Mullion to Internal Partition Closures
The condition of an internal partition meeting a glazed region of the curtain wall commonly gives rise to acoustic problems. In particular, this is the case if the internal partition provides a high sound reduction performance and the abutment occurs at the line of a narrow width mullion.
The depth of a partition with a high sound reduction index (SRI) is frequently substantially greater than that of the mullion width. Traditionally, this mismatch in dimensions is visually and practically accommodated by the introduction of a short section of partition having a stepped-down thickness (normally reduced to the mullion width).
Whilst comparatively small when compared to the overall partition area, this section is still capable of substantially reducing the overall sound reduction performance. The following example demonstrates this effect:
Element | Length | Rw |
Main Partition | 3.7m | 53dB |
Infill Section | 0.3m | 32dB |
OVERALL | 43dB |
In this example the small section of reduced thickness partition has decreased the overall performance by 10dB (subjectively a doubling in perceived loudness). The lower SRI value of the thin partition section arises primarily as a result of the dramatically reduced depth of the internal void. Indeed for some constructions a void may be completely absent.
Siderise can advise on special constructions for this condition that can maximise the achievable SRI. These may be built-up arrangements or occasionally composite panels. Both generally would incorporate high mass boards and limp membrane combinations.
Due to the wide variation in possible requirements, we recommend that the specific condition is discussed with our technical department.
