# Metal mesh and expanded-metal screen

> Woven or expanded metal used in wall build-ups, vents and window screens; attenuation depends on aperture size relative to wavelength, so a mesh that works at 900 MHz can leak badly at 5 GHz.

- Canonical URL: https://emfbase.com/shielding/mesh
- Collection: Shielding & remediation
- Record id: `shielding:shielding-mesh`
- Status: verified
- Last verified: 2026-08-12
- JSON: https://emfbase.com/api/shielding/mesh
- Also known as: faraday mesh, shielding screen, wire mesh

## Key values

- **Form:** mesh
- **Targets:** radiofrequency
- **Grounding required:** Yes — ungrounded installation can make things worse
- **Datasheet attenuation:** 20–40 dB — aperture dependent; performance degrades as wavelength approaches aperture size [sbm-2024]

## Failure modes

- Aperture too large for the frequency of interest: mesh is a low-pass structure
- Panels not bonded to each other, leaving slot antennas at every seam
- Corrosion at fixings destroys electrical continuity over time

## Related records

- [Shielding attenuation](https://emfbase.com/quantities/shielding-attenuation): Decibels of field reduction provided by a material. Every 10 dB is a factor of 10 in power density: 30 dB removes 99.9%, 10 dB removes 90%.

## Sources

- `sbm-2024` Institut für Baubiologie + Nachhaltigkeit (IBN) (2024). *Building Biology Evaluation Guidelines for Sleeping Areas (SBM-2024)*. https://buildingbiology.com/site/downloads/SBM-2024_EVALUATION_GUIDELINES_EN.pdf — ngo, link checked 2026-08-12

Data licence: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Dataset version 2026.08.1. Retrieved from EMFBase, https://emfbase.com.

This record is reference data, not medical or legal advice. Regulatory limits, scientific guidelines and precautionary values are labelled separately and answer different questions.