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Noise between rooms is a top complaint in apartments and hotels. The interior door is often the weakest link. This guide covers what actually blocks sound and the standards to specify.
The STC Rating
Sound Transmission Class (STC) measures how much sound a door blocks. Typical hollow-core doors score STC 20–25 (voices audible). Solid-core and acoustic doors reach STC 30–35 (speech muffled).
What Drives Performance
- Core – Solid timber, mineral, or acoustic foam cores outperform hollow cores.
- Mass – Heavier leaves transmit less sound.
- Perimeter seals – Drop seals and jamb gaskets close the gap where sound leaks.
- Frame & install – Gaps around the frame ruin a good door; acoustically caulk and fit tight.
Specifying for Projects
For wooden interior door elegance with quiet, choose a solid-core leaf (STC 30+) plus perimeter seals. Hotels and clinics may need STC 35 acoustic rated soundproof door assemblies with certified frames.
Common Mistakes
| Mistake | Fix |
|---|---|
| Hollow core in bedrooms | Use solid core |
| No bottom seal | Add automatic drop seal |
| Gaps at frame | Acoustic caulk + shims |
FAQ
Do seals hurt accessibility?
Automatic drop seals retract when the door opens, so they stay ADA-friendly.
Get Quiet Doors
Contact KENT for STC-rated interior and soundproof door options.
