| Door | Approx. STC |
|---|---|
| Hollow-core interior door, no seals | 15–20 |
| Solid-core wood door, no seals | 25–28 |
| Solid-core with perimeter seals and door bottom | 30–35 |
| Acoustic door assembly | 40–55 |
A door is usually far weaker than the wall around it. Upgrade the slab to solid core, add adjustable perimeter seals, and fit an automatic drop seal at the bottom. For high-STC rooms, use a factory-tested acoustic door assembly or a sound lock (two doors with a vestibule).