Why is the noise always coming from upstairs? An industry insider reveals the truth!

Why is the noise always coming from upstairs? Let industry insiders explain the reasons:

Case Study:

Ms. Chen bought her house in 2007 at an average price of 12,000 yuan per square meter, which has now risen to 30,000 yuan per square meter. She was initially happy to move from her old house to her new one, but to her surprise, the sound insulation of the house doesn't match the high price. Besides the noise from the air conditioner and downstairs neighbors, there's also the sound of the toilet drainpipes. At night, these noises make it impossible for her to sleep.

Zhang Sanming , a leading authority on building sound insulation in China and from the Institute of Architectural Technology at Zhejiang University, said :

"This is a common problem among most homebuyers; nine out of ten buyers overlook the sound insulation of buildings. As early as 1988, my country promulgated the 'Code for Sound Insulation Design of Civil Buildings,' which stipulates the permissible noise levels in bedrooms and living rooms, as well as the sound insulation levels that partition walls and floors should achieve. In recent years, residential design has made great progress, paying more and more attention to the functional layout of rooms, greening, and building appearance, but the issue of building sound insulation is still rarely considered."

Our country's sound insulation standards are relatively lenient. However, in reality, many buildings still fail to meet these standards, and this situation is similar across the country. The most prominent issue is the sound of impacts on the floor. For example, the sound insulation is acceptable for conversations between upstairs and downstairs neighbors, but the sound of someone dragging a chair upstairs can be very loud downstairs.

Although there are national sound insulation standards, they are not included in the acceptance criteria for completed residential buildings, nor are they listed on the building certificate of conformity. Many developers only use sound insulation standards when applying for green building or healthy building certifications. This explains why many prohibitively expensive properties have unsatisfactory sound insulation.

In theory, sound insulation should be addressed by the developer, not the homeowner. This is because most residential buildings use concrete, and concrete floor slabs are poor at isolating footsteps, running, jumping, and the impact of moving furniture. Furthermore, larger room sizes make the floor more prone to vibration. Additionally, the floor slab may contain numerous embedded electrical conduits, network cables, heating pipes, and other wiring. Increased voids and reduced mass make sound insulation a significant problem. Techniques such as floating floors, wooden flooring, or damping panels are needed to improve sound insulation performance and meet the national standard: a floor impact sound insulation value of ≤75 decibels.

Back in the 1980s, Zhang Sanming was commissioned by the then Ministry of Construction to conduct a nationwide survey on residential sound insulation. The poor sound insulation of the floors at that time left a deep impression on him. However, more than 20 years later, the situation has not improved much. "It's not a technical problem, it's not that it can't be done well, but that (developers) don't do it. In fact, sound insulation treatment is not expensive, the material cost per square meter only increases by about 30 or 40 yuan. If this step is done, at least there will be no problem with the sound insulation between floors."

Industry experts recommend that floor soundproofing should ideally be completed during construction.

The problem of sound insulation in a house is something that 28-year-old architectural engineer Xiao Qian just happened to encounter:

"My wife also suffered from neurasthenia due to the noise from the floorboards upstairs and downstairs. We tried many measures, but there was nothing we could do about the old house, so we had no choice but to sell it."

The best and most economical way to soundproof floors, stairs, and corridors is during the construction phase, and the cost is not high. However, developers generally either don't do it at all, or only do it in show flats, although some brand-name developers do a decent job in this area. Floor slabs are generally similar; their thickness is not for sound insulation but only for load-bearing capacity. The key is to lay flexible soundproofing materials; if everything is rigid, vibrations will easily transmit sound. What's more troublesome is that, from what I understand, once you've bought a house with soundproofing problems, it's very difficult to improve it later. Airborne sound is relatively easier to deal with, such as air conditioner noise; good double-glazed windows can effectively block it. But for vibrations transmitted through the floor slab, while a suspended ceiling might improve it to some extent, the effect is minimal.

The above information is sourced from: Hangzhou Housing Network and Tsinghua University's "Architectural Acoustics Network".

The lack of sound insulation from impacts with the floor is a current reality. The only solution is to take proactive measures to soundproof and dampen the floor, thus avoiding troublesome neighborhood disputes.

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