Wooden Deck – A Crash course on all you need to know

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Wooden Deck – Have you ever wanted to build your own wooden deck, but you have no idea where to start? Want to buy timber for your wooden deck project, but have no clue on which ones are the best option? Not to even mention what the timber sizes must be!

Do not fear! In this article, you will find all the information you may need about wooden decks, in just one place! Starting with the history of the wooden deck(you will be surprised how it started) up to what the size recommendations are for the timber that you will use. Let us get started!

History about the Wooden Deck

Historically the softwoods that were used for decks ages ago, were logged from old-growth forests. This includes Atlantic White Cedar, Redwood, and Western Red Cedar. Atlantic City ( in New Jersey, United States of America) was the first to build a coastal boardwalk in the United States, that was originally constructed of Atlantic White Cedar. However, it was not long before the commercial logging of this type of tree and the clearing of Cedar swamps in New Jersey caused a decline in the availability of wooden decks. Atlantic City and New York City then both switched to Western Red Cedar. By the time it was the 1960s, Western Red Cedar from the US was declining due to the term over-logging. In Western Canada (British Columbia) more expensive Western Red Cedar became available, but at the same time, pressure-treated pine also became available for wooden deck building.

What is a wooden deck built with?

Wooden Decks are often built from pressure-treated wood. Pressured treated wood is durable and holds up to wet and icy weather conditions. However, pressure-treated wood is known to be treated with chemicals that have been known to be toxic. It is also important to know that both the softwoods and hardwood decks will need to be finished after installation by using either an oil or a varnish to prevent the wood from weathering, wear, mold, algae, and wood-boring insects.

In general, a hardwood that is used for decking comes from tropical forests. Most of the logging that is taking place to produce these woods, especially teak, mahogany, and ipê, is occurring illegal, and are outlined in numerous reports by environmental organizations such as Greenpeace, Friends of the Earth and Rainforest Relief. The United States’ tropical wood imports are rising, partly due to the high demand for wooden decks.

What does a wooden deck normally include?

Some residential decks have been known to offer spaces for cooking, dining, and seating. The cooking areas are ideally situated near the patio door to be out of the way of any foot traffic. Dining spaces will include enough of movement space for a patio table and dining chairs. If any deck space is left available, homeowners usually fill those areas with couches and benches to feature a seating area on the deck.

Construction of a wooden deck

A house deck is a raised wooden platform connected to the main building, often accessed through doors or a ground-level stairway. For safety, it has a railing to prevent accidental falls. Wooden decks are versatile, allowing construction on steep or rough terrain. Canopies or pergolas can be added for sunlight control. Two common construction types are post and beam, anchored to the ground, and cantilever, extending from the house wall. Proper waterproofing and flashing are crucial for safety with cantilever decks.

Wooden Deck

Did you know…

In the United Kingdom, the various ban on smoking in buildings was expected to lead to an increase in the use of the wooden deck for outdoor spaces where the smokers can gather outside.

Popular Wood used In South Africa for a Wooden Deck


Balau (Shorea/Dipterocarpaceae)

Well-known hardwood from Malaysia. Also common in Indonesia and the Philippines and is now used worldwide. It is deemed to be naturally very durable. Hard, very dense and tightly grained. It does not respond well to treatment and is often used in areas that warrant little or no maintenance. Color ranges from light brown to “yellowish” brown, gradually turning darker brown (distinct from the paler sapwood). Over time, without being oiled, it will turn to a silver-grey color.

Considering the density, it is relatively easy to machine and ply. However, working it with hand tools does present its challenges. It does not contain silica. Resin pockets occur, so there will be resin build-up on cutting equipment. Any contact with ferrous metals will leave a black “ink” marking, but they will eventually fade. Pre-drilling is advisable when nailing. Stainless steel screws are recommended. Balau can be painted and polished (staining not considered necessary). It is not regarded as suitable for steam bending. You must allow for some tolerance to natural shrinkage.

The level of durability dependents on the quality of the Balau selected. There have been cases in South Africa where Balau has performed poorly against fungal attack. This happens due to frequent wetting and poor maintenance of water-repellent wood sealers.


Massaranduba (Manikara Bidentata)

This “red-brown” timber from South America (mainly Brazil), offers a rich, deep brown finish. It has a fairly straight grain and is available in long lengths. It has a light red color, changing to dark reddish-brown when exposed. A hardwearing timber, suited to both coastal areas and regions with extreme climates. The sap is used to make natural latex, an indication of its very high durability.

