Applying the first top coat before installation can save time later and will assist in protecting against moisture uptake during the construction and finishing process.
For weatherboards it is recommended that at least the top 50mm is top coated (the area under the lap) prior to installation. This will prevent shrinkage lines showing through if the board expands or contracts as a result of climatic change.
The primer will not protect against moisture uptake, which can result in dimensional swelling.
If swelling or distortion of the timber is evident, the product must be given time to dry out and return to its equilibrium moisture content and manufactured dimensions before any top coats are applied to avoid shrinkage lines.
This applies especially to weatherboards and fascia.
All end cuts, notches, rebates and drill holes must be resealed with a suitable end-sealing product such as Tanalised® Enseal Clear.
Prime all nail holes with a suitable premium exterior wood primer and fill with an exterior grade wood filler.
Sealants must not be relied upon for primary weather protection, they are used to assist with weathering at joint and laps only. All filled areas must be spot-primed prior to top coating.
It is the painter’s responsibility to ensure all surfaces are correctly prepared prior to painting including ensuring that the primer is well-adhered to the timber substrate and that all surfaces are in a suitable condition before top coating.
Select a premium quality house paint that has a Light Reflective Value (LRV) of 45 or higher and a gloss level of 10 per cent or more.
Timber is a natural product and resin is a natural constituent of all timber. Timber painted in dark colours (LRV less than 45) may produce resin bleed.
The LRV of a colour indicates the amount of light and heat that a colour will reflect. Black has a reflectance value of almost 0% and absorbs almost all light and heat. The surfaces are consequently very dark and can get very hot. In contrast, white has a reflectance value of almost 100% and keeps a substrate cool.
Envira weatherboards and components are machine coated on all faces with an alkyd true primer ready for two top coats of premium quality house paint within six weeks of the product being installed.
Irrespective of when the top coats are applied, ensure all loose material and dirt is removed. Some sanding and spot priming may be required.
Paint must be applied with the necessary equipment and experience under the appropriate environmental conditions to ensure that the potential of the paint system is maximised.
All painted exterior surfaces should be washed at least once a year—do not use a water blaster. Up to 10 years can be expected before a repaint is required, however, this will depend on the colour, type and quality of the top coat and the preparation of the surface prior to applying the first top coats.
To ensure timber products achieve the durability and long life you expect, it is essential that a protective paint system is maintained in good condition and not allowed to deteriorate.
Visit the 'Caring for your paint' page on the Resene website for addition advice:
All new buildings will ‘settle’ and during this process the integrity of the paint system, no matter what type of substrate it has been applied to, may be compromised resulting in minor touch up work being required. If re-priming is necessary, use only a premium quality primer and the original top coat paint for touch up work.
Like washing your car, cleaning your house will help it maintain its good looks for much longer. Airborne contaminants, including salt deposits, which settle on your paint film, can attack the surface and cause premature breakdown. Annual washing of your home will help maintain the fresh appearance of your paintwork.
The presence of moss, mould and lichen will hold moisture on the surface longer, promoting further growth of these organisms and increasing the risk of damage to the coating and substrate. As with any painted surface, regular inspection and immediate repairs to areas of flaking or cracked paint are essential and will stop the entry of moisture into the substrate.
Particular attention should be paid to areas of high weathertightness risk such as around windows and doors, checking that flashings and sealants are in good condition and performing as required. Repair immediately if the building weathertightness has been compromised.