Why do you always hear footsteps upstairs? Analyzing noise propagation and solutions from the perspective of building science

1. Troubling phenomenon: Why is residential noise so loud that it is heard everywhere?

Many residents report being frequently disturbed by footsteps from above, pets running around, objects falling, and even furniture being pushed and pulled. These noises not only impact their quality of life but can also cause conflicts with neighbors. The root cause lies in the inadequate insulation of building materials and structures against impact noise . This article examines the principles of noise propagation from a scientific perspective and offers authoritative solutions.

2. Noise Types and Transmission Paths

Noise in a residence can be divided into two main categories:

1. Airborne sound (such as talking and television sound): It is transmitted through air vibration and can be blocked by walls, doors and windows.
2. Impact sound (such as footsteps, objects falling): Vibrations generated by objects hitting the floor or wall are transmitted through the building structure and are currently a difficult point in residential sound insulation.

Impact sound propagation path :

• Direct transmission : Vibration passes through the floor → wall → ceiling → indoor air, forming audible noise.
• Lateral transmission : Vibration spreads to adjacent rooms along lateral structures such as walls and pipes.

3. Building materials and structural defects: Where are the noise “loopholes”?

1. Inadequate traditional floor design

• Insufficient thickness : In the past, residential floors generally used 100-120mm thick reinforced concrete, but no sound insulation layer was set, and the impact sound insulation performance was poor.
• Rigid connection : The floor slab is directly and rigidly connected to the wall, which improves the vibration transmission efficiency. Experiments show that the sound insulation of ordinary floor slabs to footsteps is only about 50 decibels (normal conversation is 60 decibels).

2. Lack of sound insulation

• Traditional technology : Floor slabs are mostly cast in concrete and lack elastic sound insulation pads;
• Wall hollowing : The hollow structure inside some lightweight partition walls exacerbates vibration transmission.

3. Doors, Windows and Pipes "Sound Bridge"

• Gaps in doors and windows : Sliding windows and door frames are not tightly sealed, forming airborne sound transmission channels;
• Pipes passing through walls : Water and electricity pipelines are not soundproofed when passing through floor slabs, and vibrations are transmitted along the pipes.

4. Scientific solution: comprehensive upgrade from materials to structure

1. Floor sound insulation renovation (government recommended technology)

• Sound insulation pad : Laying 5-10mm elastic material (such as rubber sound insulation pad, floating floor) on the floor can reduce the impact sound by 15-20 decibels;
• Ceiling vibration reduction : Install an elastic sound-insulating ceiling (filled with sound-absorbing cotton) to prevent vibration from being transmitted to the indoor air.

2. Wall, door and window optimization

• Wall soft covering : Use wooden sound-absorbing panels or sound insulation felt to cover the wall to reduce lateral sound transmission;
• Seal doors and windows : Replace double-glazed windows and install sound insulation strips at the bottom of the doors to block airborne sound.

3. Government-mandated standard upgrades

According to the "Residential Project Specifications" and "Civil Building Sound Insulation Design Specifications" implemented in 2025:

• Floor impact sound limit : required to be no more than 65 decibels (original standard 75 decibels), close to the level of developed countries;
• Mandatory sound insulation measures : New residential buildings must adopt sound insulation designs such as floating floors and elastic ceilings.

5. Data comparison: Differences in sound insulation between new and old buildings

Noise type Traditional residential sound insulation (dB) New standard residential sound insulation (dB) Footsteps 50-55 65-70 (reduced by 10-15 dB) Objects falling 45-50 60-65 (reduced by 15 dB) Sliding and pulling furniture 40-45 55-60 (reduced by 15 dB)

(Note: A 10-dB decrease in the decibel level reduces the perceived noise loudness by approximately 50%)

6. Government Action: Promoting the Construction of “Quiet Homes” by All

1. Strict supervision of new projects

• Starting from 2025, a new "sound insulation performance test" will be added to residential acceptance, and projects that fail to meet the standards will not be completed and filed;
• Promote the "Residential Sound Insulation Structure Atlas" and provide standardized construction plans.

1. Support for the renovation of old residential areas

• Included in the urban renewal plan, 30%-50% financial subsidies are provided for floor sound insulation and door and window sealing renovations;
• Pilot "Community Noise Detection Service Station" to provide free technical consultation.

1. Public Science Popularization and Rights Protection Guidelines

• Released the "Residential Sound Insulation Self-Inspection Guide," allowing residents to conduct preliminary indoor noise testing using a mobile app;
• Clarify the path to rights protection: negotiation → property mediation → 12345 complaint → judicial prosecution.

Conclusion: Let "quiet" become the standard of residence

The issue of residential noise is essentially a struggle between architectural science and quality of life. By upgrading materials, optimizing structures, and strengthening standards, the government is working tirelessly to transform the ideal of "quiet homes" into reality. We also urge the public to proactively employ soundproofing during renovations and reduce vibration in their daily lives, so that we can all work together to create harmonious and livable homes.