Design with B&C acoustic flooring

B&C (Batten & Cradle Acoustic Flooring, New Zealand) supplies a resilient raised-floor acoustic system for airborne and impact sound insulation of timber floors. The system is tested over CLT to ISO 140 and ISO 140-8 and rated to ISO 717, and SPEC Toolbox carries the tested build-ups for acoustic floor design to the NCC and NZ Building Code.

The integration covers the B&C Batten & Cradle acoustic floor build-up, assembled over a CLT floor from the following components.

• B&C Acoustic Cradle: a resilient cradle seated on the CLT floor, at 450 mm centres, that isolates the floor from the structure.
• B&C Structural Batten: a 42 mm LVL batten seated in the cradles at 400 mm centres, carrying the floor finish.
• Floor finish screwed to the battens: 20 mm Laminex Strandfloor tongue-and-groove, Superpine particle board, or James Hardie Secura flooring.
• Acoustic insulation in the batten cavity (R1.2 Pink Batts) and, with a ceiling, in the ceiling cavity (R2.2 Pink Batts), below a resiliently mounted GIB Fyreline plasterboard ceiling.

At a glance, the B&C acoustic flooring supports:

• Airborne and impact sound insulation of CLT floor/ceiling assemblies.
• Installation over CLT floors (tested over Red Stag CLT), with a range of floor finishes and ceiling build-ups.
• Residential and multi-unit floors where an airborne and impact rating is required.

• A resilient batten-and-cradle system. The LVL structural batten is seated in the B&C acoustic cradle rather than fixed to the structure, isolating footfall and impact so that less structure-borne noise reaches the room below.
• Tested complete build-ups over CLT. The integration carries laboratory-measured airborne and impact ratings for the whole floor/ceiling assembly, not just the isolation layer, with tested airborne ratings (Rw) to 69 and impact ratings (IIC) to 60.
• Tunable to the target. The floor finish, the cavity insulation, the CLT thickness and the ceiling (plasterboard layers, cavity, resilient mounts) are varied to reach the required airborne (Rw, STC) and impact (Ln,w, IIC) rating.
• A serviceable raised floor. The batten-and-cradle cavity provides a levelling zone and space for services above the CLT floor.

The B&C acoustic flooring is available in the SPEC Toolbox acoustic floor design:

• assemble a B&C batten-and-cradle build-up over a CLT floor, with cavity insulation and a ceiling, to meet the airborne target (Rw, Rw+Ctr, STC) and the impact target (Ln,w, L’nT,w, IIC).

Panel behaviour is taken from the integrated database of tested build-ups (University of Auckland Acoustics Testing Service, series T2210); field performance depends on installation and flanking, which the acoustic consultant verifies.

Performance is established by laboratory test, not by structural calculation. The B&C build-ups over CLT were tested at the University of Auckland Acoustics Testing Service for airborne (ISO 140) and impact (ISO 140-8) sound insulation, rated to ISO 717, and reported with the weighted airborne sound reduction (Rw, with the C and Ctr spectrum adaptation terms and STC), the weighted normalised impact sound pressure level (Ln,w with CI) and the impact insulation class (IIC). Across the tested build-ups the airborne rating (Rw) ranges from about 50 to 69 and the impact rating from about IIC 41 to 60 (Ln,w about 69 down to 46), depending on the floor finish, cavity insulation, CLT thickness and ceiling. The ratings support NCC (Australia) and NZ Building Code compliance; field performance depends on the installed construction, perimeter isolation and flanking transmission, and trial on-site testing is recommended before full installation.