Contribution of Internal Wall Assemblies to Wood-Frame Floor/Ceiling ASTC Performance


  • Simon Edwards HGC Engineering
  • Joonas Niinivaara HGC Engineering
  • Alex Lorimer <p>CAA</p><p>HGC Engineering</p>


In wood-frame buildings, internal walls directly mounted to the joists above (i.e., penetrating any drop ceiling) provide a considerable flanking path for vertical sound transmission, decreasing the field Apparent Sound Transmission Class (ASTC) performance of the overall as-built assembly. With the National Building Code transition to regulating field ASTC performance from design partition STC performance, flanking paths such as these have the potential to change the acoustical performance of an otherwise well-built floor/ceiling assembly even with reasonable perimeter flanking controls at demising walls. This article presents a comparison of field measurements demonstrating the acoustical effects of flanking through internal walls mounted directly to the joists of the wood-frame floor/ceiling assembly above.

Author Biographies

Simon Edwards, HGC Engineering

Project Consultant

Joonas Niinivaara, HGC Engineering

Project Consultant

Alex Lorimer, <p>CAA</p><p>HGC Engineering</p>

Acoustic ConsultantSenior Associate



How to Cite

Edwards S, Niinivaara J, Lorimer A. Contribution of Internal Wall Assemblies to Wood-Frame Floor/Ceiling ASTC Performance. Canadian Acoustics [Internet]. 2017Aug.19 [cited 2021Jun.17];45(3):62-3. Available from:



Proceedings of the Acoustics Week in Canada