Resene Popular Paint Systems – exterior timber: training notes
This web page is an edited version of the Resene Best System Selling training notes provided to Resene staff and is provided to enable you to gain a greater understanding of the substrates and paint systems you may encounter in your decorating project. It is impossible to cover all decorating scenarios in a single document, so if you are in doubt about any aspect of your project please contact Resene for assistance.
Select the timber surface you will be painting from the list below to view how to prepare and finish the surface.
Preparation & finishing flowcharts
Note: Refer to the PDF flowchart for a visual of the steps below:
Ensure the surface is clean and dust free
Prime using Resene Quick Dry Primer
Fill any nail holes and gaps, spot prime with Resene Quick Dry Primer
‘Use paint colours with a light reflectance value of 40%-100% to meet the 50 year durability requirement of the NZBC to prevent potential problems such as face checking. The use of ‘Resene Cool Colour Technology’ can increase the range of dark colours (LRV <40%) which can be used on the substrate and may be acceptable to the local Territorial Authority as an ‘Alternative Solution’.’
Shadowclad is a form of plywood and behaves in a similar manner. It is manufactured by Carter Holt in Australasia. Most commonly it is designed to look like rough sawn vertical timber – it is promoted as being suitable as a bracing board as well as cladding. Typically flathead galvanised nails are used to fix the sheets and are simply painted over.
Bracing refers to how a structure is stabilised against movement in strong winds and earthquakes.
To comply with the NZ Building code Shadowclad must be painted or stained and not left to weather. Marine ply can however.
It readily accepts paints and stains although due to an anomaly in the NZ building code when it is stained (with Resene Woodsman for example). It doesn’t meet the bracing standards and additional bracing (and cost) is needed.
The most common form of plywood used exterior is Marine ply. Construction plywood is also frequently used but typically as a base for a cladding such as vertical Cedar boards and polystyrene - usually to improve bracing.
Plywood and Shadowclad are manufactured from alternating thin layers of layered timber that are then glued together. The top layer is likely to split or check when first exposed to moisture and heat (a rainy day followed by a sunny day!). This will happen regardless of whether it is painted or stained first and is not a board fault.
We recommend that either it is deliberately wet and allowed to check (allow approx. 24 hours) and then primed and painted - applying a third coat to the checked area or painting it straight away and allowing for a third coat to be applied at a later date once it has checked.
The very best but hardly used paint system for ply is Resene X-200. For its crack filling and high build properties.
A roller is an ideal way to paint plywood and the face of Shadowclad.
The statement above is from the Resene Specification system for Shadowclad and is included as a note to point out the requirement for light reflectance values over 40% unless Resene Cool Colours are used and the local council accepts the change.