Natural weathering, SiOO:X or painted: a guide to timber cladding finishes
When selecting timber cladding, consider the final aesthetic you are trying to achieve. Do you like the weathered look? Are you happy to wait for it to weather naturally, or do you want it to develop more quickly? Would you like a coloured finish? Do you prefer translucent or opaque? If you need some inspiration Russwood’s Pinterest boards can be a great place to start.
All species of timber will eventually weather when exposed to the elements so bear in mind that if leaving your timber cladding uncoated, the appearance will change over time from its original colour to a silver-grey tone. Weathering is a natural and healthy process and shouldn’t be confused with fungal decay, which can sometimes be seen in cladding which has been incorrectly installed.
Location, building design and species can all have an effect on how quickly and evenly timber cladding will weather. In areas of high rainfall some timber cladding installations can turn grey quite quickly, whilst in drier areas the process is likely to be slower. The form and shape of a building also influence the impact that wind-driven rain will have on it. For example, buildings without eaves tend to get wettest at the top, particularly at the outer corners, so this may result in these areas weathering more quickly than other parts of the wall. If there are eaves, then uneven weathering can occur as rain will be unable to reach the areas under the eaves.
To maximise the chance of even weathering on your facade consideration should be given to cladding arrangement. Open rainscreen profiles such as Russwood’s RW014 tend to weather more uniformly as air is able to circulate around the whole cladding board allowing the timber to fully dry out in between wetting cycles.
A weathered look without the wait
If you want to achieve a weathered look without the wait, this can be achieved by the application of SiOO:X, a Swedish timber impregnation system which uses advanced silicate technology to provide a consistently weathered appearance at an accelerated rate – typically starting to develop around 10-16 weeks.
Applied in two parts at our in-house coating facility, SiOO:X Wood Protector penetrates deep into the fibres of the cell walls where it forms a network of silica crystals, creating a barrier which is bonded to the surface. A further application of SiOO:X Surface Protector is then applied which binds with the Wood Protector and prevents water penetration.
Following application, SiOO:X cures by reacting with atmospheric carbon dioxide and moisture to form an insoluble and flexible silica network which toughens the surface of the timber. In addition to the protective benefits gained, as the mineral silicate cures it will start to turn the timber a beautifully even driftwood colour.
While the curing of SiOO:X Original takes 10-16 weeks to develop its driftwood-like appearance, two pigmented versions – Mid Grey and Light Grey – have been developed to give a more immediate and long lasting colour to the timber. SiOO:X Mid Grey gives a soft, muted grey colour while the Light Grey version gives the light driftwood colour to the timber. After 2-3 years, the timber is fully cured and a final colour is reached. The result is a consistent weathered tone, achieved years faster than with natural weathering.
If you’re not keen on the naturally weathered look, a painted finish might be more to your taste. We would always recommend factory coating as opposed to on-site paint application to ensure a more durable, consistently applied flawless finish. If you are considering coating on-site, remember to take into account that labour, painting equipment and scaffolding (if required) costs will be incurred, plus the potential cost of project delays due to adverse weather conditions.
Modified timbers such as Thermopine® and Accoya® are particularly suited to coating, as less substrate movement means a paint coating can last up to three times longer than when applied to non-modified timbers. Resin bleed is a common issue when coating unmodified resinous timber species, particularly in dark colours which are proven to absorb more heat. The thermal treatment process used in producing Thermopine® eliminates the issue by “burning off” resin so that it cannot exude in due course.
You can browse our standard colour guide to see our recommended RAL (opaque) and Teknos (translucent) colours. Bespoke colour options are available in addition to our standard colour range – you can advise us of the RAL number or choose from Teknos Forest Inspirations (browns, greens and yellows) or Cotswald Collection (pastel shades).