Noise issue in high-rise apartment, Rahmen structure is alternative
Noise issue between intermediate floors of high-rise apartment houses has caused serious disputes among residents. To overcome this problem, South Korean government has strengthened the thickness of the intermediate floor and raised the standard for impact noise. Since 2014, the thickness of the concrete slab has been reinforced to 210mm in the bearing wall structure. With the soundproof layer, Ondol floor layer, and the finishing material on the structural floor, the total thickness of the concrete slab can reach a thickness of 330mm. The concrete slab thickness of a Rahmen structure apartment is 150 mm. This reduction represents a significance cost savings.
The residential buildings built since 2014 have been reinforced to meet both the standard floor structure defining slab thickness and the standard for impact sound. It is also important for the intermediate floor noise to convey the vibration as well as the floor thickness or the impact sound. Basically, the sound of the floor occupies a large part of
the intermediate floor noise. In other words, floor vibration is transmitted to another unit on a wall or a pillar. In the bearing wall structure, the floor sound will likely pass through the wall to other units. On the other hand, the wall has an auxiliary role, and the core is the column. Floor impact sound and vibration are dispersed into beams and columns, not walls. It is also the reason why the Rahmen structure is attracting attention in recent years.
According to the results of the survey conducted by the Ministry of Land, Infrastructure and Transport, the Rahmen type structure is 1.2 times higher than the wall type structure in sound proof performance. But still many construction companies are reluctant to build a Rahmen structure. This is because construction costs are getting higher.
“The columns are not integral with the floor, so there is less noise”, explained a senior researcher at the Institute of Construction and Urban Research under the Korea Institute of Construction Technology. “The Rahmen structure is easy to change the floor plan when it is needed. It is flexible and the life cycle of the building is longer”, he also said.
Despite these advantages, 80% of high-rise apartments built in South Korea are the bearing wall structures. In South Korea, as the number of households increases, the size and area of houses are decreasing. The preference both on energy saving type and housing cost saving type is increasing. So, the South Korean government’s policy on long-life housing, which is easy to change the internal wall structure, is getting stronger. According to the needs of the users, the Rahmen structure of high-rise apartments is expected to increase more and more. Wood infill wall system in North America and Europe has attracted attention as a proven system that can efficiently apply non-load bearing wall partitions to Rahmen structures. In Korea, it is not easy to find the wood infill wall cases applied to high-rise apartments. However, it is encouraging that both architects and builders are satisfied with the cases applied to commercial buildings. I look forward to hearing more success stories of commercial buildings spreading into the high-rise housing market soon as well.