Having decided to use oak for a natural flourish outdoors, can you use planed timber outside? Wood is a natural choice as its warm, organic look complements the existing colours and textures of a garden. But, if softwoods are used outside, they will need chemical treatment to preserve them from the ravages of the elements. Having a porous texture, they are prone to moisture penetrating the wood, leading to rot and decay. They are also more prone to insect and fungal attack, reducing the lifespan of any structures. Chemical treatment also increases the environmental impact of the production process.
This makes hardwoods the perfect choice for exterior timber features. However, even oak will eventually change in appearance as the sun and to a lesser extent, rain, affect it.
Reasons for Using Planed Oak Timber
1. Aesthetic Choices
Even at first glance, planed oak timber will make any outdoor structure ‘pop’. Planing works to expose the prominent grain pattern of oak that makes it so desirable for feature pieces. For modern buildings, the use of planed oak gives a contemporary look to any extension while juxtaposing the traditional, rustic material. For free standing pieces such as gazebos, the sharp regular profile increases their prominence as a feature.
Planing gives a completely smooth, splinter free finish that is far safer than rough sawn timber. For any surfaces coming into contact with bare skin, this makes planed oak timber a must. Balustrades, fence tops or balcony railings will regularly have hands run along their length, making splinters an obvious danger. Similarly, decking, furniture, stairs and oak planks used for balcony flooring will all be much safer if planed oak is used.
3. Ease Of Use
For the DIYer, planed oak has a number of advantages over rough sawn timber. As the timber is already finished, it can be used immediately with no need for sanding, saving much time and effort. Planed oak wood will fit flush together, giving a sturdier structure straight away. For flooring, this makes building far easier and gives a much neater result with no extra effort. Finally, applying finishes to rough sawn timber is difficult and largely aesthetically pointless but easy to achieve with planed wood.
Types of Planed Oak
There are three different types of planed timber, each suitable for a variety of uses depending on the number of planes visible. The more sides that are planed, the more expensive this becomes, so it is worth being aware of the differences before buying. Luckily, the acronyms for these are short and their definitions easy to remember.
This stands for Planed All Round, where all four sides of the timber have been planed smooth. Obviously, this involves more production work, making this the most costly option. PAR timber is mainly used in structures where all four sides are visible, such as the support posts for gazebos. Open porches, covered gateways leading onto the property, solid oak fenceposts and newel posts and bannisters are also notable uses. Layered, overlapping cladding is best done with PAR timber as the wide and thin edges will be visible.
This is variously taken to mean Planed Single Edge or Planed Square Edge, but the meaning is the same regardless. As the name suggests, only one side (usually one of the wider surfaces) has been planed. This is ideal for cladding, decking or other floor surfaces where only one side can be seen. It also gives a smooth, splinter free floor surface where humans or pets will be walking.
Less commonly seen than the preceding two types, PBS stands for Planed Both Sides. Both wider surfaces have been planed smooth with the two narrow sides left rough and unfinished. It is commonly seen as floorboards in raised balconies or verandas where the timber can be seen from above and below. The narrow edges can remain unfinished as they will lie tightly together after building and not be seen. This also makes the timber itself cheaper to use than PAR as it is easier and therefore less expensive to produce. PBS timber is also good for cladding open carports or oak garages as the wall surface will be visible both inside and out.
Treating Planed Wood
One of the main practical reasons for using oak outdoors is its resistance to the elements and attack by pests. Planing itself will not alter these properties and planed oak is just as durable as rough sawn. Over time, sunlight will affect the appearance of oak, causing the colour to change from a honeyed light brown to a silver hue. This can make the grain difficult to see Excessive exposure to rain can cause a black build up on exposed surfaces as the tannins in the oak react to the water. While neither of these effects cause any physical damage to the timber, some owners prefer to retain the original colour.
1. Preserving the Original Colour
This can be achieved by applying one coat of clear wood preservative, followed by two coats of UV protection oil. The oil functions in a similar way to sunblock on human skin, blocking ultraviolet light that affects colour. It should be noted that even clear preservative will cause some darkening of the wood. Applying a thin coat of water to the oak timber will give an idea of the tone after application. Some UV oils also contain biocides to offer further protection from wet and dry rot.
2. Protecting Silvered Oak
Following a coat of clear preservative, apply three to five coats of Tung oil. This will not protect the oak wood from UV light but as it is already silvered, this isn’t important. Exterior oak in Britain should not need this treatment as the weather and climatic conditions are not severe enough to damage the wood.
3. Removing Blackening
This can be from reaction to rainwater or fungus on the surface of the wood. The first step should be a scrub with a fungicidal wash followed by scrubbing with wood reviver gel. The wood reviver will usually contain oxalic acid to bleach the wood which can be harmful to humans. Always consult the safety data sheets on the manufactures websites and follow all safety advice.
Hardwoods group are specialist European oak suppliers with a huge range of wholesale oak timber of all types. We can supply rough sawn oak or all types of planed oak to suit your latest outdoor project. Contact us to discuss your requirements, we will be happy to help.
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