A very dense and slow-drying timber to prevent extreme checking. The wood can be worked with hand tools with somewhat of a blunting effect.


Garapa (Apuleia Leiocarpa)

Brazilian native with a given reputation as a very stable and strong timber along with an exceptional lifespan. This hardwood lasts well in most climates and fits in with the natural environment. It has a largely fine and straight grain with occasional wavy characteristics. The even coloring described as a yellow, honey or gold finish, takes on a red-brown hue when exposed. It will turn silver-grey over time if you leave it untreated.

Garapa is very durable and resistant to insect attack, rot, fungal decay and also fire. It does not require additional treatment. This wood has become a preferred choice among decking timbers. It is often compared to the darker and more expensive hardwood Ipê.


Ipê (Handroanthus/Tabebuia of family Bignoniaceae)

South American timber with clear all-heart, no knots, and no sapwood. Known as one of the hardest and most durable species in the world. Although revered for its beauty, the wood grain can vary considerably. The color ranges from red-brown, dark brown to olive-brown and sometimes have almost blackish tones or stripes.

Because it is very dense, the fire-resistance rating is very high. Natural resistant to rot and decay, insects, weather and movements. It requires no chemical preservative treatment. Although it can be sealed to maintain the natural color and beauty, it can also be weathered to a silver-grey.

WIth being extremely hard and dense, it is considered difficult to work. It has a high cutting resistance during sawing. Ipê also has a pronounced blunting effect on cutting edges. It is advised to use hand and machine tools that have carbide-tipped blades when cutting. The wood generally planes smoothly, but the grain can tear out on interlocked areas. It can be difficult to glue properly, so the surface must be prepared beforehand. The wood holds screws well and nut nailing does require re-boring. In general, Ipê dries, stains and polishes well.


Saligna (Eucalyptus saligna/Myrtaceae)

Generating from Australia, but is well-established, grown and readily available in South Africa. Saligna is of medium density and regarded as low to moderately durable. It requires regular maintenance (untreated sapwood can be at risk for borer attack). Described as pinkish-red, light rose-brown or very dark honey, this wood stands apart from the pale yellow sapwood. The grain is typically straight but with occurring interlocking. The texture is rather coarse, and gum veins are not uncommon.

Relatively easy to dry, Saligna also works fairly well. The wood can take nails and screws without undue difficulty and is easy to dress and fix. Saligna responds well to most finishes. In taking a good polish, it is popular in decorative applications that call for modern durability.


Zimbabwean/Rhodesian Teak (Bailkiaea Plurijuga)

Also known as Zambesi Redwood, it is one of the most often-used hardwoods in Southern Africa for both decking and flooring. With a fine texture and low natural luster, this timber has a very pronounced, straight-to-interlocked grain. It has a clear distinction between the paler pinkish-yellow sapwood and that of a medium reddish-brown coloring with common black flecks and streaks. Heavy, hard and rated as very durable, it has a good resistance to decay and abrasion. It is also resistant to preservative treatment. The sapwood, however, is susceptible to insect attacks such as powder post beetles (freshly cut timber must be processed and finished quickly).

Zimbabwean Teak has a high silica content which gives high cutting resistance (blunting cutting edges). The wood saws slowly, and has been reported to ride up over jointer knives. On the other hand, the wood yields great wear-resistance in service and it glues and finishes well.

Zimbabwean Teak

Merbau (Intsia Bijuga / Intsia Palembanica, Caesalpiniaceae family)

Known to be a bit more expensive, Merbau is another very dense, very stable and very durable option (also for flooring). Hailing from Malaysia, the texture is coarse but even with an interlocked grain that is mostly straight. It can occasionally be wavy and produce a ribbon striped effect.

It has a yellow-to-orange brown color when freshly cut, but becomes a darker red-brown upon exposure and with age. The coloring between boards has been known to vary noticeably. An interesting character is small yellow mineral deposits present throughout, which makes it quite distinguishable.

Sawing can be a problem because of gumming. The wood is known to split during nailing – making pre-boring essential. It offers resistance to shock loads. This wood does hold screws satisfactorily and glues, stains, polishes and finishes well.


