Acoustic Insulation Inspection

Per NBC Section 5.9 and Section 9.11, assemblies separating dwelling units from each other or from common areas must achieve a minimum STC 50 for airborne sound and IIC 50 for impact sound (where applicable). These ratings apply to walls, floors, and ceilings between dwelling units and between dwelling units and service rooms, corridors, or commercial spaces. Assembly designs must be tested per ASTM E90 (airborne) and ASTM E492 (impact) and selected from tested configurations.

1. Verify the specified wall and floor assemblies match tested configurations achieving minimum STC 50 and IIC 50 per NBC

2. Confirm the acoustic consultant's report or design documents identify all demising assemblies requiring sound ratings

3. Check that the specified assemblies account for flanking paths through structural connections, ductwork, and service penetrations

4. Review product data sheets confirming insulation type and thickness match the tested assembly configuration

5. Verify that any upgraded STC or IIC ratings required by provincial building code amendments or project specifications are reflected in the design

- Assemblies specified without reference to tested configurations or laboratory test reports

- Flanking sound transmission paths not addressed in the design

- Provincial amendments requiring higher STC or IIC ratings not incorporated

- Acoustic insulation type or density substituted without confirming equivalent sound performance

Per NBC Section 9.11 and tested assembly specifications, acoustic batt insulation must completely fill the stud cavities of demising walls without compression or gaps. Double-stud or staggered-stud walls must maintain the designed air gap between frames. Resilient channels, where specified, must be installed per the tested configuration. All layers of gypsum board must be installed to the specified thickness and type.

1. Verify acoustic batt insulation fills the full stud cavity height and width with no gaps, voids, or compression

2. Confirm insulation type and density match the tested assembly (e.g., mineral fibre at minimum 2.5 lb/ft3)

3. Check that double-stud or staggered-stud walls maintain the specified air gap with no bridging contact between frames

4. Verify resilient channels are installed at the correct spacing, orientation (flange direction), and fastened only to studs, not through to the opposite frame

5. Confirm gypsum board layers match the tested assembly for type, thickness, and number of layers on each side

- Insulation batts cut short leaving gaps at the top or bottom of the cavity

- Resilient channels short-circuited by screws penetrating through to the stud behind

- Bridging contact between frames in double-stud walls from misaligned blocking or services

- Incorrect insulation density substituted, reducing sound absorption performance

Per NBC Section 9.11, floor-ceiling assemblies between dwelling units must achieve minimum STC 50 (airborne) and IIC 50 (impact). This typically requires a combination of structural isolation, cavity insulation, resilient ceiling suspension, and appropriate floor topping. Concrete floors may require a floating floor or resilient underlay to meet IIC requirements. All components must match the tested assembly configuration.

1. Verify cavity insulation is installed in the full joist or truss depth per the tested assembly specification

2. Confirm resilient ceiling channels or clips are installed at the correct spacing and not short-circuited by fasteners

3. Check that the flooring underlay or floating floor system matches the tested assembly for material type and thickness

4. Verify concrete topping or gypcrete, where specified, achieves the required thickness and is properly isolated from walls with perimeter strips

5. Confirm the ceiling gypsum board type, thickness, and number of layers match the tested assembly

- Resilient ceiling channels short-circuited by drywall screws hitting the joist above

- Floating floor perimeter isolation strips omitted, creating a sound bridge at the walls

- Cavity insulation sagging or displaced, leaving gaps in the assembly

- Concrete topping thickness below specification reducing mass and sound performance

Per NBC Section 9.11 and tested assembly requirements, all penetrations through demising assemblies must be sealed with non-hardening acoustic sealant to maintain the assembly's sound rating. Electrical boxes on opposite sides of a wall must be offset by a minimum of one stud space. Plumbing, mechanical, and electrical penetrations must be sleeved and sealed. Perimeter joints at the intersection of demising walls with floors, ceilings, and exterior walls must be continuously sealed.

1. Verify all perimeter joints of demising walls and floors are continuously sealed with non-hardening acoustic sealant

2. Confirm electrical boxes on opposite sides of demising walls are offset by at least one stud space (400 mm minimum)

3. Check that plumbing and mechanical penetrations are sleeved with resilient material and sealed with acoustic sealant

4. Verify that ductwork penetrating demising assemblies includes in-line silencers or acoustically lined duct sections

5. Confirm no unsealed gaps exist at the top plate, bottom plate, or any service penetration through demising assemblies

- Acoustic sealant omitted at the perimeter of demising walls allowing sound flanking

- Back-to-back electrical boxes creating a direct sound path through the wall

- Pipe penetrations not sleeved or sealed, transmitting both airborne and structure-borne sound

- Ductwork providing a flanking path between dwelling units without acoustic treatment

Per NBC Section 9.11, doors and windows within or adjacent to demising assemblies must not compromise the overall sound rating. Corridor doors to dwelling units typically require a minimum STC 30 rating. Doors in rated assemblies must include acoustic seals, drop seals (automatic door bottoms), and solid-core construction. Windows in exterior walls near noise sources may require enhanced STC ratings per the project acoustic report.

1. Verify corridor entry doors to dwelling units are solid-core and rated to the specified STC (minimum STC 30 per NBC)

2. Confirm acoustic perimeter seals and compression gaskets are installed on all four sides of rated doors

3. Check that automatic drop seals (door bottoms) are functional and make full contact with the threshold

4. Verify windows in exterior walls meet the STC rating specified in the acoustic consultant's report where applicable

5. Confirm door undercuts do not exceed the maximum permitted by the door assembly test report (typically 10 mm maximum)

- Hollow-core doors installed where solid-core rated doors are specified

- Door seals or gaskets missing, damaged, or not making continuous contact

- Automatic drop seals not adjusted properly leaving a gap at the threshold

- Excessive door undercut negating the door assembly's rated STC

Per ASTM E336 (airborne) and ASTM E1007 (impact), field testing of completed assemblies verifies that the installed construction achieves the required apparent sound transmission class (ASTC) and apparent impact insulation class (AIIC). Field results are typically 5 points lower than laboratory ratings due to flanking paths. NBC requires STC 50 laboratory rating; the corresponding field target is typically ASTC 45 or as specified by the project acoustic consultant.

1. Verify field sound testing is performed by a qualified acoustical consultant using calibrated equipment per ASTM E336 and E1007

2. Confirm test locations are representative of typical assemblies and include any locations identified as high risk for flanking

3. Review test results to confirm ASTC and AIIC values meet the project specification or NBC minimum requirements

4. Check that any assemblies failing field testing have been investigated for flanking paths and remediated

5. Verify the final acoustic testing report is submitted to the authority having jurisdiction and the building owner

- Field testing not performed or limited to unrepresentative locations

- Assemblies failing field tests due to unforeseen flanking through mechanical services

- Remedial work not verified with retesting after corrections are made

- Testing performed before all trades have completed work, giving inaccurate results