Acoustics

How do I keep outdoor noise out?

Short answer

The façade matters most. The Belgian comfort standard asks for at least 26 dB façade insulation in habitable rooms, and more where it is louder outside.

Explanation

According to NBN S 01-400-1 the façade insulation (DAtr) must be greater as outdoor noise increases. Windows, roller-shutter boxes and ventilation grilles are usually the weak spots. Outside, the WHO advisory value for road traffic remains 53 dB Lden.

Rules of thumb

• Minimum façade insulation in habitable rooms: DAtr ≥ 26 dB. [SW-S12]
• The requirement rises with the outdoor noise level (formula in the standard). [SW-S12]
• On busy streets choose acoustic ventilation grilles; ordinary grilles let a lot of noise through. (practical tip, not a source value)

Pitfalls

• Closing grilles against noise makes the air worse; choose acoustic grilles instead of less ventilation. [SW-S30]

Search terms

These search terms are in Dutch; only terms that also find a topic in English are links.

gevelisolatie ramen verkeerslawaai ventilatierooster

Read also

• How much traffic noise is still healthy?
• How much ventilation does a room need?

Sources

1. SW-S08 Compendium of WHO and other UN guidance on health and environment — hoofdstuk 11 Environmental noise — WHO (Reference date 2026-09-27)
2. SW-S12 Akoestische normeisen woongebouwen NBN S 01-400-1 (overzicht) — Buildwise (voorheen WTCB) (Reference date 2026-09-27)
3. SW-S30 Tips voor beter en energiezuiniger ventileren — Milieu Centraal (Reference date 2026-09-27)

Reference date: 2026-09-27 · Translated with AI from the Dutch original.