Red Ironbark (Eucalyptus Sideroxylon)

This Australian native is considered ideal for our climate. With an extremely dense timber – estimated at roughly 1 130kg/m3. It is one of the few timbers that will not float. It is sought after for the exceptional outdoor lifespan, the strength, and durability it ensures. The wood is a deep dark-red to a red-brown in color, contrasting sharply to the pale yellow sapwood. The timber’s texture is fine and even with an interlocked grain. It is very suitable for external applications due to its durability and hardwearing nature.

The timber dries slowly and is very hard to work, especially with hand tools and where fine detailing may be required. You must take care to minimize surface checking. Reports show that the tree is prone to “piping”, meaning hollow forms in the center of the trunk. This impacts the yield and the sectional sizes of sawn timber.

Red Ironbark

Meranti (Shorea)

Imported mostly from the Philippines, this durable light hardwood varies considerably in color from light pink/light brown to a dark reddish-brown. Even a reddish-purple/purplish brown and white resin streaks are not uncommon. (In some mixed species, coloring leans towards yellow-brown). The sapwood is lighter and often contains a grey undertone. It has a coarse but even texture with medium to large pores and interlocked grains.

Readily available, this timber comes in long lengths and in thick planks, which increases its versatility. Reported as moderately durable (or lower) in its resistance to decay. It is susceptible to insect attacks such as termites. The wood is mostly easy to work with, with interlocked grain occasionally presenting challenges during the planning. It glues, stains and finishes well. Note: Some varying species (there are differences between White Meranti, Yellow Meranti, and Red Meranti) can blunt tools due to silica being present in their wood.


Karri (Eucalyptus diversicolor)

Slow-growing hardwood that is native to Australia and with distinctive red hues in an interlocked grain. Karri timber presents with an attractive golden appearance. The wood can vary from reddish-brown to pale pink, while the sapwood is a creamy white. Suited to areas with a stable climate, and moderately coarse in nature. It is also moderately durable with the accompanying resistance to preservatives and other treatments. The sapwood is vulnerable to borer and termite attacks, but it is naturally resistant to decay.

Patience and care are needed in the drying process to prevent surface checking, cracking and warping. It is difficult to be worked with hand tools. Karri finishes fairly well and accepts stains and polish without undue problems. However, it does not accept paint well. In addition, machining and surface preparation must be done right before gluing occurs.


Softwoods (From Gymnosperm, or Evergreen Coniferous Trees).


Commonly grown for commercial purposes. South African plantation-grown pine is regarded as non-durable and susceptible to damage from insects and fungi. Pine is ideal for preservative treatment. Its durability only increases when correctly treated at a primary timber treatment plant using industrial impregnation processes. These processes include vacuum/pressure processes. Pine continues to be a very popular choice for decking. Despite not being as intrinsically durable as comparable hardwoods, it is very cost-effective and holds a charming appeal for many end-users.

When treated to the correct hazard class, pine can be utilized in both the decking and deck substructure components. Pine has a medium and relatively uniform texture. Resin, canals or ducts can appear as fine, brown lines on longitudinal surfaces. Pine works well with both hand and machine tools. Nail holding is good, gluing is satisfactory, and it also finishes well, with the surfaces providing a satisfactory finish.


Wooden Deck 101

Why should you have plans drawn up for your wooden deck?

This one is very simple. A local council usually has the final say and they can ask to see any of your plans as, well as the engineer’s certificate. If you are in the market to build a wooden deck for your home, you should be aware that if you go through with the building without any plans and later want to sell the property, you will end up having to submit plans. Most councils now require that the plans are up to date prior to the release of the rates clearance certificate.

Another important aspect that you should keep in mind, is that most of the deck’s collapse. Believe it or not, there are many every year in South Africa. These collapses usually occur due to when the wooden deck is overloaded (such as a New Year’s get together). It even occurs when heavy rain washes out one of the support beams. Wooden decks that have not been designed properly can even be lifted off their posts during a storm or very strong winds. You as the homeowner will then be liable for any damages, injuries or even death that resulted from the failures if you did not engage with an engineer to certify the design and construction. Engineers carry indemnity insurance that will cover most of these types of incidents.

So, do it the legal and right way and get that plans drawn up from a professional and get a certified engineer for the construction.

Legislation governing timber deck construction:

The legislation stipulates that treated timber in South Africa must adhere to national and compulsory specifications. They must display the hazard class (A metal marker for treated poles and an ink stamp for sawn timber). A rating system, that is similar to those used internationally, is used in South Africa. In this system, the higher the hazard number, the greater the risk the wood can be exposed to. Products such as CCA and Creosote are effective heavy-duty preservatives and are able to protect in all classifications from H2 to H6. Others, such as LOSP preservatives and borates, have only a limited number of useful applications. They are associated with mainly dry interior end uses.

