Sound Isolation Performance Assessment of Traditional and Retrofitted Timber-Framed Dwellings

This study focuses on sound isolation performances of original timber-framed interior wall and floor components in traditional-framed dwellings in Turkey and 19th century mud-brick samples used as infill within the timber frame. The acoustical ramifications of some retrofits proposed in the contexts of minimum intervention and refunctioning the traditional dwellings are assessed in reference to the relevant standards. Field measurements show that sound isolation performances of the original timber-framed wall and floor are ineffective. The results of this study show that acoustical retrofits applied on the original wall keeping its wood lath and mud-brick infill are about 5–7 dB in the weighted sound reduction index (R_W) and are more effective than those applied on the reconstructed wall. Sound transmission loss values of 50- and 100-mm-thick authentic mud samples are 22–38 and 30–43 dB, respectively, between 125 and 4,000 Hz. The sound absorption coefficient at mid frequencies and the noise reduction coefficient of 50-mm-thick mud samples are 0.28 and 0.23, respectively. These results signal the importance of keeping traditional construction techniques of wall and floor during retrofits to improve the sound isolation performance. Adobe mixtures similar to the 19th-century mud-bricks can be of guidance for the production of innovative soundproofing earth-based building materials.

Occupants living in traditional timber-framed houses suffer from noise-related problems even after these dwellings undergo repair works. According to field measurements, traditional timber-framed wall and floor components in these dwellings have inadequate sound isolation properties. On the other hand, studies show that mud-brick used as infill within the timber walls and floors, as well as mud plaster covering the wood lath, are important layers and help reduce noise transmission between the rooms in the dwellings. This means that traditional mud-based materials should be kept during retrofit works. Laying carpets or filling the voids at door edges and timber floor surfaces are minimum interventions but not enough to eliminate the noise passage. If one side of the timber-framed wall is covered with thin and insulated drywall, it provides sufficient sound insulation between the rooms. When enhanced sound isolation is needed, for instance, when a room is refunctioned as a meeting room during renovations, a separate mounting of drywall and separate mounting of timber ceiling are required to be done. This means that drywall or timber ceiling is attached in a way that does not touch the existing sublayer.