Complete construction reference for duct penetrations, silencer installation, flex connections, and acoustic sealing across all four served rooms in the .
CUSTOMIZABLE -- Duct hanger and support bracket brand, vibration isolator bracket manufacturer (if matching deflection spec), duct tape and mastic brand, access panel frame finish, insulation jacket colour on exposed runs.
DO NOT ALTER -- Duct dimensions and routing paths, flexible connector length and type at wall penetrations, sleeve oversizing dimensions, silencer attenuation ratings and positions, terminal velocity limits per grille, duct liner type and thickness, number of bends before and after silencers, acoustic lagging specifications on exposed ductwork. HVAC penetrations are the most common source of acoustic flanking -- follow details exactly.
Supply and return runs branch from the buffer spine partition. Each penetration uses oversized sleeves and flex connectors to maintain acoustic isolation.
Every duct penetration through the buffer spine wall requires an oversized sleeve, neoprene isolation gasket, acoustic putty, flexible duct connector, and fire damper. Select a run to view its specific cross-section.
All silencers are installed in the buffer zone, immediately before the wall penetration. Flanged connections ensure airtight sealing. Lined silencers use mineral wool acoustic lining with a perforated metal facing.
The flexible duct connector is the critical acoustic break at every wall penetration. It prevents rigid-path sound transmission from the duct system into the room walls. Minimum 300mm length is required for effective vibration isolation.
Neoprene-coated fiberglass fabric, minimum 2-ply construction. Must be rated for HVAC use and fire-resistant (Class 1 or 0 fire rating). Inner surface smooth to minimize turbulence and noise regeneration.
Secure with stainless steel band clamps at each end. Do not stretch taut — allow slight sag for vibration absorption. Seal clamp joints with mastic sealant. Never exceed 300mm unsupported span.
Both indoor units (IDU-03 and IDU-04) are ceiling-cassette mounted within the buffer zone duct band. All connections must be vibration-isolated to prevent structure-borne noise transmission into the acoustically treated rooms.
Ceiling cassette units mounted on spring-loaded vibration isolators (minimum 95% isolation efficiency at operating speed). Neoprene pads between mounting brackets and ceiling structure. All-thread rods with rubber grommets for ceiling suspension.
Condensate drain lines must use flexible PVC connectors at the unit connection point. Rigid drain pipe must not contact the IDU directly. Use a minimum 150mm flexible section with neoprene-lined pipe clips where supported from structure. Drain traps must maintain water seal at all times.
Liquid and gas lines from the outdoor unit pass through the building envelope. Each penetration requires a neoprene-lined sleeve with fire-stop sealant at both faces. Lines must be isolated from the sleeve with rubber grommets — copper must not contact masonry or steel structure.
All duct runs within the buffer zone and room plenums must use neoprene-isolated clevis hangers or spring isolators. Pad material: neoprene, 25mm minimum thickness, 40-shore durometer. Load rating: sized for 3× actual duct weight to prevent bottoming-out. Maximum hanger spacing: 1200mm for rectangular duct. Trapeze hangers with rubber channel liners preferred over single-rod hangers for runs over 3m.
Each room's NC target is the SSOT value from ACOUSTIC-CONSTANTS.js. Silencer sizing must achieve the HVAC noise budget allocation for each room.
| Room | NC Target | HVAC Budget (dB) | Silencer Run | Silencer Attenuation (dB) | Terminal Velocity (m/s) | NC at Diffuser (max) | Margin | Status |
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NC targets are locked values from the acoustic design specification. Silencer dimensions and attenuation values were engineered specifically to meet these targets. Any change to duct sizing or silencer specification requires full NC budget recalculation.
Follow this exact sequence for each of the four duct penetration runs. Steps are ordered to prevent rework and ensure acoustic integrity.
Never use rigid connections through walls. Every duct penetration through an acoustically rated wall must include a flexible duct connector (minimum 300mm length). Rigid-to-rigid connections create an acoustic bridge that completely bypasses the wall's STC rating. This is the single most common cause of HVAC-related noise failure in studio construction.
Oversized sleeve is mandatory. The duct must NOT touch the wall structure at any point. The sleeve must be 50mm larger than the duct on all sides, creating a continuous air gap that is packed with mineral wool and sealed with acoustic putty. Any metal-to-structure contact creates a flanking path.
Fire dampers required at all fire-rated wall penetrations. Intumescent fire dampers must be installed per local fire code at every point where ductwork penetrates a fire-rated wall or ceiling assembly. Dampers must be accessible for periodic inspection and maintenance. Document all damper locations on the as-built drawings.
NC targets are the Single Source of Truth values. Silencer sizing, duct velocity, and diffuser selection have all been engineered to achieve the locked NC targets: VO Live NC-20, Control NC-25, Studio NC-25, Editing NC-35. Any field modification to silencer length, duct size, or diffuser type must be re-verified against these targets before installation.