In South Africa, timber structures must be designed and built in accordance with the South African National Standards (SANS) 10163, which governs the structural use of the timber and SANS 10082 for the “Timber Frame Building”. An engineer would always make use of the SANS 10163 on a timber decking project.

SANS 10082 is the code of practice for any timber structures and you should make sure that your constructor has a copy of this document, as well as SANS 10043 (Solid Wood Decking) on hand. If not, do the right thing and hire another contractor. The National Building Regulations must also be strictly adhered to when you are constructing a deck or any other structure. This will refer to the designer, the builder and the engineer to the relevant code of regulation for the correct execution of the project.

Did you know…

A wooden deck that is more than 1.5m off the ground should be designed by an engineer with experience in timber construction?

High Constructed Decking

Treated structural timber for a wooden deck

Deck sub-structures are usually referred to as the framework or “skeleton” of the deck, which is always visible. These wooden deck sub-structures are built with CCA-treated Pine due to the cost of naturally durable hardwoods. Pine that is exposed to the elements of the earth should be CCA treated to a Hazard Class 3 (if above the ground) and a Hazard Class 5 (if it is in contact with the ground, which results in most of the poles). The CCA treatment is done in a pressure vessel that is on the sawmills ground, and these poles are something that cannot be painted on. Any cutting or planning of the poles on-site should be touched up with a remedial timber preservative suitable towards the timber. These timber preservatives include Enseal, CuGard 20 or similar.

Unfortunately, many wooden deck constructors do not coat the sub-structures of the decks, especially if it is not visible to the eye. This is a shortcut approach. The wood beneath the deck will often remain damp for long periods of time after heavy rainfall. This makes it the ideal environment for the growth of fungi (which will erode or eat the timber away).

Construction no no’s…

Timber poles should never be encased in concrete and should rather be supported on a pre-cured concrete foundation pad. This pad should be on a firm piece of ground or should be erected with a concrete “collar”. This will allow for sufficient water drainage at the base of the poles. The support posts should not be supported on fill at the edge of a new embankment, which will subside with time.

A serious and huge mistake is being made from time to time by wooden deck refurbishers. This mistake is that they remove the old wooden deck slats, and immediately fix the new ones onto the old timber structures. The screw holes left behind are an ideal catchment for water. This will help advance rotting in the structure. These screw holes should be filled with a waterproof filler. The top of the joists should be coated with supplemental and remedial brush-on preservatives. Once they are dry, at least two coats of a good quality exterior wood sealer should be applied.

Please keep in mind, wood is an organic material and parts of their charm are that every piece is different. The markings, small cracks, and checks are fine, as long as they do not affect the safety and structural integrity of the wooden deck. Very large, unsightly cracks that are visible, or those that can collect water, must be avoided at all times if possible.

Metal fastening systems

When you are using metal fixings, they should be galvanized, stainless steel (if possible) or the screws must be Kal coated. The screws should be countersunk in hardwoods. The holes should be filled with wooden plugs, epoxy or a suitable waterproof wood filler. Do not, and I repeat, do not use regular wood filler for this application, as it will dissolve after the first heavy rain it gets.


The substructure (wood underneath the deck’s top planks) must not come into contact with the ground. Normally, the timber used for the sub-structure is treated to H3, which is not suitable for ground contact. If the timber is to make contact with the ground, then it should be treated to H4. However, most of all treated structural timber is generally treated to H3, unless specifically requested to be treated to a higher hazard class. In less dry areas, decking sub-structures can be treated to H3, but further inland, the decking sub-structures have to be treated to an H4.

All treated timber used for sub-structures must be structural stress-graded timber. This means it must be graded and certified to a minimum strength grade of S5. Structural timber is marked with a red stamp bearing the name of the sawmill it comes from. It also has an “S5” denoting the strength or the stress grade of the timber, as well as either the SABS or SATAS quality mark.

Did you know…

Components like decking slats and balustrades on a deck are often misread as non-structural, but they must be installed in a structurally sound way to ensure that they do not fail when a load is applied onto or against them.

