Bendigo Hospital by Silver Thomas Hanley in collaboration with Bates Smart │ Photography: Shannon McGrath / Peter Clarke
Nothing quite compares to the inherent beauty, character and warmth of timber. Combining its aesthetic appeal with sustainability attributes and thermal benefits, it’s no wonder timber is one of the world’s most loved building and design materials.
Coatings and finishes can not only help achieve and maintain aesthetic requirements, they’re also important in maximising the service life of any timber design feature or element.
Timber finish types
There are generally 4 types of timber finish distinguishable by respective levels of pigment.
With high transparency, clear coatings allow the natural colour and character of the timber to be expressed with a matt, satin or gloss sheen. It’s important to note that clear coatings can impart a warmth to timber which is usually accentuated if using an oil based product. Although many clear coatings do contain UV absorbers, they will generally not last as long as more pigmented finishes which provide better protection against UV exposure. For exterior applications, it’s also important to note that clear finishes will require more frequent maintenance and recoating.
An oiled finish is ideal for enhancing the natural appearance of timber. Oils typically contain a lower level of pigment compared to a stain and will generally help bring out the natural beauty of the timber as opposed to changing the colour. Oils can be water based or oil based and vary significantly with respect to durability. A water based oil product such as UltraDeck for example, can last up to 3 times longer than a traditional oil based product. From an aesthetic perspective, oil based finishes tend to penetrate into the timber more than water based products but consequently, require recoating more frequently.
Timber stains offer a greater level of pigment compared to oils and are ideal for adding deeper, richer colours and tones to timber features. Due to the higher levels of pigment, stained finishes will typically outlast clear or oiled surfaces under the same conditions making them comparatively more practical for exterior limited-access applications.
Opaque or paint finishes provide solid colour and excellent protection against UV. Timber opaques will generally hide the timber grain and reduce textural effect but are available in a wide range of colours for both interior and exterior applications.
Timber that’s exposed to the elements will always weather and eventually show the effects of UV, rain, wind and dirt. In some instances, the weathered or silvered off appearance is a desired effect and care should always be taken to specify the most appropriate species depending on exposure levels, to maximise design and service life. Factors that may adversely affect the appearance or visual consistency of timber left to weather naturally, are differential exposure orientations, overhangs, mould and dirt.
There are many factors that will affect the lifespan of timber finishes. Surface preparation, spread rates/film build, moisture ingress, wear and UV intensity are all things that can impact the performance of a coating. We recommend annual inspections to check for signs of wear or degradation and regular cleaning for trafficable surfaces to ensure there is minimal build-up of dirt and grit from shoes.
During inspections, any minor damage should be touched up and where patchiness or thinning of the coating is observed on larger areas, a full recoat should be applied following the manufacturer’s instructions. Addressing signs of wear well before the coating or timber deteriorate significantly is always recommended.
There are many ways to maximise design life and minimise the extent of maintenance.
- Eaves, overhangs and soffits
An effective way of reducing maintenance requirements is by incorporating design elements that limit the timber’s exposure to sun and rain such as eaves, overhangs and soffits.
- Type of finish
The more pigmented a finish, the better protected the timber will be against UV. Additionally, water based finishes will tend to last longer than oil based finishes (assuming comparative levels of pigment and other conditions).
- Timber profiling
Sharp edges and corners can lead to coating weak spots. Arrised or rounded edges allow better coverage of the coating, reducing the risk of premature failure and moisture ingress.
- Factory application
The quality and consistency of application is key to the performance of any finish. Insufficient coverage or leaving end grain, undersides and back faces uncoated can ultimately reduce surface coating integrity and effectiveness. One of the best ways to ensure longer term coatings performance is through factory application. Timber finishes applied in a factory environment are generally applied under controlled conditions which can help ensure correct spreading rates. Factory application can also help ensure the timber is coated on all sides, which can provide better protection than timber only coated on one side. The added benefit of factory applied finishes is the reduced on-site labour requirement saving builders time and money.