Check that each floor and wall assembly on the architectural drawings matches a tested or designed assembly, including topping, acoustic mat, and any ceiling, and that structural, MEP, and finish drawings do not change it. Then check the places where sound bypasses the assembly: wall-to-floor junctions, beam and column connections, and MEP penetrations.
Why mass timber assemblies are different
WoodWorks’ paper Acoustics and Mass Timber: Room-to-Room Noise Control (Richard McLain) explains that bare mass timber floor and wall assemblies are seldom adequate for noise control. Owners often want the underside of the panels exposed, so acoustic layers go on top. That makes mass timber floors asymmetric, unlike light-frame floors, which usually add treatments above, within, and below the framing.
The WoodWorks summary describes the common additions: a poured concrete or gypsum-based topping, usually 1 to 3 inches thick, or a dry-laid floor system, plus decouplers such as roll-out isolation mats or discrete isolators between the panel and the topping. The paper notes that IBC sound requirements apply to dwelling unit separations in multifamily buildings, with lower ratings allowed when field tested; check the ratings in your adopted edition. Sources verified October 22, 2026. The topping itself is coordinated in concrete toppings on mass timber floors.
Flanking: where sound goes around the assembly
The paper says that even well-designed assemblies need attention to flanking paths at assembly intersections, beam-to-column and wall connections, and MEP penetrations. It describes resilient connection isolation and sealant strips that carry load while breaking hard, direct contact between members.
For multifamily buildings, it describes breaking the topping at unit separation walls, and in some cases breaking the floor panels at each unit wall. It notes that breaking panels can make manufacturing and erection less efficient, so the choice should be discussed with the manufacturer and installer.
Ten acoustic coordination checks
- Assembly basis. Each floor and wall type names the tested or designed assembly it relies on, and the acoustic consultant’s report, if any, is referenced.
- Layer match. The topping, mat, and finish floor on the floor type match the sections, structural notes, and specifications.
- Topping thickness and weight. The structural drawings carry the same topping thickness and material as the architectural floor type, so the added load is accounted for.
- Exposed ceilings. Where the reflected ceiling plan shows exposed timber, the floor above still has its full acoustic build-up.
- Applied ceilings. Where ceilings are added below, the ceiling type and any resilient channels or clips match the assembly the design relies on.
- Topping breaks. If the design breaks the topping at unit walls, the break is shown on plans and details and aligns with the partition.
- Wall-to-floor junctions. Junction details show any isolation strips or other flanking control the acoustic design calls for.
- Connections. Beam, column, and wall connection details show the isolation the design requires, and the structural details do not omit it.
- Penetrations. MEP penetrations through acoustic floors and walls have a sealing detail, so they do not become flanking paths.
- Moisture timing. The schedule does not install mats or toppings over wet timber. WoodWorks’ moisture guidance suggests a limit such as 16% before an acoustic mat or topping.
Record each question so it can be closed
For each issue, record the assembly type, the sheets and specification sections involved, what disagrees, and who must decide, usually the architect with the acoustic consultant. When a topping, mat, or ceiling changes, check the structural load notes, sections, and finish schedules together. See WoodWorks’ moisture management guidance and the mass timber drawing coordination checklist for the related checks.
Where Groundbook fits
Upload the architectural, structural, and MEP drawings with the relevant specification sections, and run a cross-discipline review. Groundbook flags potential disagreements, such as an opening shown on an MEP plan but missing from the structural panel layout, with links to each source sheet. Your team decides what each finding means for the fabrication package. Groundbook does not check structural capacity, fire ratings, or the fabricator’s model.