Wooden Deck Style

When choosing your type of wooden deck, consider the following factors:

Weather conditions in your region

If you live in a place that experiences extreme weather conditions like rain or summer, you must choose something that is hard and durable. It must withstand such extreme weather conditions

The structure of a deck

Materials for a deck should be chosen according to the structure your deck will look like. If you are going to have a covered deck, you can choose something that is shiny and with a better finish. But, if your deck is open, your deck should be hard and rugged to cope with all types of weather conditions.

How much you want to spend (Cost)

This plays an important role when choosing the right deck that will succeed in all your needs. Normally, people prefer to get durable and long-lasting decks, which results in being available at a reasonable price.


Different types of decking require different types of maintenance. Some decking wood requires less care in the form of polishing and refinishing in comparison to others.

Deck Maintenance

Don’t know when to give your deck maintenance? The time period between the completion of a new deck and its first round of maintenance depends on a few factors. Those factors include:

  • location,
  • the extent of exposure to the earth elements,
  • what type of timber you used,
  • the type of coating your timber received.

Your deck should not be left longer than 18 months before it receives the first routine maintenance. A 12-month maintenance cycle is preferable. If the deck does not whether well before the 12-month mark, immediate action must be taken. When not taking immediate action, the lifespan of your deck will greatly be reduced. Handrails on your deck are the ones that endure the most wear and will need attention usually after just one year.

All the gaps that have been created over time, should be filled up with a waterproof filler prior to recoating. You should at least apply two coats of most products; if the deck has been sanded down to bare wood, then you would be required to apply three coats. People have been found to enjoy the silver-grey weathered look on their timber. This can only be achieved in most timber species by leaving them uncoated, but in reality, the uncoated timber’s lifespan will be reduced. Timber that is coated with a good preservative or sealant will always outlast an uncoated timber.

Not very wise…

It is not wise to let the maintenance contractor sand down the deck with an industrial floor sander if your deck is not in a bad condition. If they do, it will reduce the number of times the deck can be sanded. This type of sanding should only be done if your deck has weathered down significantly. For routine timber deck maintenance, sanding with a big belt sander is sufficient, and if your deck is in fairly good condition, an orbital sander will be the best option.

Points to consider when you want to hire a wooden deck contractor

There is a huge number of individuals in the market who are not qualified or experienced in the field of timber decking. You, as a homeowner, can make the best decision. Hire a reputable deck builder when you are in the projects of building a deck at your home. While decks are a great addition to any structure, you have to remember that they still are expensive. If there is even just one mistake on the contractor’s part, it can ruin the deck and will be very costly to repair it.

If you want complete peace of mind, hire a decking contractor who holds a membership with the Institute for Timber Construction South Africa. Not only will the contractor that you hired be well versed in the construction regulations, but you as the customer will have a professional body which you can refer to should the workmanship or materials that are used not be up to standard.

Decking Specifications

Preservative Treated Timber

Timber preservation means treating wood in order to maximize or extend its service life. This is done by inserting into the wood microstructure, preservative chemicals that work against wood-destroying organisms and other threats such as weathering and fire.

Preservative treated timber Hazard classes and what they mean

  • H2 – Low hazard: Dry interior and above ground
  • H3 – Moderate Hazard: Exterior above ground
  • H4 – High Hazard: Exterior in ground
  • H5 – High Hazard: Exterior in contact with heavy wet soil or in freshwater
  • H6 – High Hazard: Prolonged immersion/contact in seawater

How effective such biological preservation treatment is, will depend on several factors, including, but not limited to:

  • Which biological hazards the wood will be subjected to in-service;
  • How toxic the preservative chemicals are to the particular wood-destroying organisms the wood will be exposed to;
  • The endurance of the preservative chemicals that will remain under specific hazardous conditions after the wood has been treated (e.g. indoors versus outdoors versus submerged);
  • How well the preservative chemicals can penetrate the cross-section of the timber, and the level of retention in the penetrated zone per cubic meter of the wood, and
  • The preservative distribution gradient.

Wood Preservatives

Wood preservatives are categorized into three main categories, namely:

  • Water-borne (CCA, CuAz, ACQ, and Borate)
  • Oil-borne (Creosote)
  • Light Organic Solvent-borne (TBTN-P and Azole Permethrin)

Numerous treatment methods can be used, all with their own benefits and drawbacks. High-pressure processes (Bethell, Rueping and Lowry processes), low-pressure process, hot and cold open bath (Creosote), vacuum impregnation (double vacuum) process, and dip or pressure diffusion process.

