How to install timber weatherboards?

When installing weatherboards right components and correct installation methods are critical. There are specific cladding systems guides, for the correct installation of weatherboards to achieve long life, durability and stability. these are written to ensure that they will meet all technical requirements on the NZ building code. The individual installation manuals are available on our downloads page,  

Download full installation guide here 

CertClad Weatherboards

CertClad is the brand name for ITI Timspec's certified cavity-based weatherboard cladding system. These are tested and assessed in accordance with the requirements of NZ building Code Clause E2/VM1 by a third-party organisation and have attained CodeMark certification.

What is CodeMark certification?

CodeMark is a voluntary product certification scheme that provides an easily understood and robust way to show a building product meets the requirements of the New Zealand Building Code. A product can be a building, construction method, building design or a building material. CertClad systems are CodeMark certified and are approved to be used as a partial or full cladding system for residential or small scale commercial building types. 

Read more on CertClad here www.certclad.co.nz/

Pre-Installation of Weatherboards

On-Site Storage and Handling

  • Care must be taken to ensure that the timber and accessories are kept clean and dry, and are not damaged whilst in storage awaiting application.
  • Extra care must be taken while handling timber to ensure that it is not damaged.
  • Timber is to be stacked on flat level bearers/dunnage that is maximum of 900 mm apart at least 100 mm off the ground.
  • Timber should either be stored inside an enclosed building or covered with an additional waterproof layer and protected from elements when stored outside.

Important Notice: 

  • Accoya Weatherboards should not be installed if their moisture content is 12% or more.
  • Radiata Pine Weatherboards should not be installed if their moisture content is above 18%.
  • Western Red Cedar Weatherboards should not be installed if their moisture content is above 18%. 

Docking Out Defects

Before coating or installing boards, check for any defects that may require docking out.

All docked ends, any exposed or bare timber of stained or painted weatherboards will require end sealing with a minimum of one coat of primer or stain, double priming or coating is recommended. 

Priming and Sealing

Apply the first coat of stain or primer to all sides and edges of the weatherboard prior to installation to ensure that all timber is envelope sealed. It is critical that the timber is at the correct moisture content level prior to priming. Remember that all docked ends will require priming as noted above. Follow the coating manufacturer's directions and ensure further coats are applied as required. All relevant sections of standard AS/NZS 2311: 2009 (Guide to the painting of buildings) must be adhered to. 

Note: It is usually easier to order weatherboards to arrive on-site pre-primed /pre-coated.

This will ensure weatherboards are primed, and or coated with the correct products to exact levels and the timber is at the correct moisture content.

Site Preparation - Structure and framing

New Zealand Standard 3604

Generally, the timber framing must comply  with NZ3604 (2011) (Timber-framed buildings). However, where specific engineering design is required, the framing shall be at least of equivalent stiffness as mentioned in the framing provisions of NZS 3604 (2011)

Layout

For Horizontal weatherboards, studs must be spaced at a maximum of 600mm, centre to centre.

For vertical weatherboards dwangs (nogging) must be spaced at a minimum of 400 mm and maximum of 480 mm, centre to centre. Studs and dwangs must form a flush plane for cavity battens and weatherboards to be fixed. 

Additional framing may be required at soffits, corners and penetrations such as window and door openings to support the installation of battens. 

Moisture Content 

The moisture content of the framing must not exceed 18% at the time of fixing the weatherboard because problems may occur later due to excessive timber movement if framing is too wet. 

Building Underlay

Building underlay must comply with properties stipulated in NZBC Clause E2/AS1 table 23 (Properties of roof underlay and building underlays) or equivalent proof of compliance to NZBC.

Installation

Install the building underlay directly over the framing i.e. under the cavity battens. Building underlay to be installed in accordance with underlay manufacturer's specification, or in accordance with conditions set out in NZBC Clause E2/AS1.9.1.7.2.