Sound Transmission Class: floor_ceiling
Sound Transmission Class (STC), Impact Insulation Class (IIC), and Outdoor-Indoor Transmission Class (OITC) ratings for building assemblies — walls, floor-ceilings, doors, windows, partitions — per ASTM E90/E413/E492/E1425
| assembly type | assembly id | IIC rating (dimensionless) | STC rating (dimensionless) | assembly description | construction detail | fire rating hr (hr) | frequency weaknesses | thickness in (in) | weight psf (lb/ft2) |
|---|---|---|---|---|---|---|---|---|---|
| floor_ceiling | floor_concrete_4in | 28 | 44 | 4 in concrete slab bare | 4 in NWC slab; no topping; no ceiling | 1 | Bare slab IIC poor; coincidence dip ~125 Hz; add floating floor or carpet for IIC | 4 | 50 |
| floor_ceiling | floor_concrete_6in | 30 | 51 | 6 in concrete slab bare | 6 in NWC slab; no topping; no ceiling | 1.5 | STC improves with mass; IIC still poor without carpet/floating floor | 6 | 75 |
| floor_ceiling | floor_concrete_6in_carpet | 60 | 51 | 6 in concrete slab with carpet and pad | 6 in NWC slab; carpet and foam pad on top; no suspended ceiling | 1.5 | Carpet adds ~30 IIC points; STC unchanged (carpet doesn't block airborne much) | 6.5 | 77 |
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