Sound Transmission Class: window
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 | OITC rating (dimensionless) | STC rating (dimensionless) | assembly description | construction detail | fire rating hr (hr) | frequency weaknesses | thickness in (in) | weight psf (lb/ft2) |
|---|---|---|---|---|---|---|---|---|---|
| window | window_double_pane_6mm_12mm | 26 | 32 | Double pane IGU asymmetric with larger air gap | 6mm/12mm air gap/6mm asymmetric IGU; thermally broken aluminum frame; some STC benefit from asymmetry | 0 | Asymmetric glass masses (unequal thickness) stagger coincidence dips; 12mm gap adds; traffic noise audible | 1.5 | 7.5 |
| window | window_double_pane_std | 22 | 28 | Double pane insulating glass standard | 1 in IGU: two 3mm panes; 1/2 in air gap; aluminum frame; no acoustic interlayer | 0 | Mass-air-mass resonance dip ~100-200 Hz; coincidence both panes; standard IGU poor for sound | 1 | 3.2 |
| window | window_double_pane_wide_gap | 31 | 38 | Double pane wide air gap | 6mm / 4 in air space / 6mm; aluminum frame; wide gap for acoustic benefit | 0 | Wide gap improves low-mid freq; mass-air-mass resonance shifted lower; excellent vs standard IGU | 5 | 7.5 |
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