screed with underfloor heating.
- Edge expansion tape at walls.
Technical documentation
termPIR® 2025 brochure (Gór-Stal, 2025-04-23, pp. 14–15). Holds CE marking (EN 13165), AT-15-7148, PZH hygiene certificate approving direct contact with food (critical for floors in food-industry facilities).
Layer composition
| # | Layer | Thickness | λ | Role |
|---|---|---|---|---|
| 1 | Concrete screed | — | — | top layer / floor finish |
| 2 | Separating / construction film | — | — | separating slip layer |
| 3 | termPIR® AL | 80–250 mm | 0,022 W/(m·K) | thermal insulation |
| 4 | Bitumen felt / waterproofing membrane | — | — | damp-proof layer |
| 5 | Concrete slab | — | — | load-bearing structure |
U-value by insulation thickness
| termPIR® thickness | U [W/m²·K] | Meets WT 2021 (roof U ≤ 0.15) |
|---|---|---|
| 80 mm | 0,26 | — no |
| 100 mm | 0,21 | — no |
| 120 mm | 0,18 | — no |
| 150 mm | 0,14 | ✓ yes |
| 160 mm | 0,13 | ✓ yes |
| 180 mm | 0,12 | ✓ yes |
| 200 mm | 0,11 | ✓ yes |
| 220 mm | 0,10 | ✓ yes |
| 250 mm | 0,08 | ✓ yes |
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