In a recent Christchurch multi dwelling project, Earthwool Glasswool R2.2 Acoustic Wall Insulation was accepted as a substitute for 11kg acoustic insulation infill within the GIB Barrier System to achieve New Zealand Building Code intertenancy requirements (target STC ≥55).

What was the challenge?

Under the New Zealand Building Code, a Sound Transmission Class (STC) for walls, floors and ceilings of no less than 55 is required for building elements between occupancies in household units.

To meet these requirements, project managers, DC Living, have specified the GIB Barrier system for the internal walls of the multi-unit townhouse project. Featuring double stud framing, 13mm plasterboard on each side, and 11kg/m³ density acoustic insulation, the system achieves a 56-68 STC.

Seeking to maximise the overall comfort and indoor health of the building, in addition to meeting thermal and acoustic requirements, the project manager has requested a substitution for the specified R2.2 wall insulation infill.

What was the solution?

Knauf Insulation proposed that the Earthwool Glasswool R2.2 Wall insulation be substituted into the wall system. This product substitution is supported by a statement of equivalence from Marshall Day Acoustics, confirming that an insulation infill material of the same density and thickness may be used in the system without affecting acoustic performance.

Further technical support from Winstone Wallboards — the manufacturer of the GIB system — confirmed that the GIB system's warranty and fire performance would not be impacted by the substitution.

At 90mm thickness, the R2.2 Wall insulation is designed to fit snuggly between the studs and dwangs, offering a smooth friction fit installation and delivering exceptional acoustic performance.

Marshall Day's statement of equivalence paves the way for the Earthwool Glasswool R2.2 11kg/m³ Wall insulation to be an accepted solution for GIB inter-tenancy wall system. This will afford specifiers, installers, and homeowners the opportunity to take advantage of Earthwool Glasswool's unique benefits without compromising on performance.

What was the result?

Substituting the Earthwool Glasswool wall product allowed the inter-tenancy wall system to achieve the required acoustic and thermal performance without impacting the integrity of the system. It also allowed the project manager to take advantage of Earthwool Glasswool’s range of unique benefits that will deliver positive outcomes for occupants throughout the life of the building.