BC Update: No.97 - Certificate of Accreditation 2009/01 for the The Hebel Panel Cladding System

A new cladding system has been approved for use on timber framed residential and light commercial buildings.

The Department of Building and Housing issued Certificate of Accreditation 2009/01 for the Hebel Panel Cladding (HPC) System on 15 April 2009.

The HPC System was accredited under the provisions of Part VIII ‘Accreditation of Building Products and Processes’ of the Building Act 1991.

This means the accredited system must now be treated as a certified product under the Building Act 2004 (see section 432(3)).

Certified products must be accepted as complying with the Building Code provided they are used in accordance with the conditions of the Product Certificate (see section 19(1)(d)).

In this case, the conditions require adherence to:

• OPUS Central Laboratories Appraisal 2009/10, dated April 2009, Hebel Panel Cladding System.

This Appraisal, in turn, requires adherence to:

• Hebel Supercrete Panel Cladding Design Manual Part 1 The Hebel Panel Cladding System, identified as HPC 2009/1.

The Certificate of Accreditation is notified on the Department’s website (see Current product certificates register). The Appraisal and the Design Manual Part 1 can be downloaded there.

It is important for those wishing to use the HPC System, and building consent authorities checking such proposals, to be fully conversant with these documents and ensure all their requirements are met.

Description of product and scope

The HPC System is a 75 mm thick, autoclaved aerated concrete wall cladding, fixed to steel battens over timber framing, with a painted textured finish.

It is for use on residential and light commercial timber framed buildings on concrete foundations, within the scope limitations of Paragraph 1.1 of Acceptable Solution E2/AS1 and where the details of the Design Manual Part 1 are used.

The former limits the use of the HPC System to buildings designed to NZS 3604: 1999 “Timber Framed Buildings” (including Amendments 1 and 2). The latter places limitations on the building shape, and provides required details, including those at external joinery, penetrations, movement control joints, and the junctions of the Hebel Panels with the concrete slab and the roof soffit.

Within these constraints the system can be used anywhere, irrespective of the building’s E2/AS1 risk matrix score.

Building Code compliance

The HPC System has been appraised and accredited as meeting Building Code clauses B1 ‘Structure’, E2 ‘External moisture’, F2 ‘Hazardous building materials’ and B2 ‘Durability’.

The specific performances complied with are as given in the Appraisal.

Different to the claddings of E2/AS1

The HPC System has fundamental differences to the claddings of E2/AS1.

Firstly, autoclaved aerated concrete is not a material covered by the acceptable solution.

Secondly, although the Hebel Panels are on a cavity, the cavity is not drained and ventilated but instead is closed in and effectively sealed.

The panel detailing along with minimum eave widths provide primary weather protection. A secondary means of weather resistance is provided by the absorption characteristics of the Hebel Panels, where moisture or condensation is absorbed into the back of the panel then released at the surface to the outside air by vapour diffusion.

Windows, doors and other penetrations through the HPC System are fully sealed to the Hebel Panels and have specially designed back flashings, to direct any water that may pass through the cladding at the penetration to the rear face of the panels, where it is released as vapour.

Certain work performed by Hebel trained and certified people

The HPC System relies on Hebel trained and certified people, namely the Hebel Supercrete Distributor, the Hebel Supercrete Panel Installer and the Supercoat Coating Applicator.

The Hebel Supercrete Distributor is responsible for designing the support batten layouts and for ensuring the metal components supplied for the particular building concerned are of the appropriate material and corrosion protection. The Hebel Supercrete Distributor also carries out quality assurance inspections at various stages of the work.

The Hebel Supercrete Panel Installer and the Supercoat Coating Applicator perform the work described below under ‘Building work’.

Components of the HPC System

The components of the HPC System are in part supplied by the building owner and in part by the Hebel Supercrete Distributor.

Components supplied by the Hebel Supercrete Distributor are installed and applied by the Hebel Supercrete Panel Installer and the Supercoat Coating Applicator.

Building work

There are three stages to the installation of the HPC System, namely the work performed by the building owner; the Hebel Supercrete Panel Installer; and the Supercoat Coating Applicator. The work involved in each stage is described fully in the Appraisal and Design Manual Part 1 and is briefly discussed below.

The building owner is responsible for completing the building work to a stage where the Hebel Panels can be installed. This work comprises the concrete slab, timber framing, wall wrap finished to all openings, installation of external joinery, meter boxes and services along with certain DPC (damp proof course) flashings.

The Hebel Supercrete Panel Installer installs the Hebel Panels ready for the application of the coating system. This work comprises the cavity battens, base angles, Hebel Panels including finishing DPC flashings around joinery, meter boxes and penetrations and movement control joints.

The Supercoat Coating Applicator applies the Supercoat Coating System along with backing rods and sealant around external joinery, meter boxes and penetrations. The coating comprises a sealed plaster system finished with an acrylic paint.

Maintenance

The maintenance requirements for the HPC System are set out in the Appraisal.

The owner must conduct regular cleaning and inspections of the surface as well as maintaining ground clearances.

Any problems detected with the cladding must be notified to trained Hebel personnel, for them to remedy. After five years the Hebel Distributor will conduct its own independent assessment of the system to ensure satisfactory performance.