Because different timbers have such wide-ranging absorption characteristics, it is important to use the correct methods when applying preservatives. It is good to know that the industry is required to maintain specific levels of treatment quality, as laid out in the National Standards available from the South African Bureau of Standards (SABS).

Preserving your wooden deck

There are various timber preservatives available. Some are not suitable for timber in ground contact, while others protect timber in all possible applications. Creosote and CCA preservatives are equally suitable for the support poles and bearers, and CCA treated timber is suitable for the boards. CCA treated timber has a greenish color and Creosote colors the timber dark brown or black.

Timber treated with Boron or LOSP preservatives does not change its natural appearance. The latter two preservatives are, however, leachable and should, therefore be finished with a suitable water repellent surface coating/sealer in order to be used in H3 applications. This water repellency property has to be maintained to prevent leaching of the preservatives.

A water repellent also protects the timber from degradation from weathering. In order to inhibit the effects of UV (Ultra Violet) rays at the same time, an inhibitor may be added in the form of a brown or red colorant. Remember, the use of treated timber ensures that a deck is protected against attacks from termites, borers and fungal decay. Boron, LOSP, and CCA treated timber can be painted directly once the water or solvent carrier has dried sufficiently.

Creosote timber can also be painted, provided it is first coated with a bituminous-based aluminum coating. As a general rule, preservative-treated timber in its natural form is the easiest and cheapest solution. Remember that support poles should never be cut. Order them in the lengths that are required for your deck. Only beams, boards and bearers can be cut if necessary. However, their ends should be brushed with a preservative before assembly.


It is essential that all ground contact poles are treated in accordance with at least the SANS H4 Hazard Class. Beams, bearers, and boards can be treated to H3 requirements. When choosing boards it may be possible in some areas to obtain boards with grooves on the underside. These grooves arrest curvature (cupping) to a degree, ensuring that the boards remain flat. Remember to round off the arrases of boards and be sure to install them so that the timber’s growth rings will be situated in a concave position. This will avoid splintering and surface degradation.

Treatment for your wood


It is interesting to know that, while all hardwood timbers (e.g. Eucalyptus) used in structures in South Africa must be preservative treated. Outdoor decking boards are the only one that is exempt from this requirement. This exemption is applicable to most sawn hardwood products that contain very little or any sapwood which is susceptible to insect attack an easily permeable/treatable.

While UV radiation found in sunlight can’t penetrate timbers to any depth, and the silver-grey discoloration is mainly a surface effect, that degrading effect can certainly be compounded in the presence of moisture. Over time, as a result of ongoing swelling and shrinkage as timber cell walls absorb and release moisture, the bonds between wood fibers can weaken, resulting in small cracks or checks. If the constant swelling and shrinking are not kept in check, the cracks can become significantly larger and make the timber unattractive – and potentially even structurally unsound.

Hardwood treatments

On top of that, a fixed presence of moisture can promote decay. Consider also that the inherent durability of hardwoods used for decking varies from moderate to high, depending not only on the species but also the quality of the timber selected. The presence or absence of sapwood is another factor that plays a role in the effectiveness of biological preservation systems. Many industry professionals, including suppliers and those who specialize in timber restoration, would recommend that, before installation, all the timber planks that go into building the decks be coated at least once on six sides: top, bottom, left, right, top edge and bottom edge.

This is to ensure that all the edges that are hidden from view (and sunlight) will at very least have received one coat of oil-based surface treatment. This recommendation stands, even in the case where a hardwood deck is intentionally left to age without any post-installation treatment or maintenance. In other words, it is advisable that its components be treated on all six sides at least once with an oil-based treatment before installation.


All softwood pine used for decking must be treated by the primary industrial pressure impregnation method with a suitable wood preservative. CCA is the most commonly available and widely used preservative for this purpose. CCA stands for Chromated Copper Arsenate and has been used to pressure treat timber since the 1930s, helping to protect it against wood-destroying insect attacks, decay, fungi or rot.

CCA-treated pine is a more affordable option for decking than most hardwoods, and it is a durable material for this purpose. Correctly treated H3 (Hazard Class 3) CCA-treated softwood decking is a very popular product that can be used in most areas, including coastal areas. It does very well in very dry areas in conjunction with certain oil-based surface treatments (wood sealers) used specifically for decking. H3 treated softwood decking that is treated regularly with oil-based products has a life expectancy of 50 years against fungal and insect attacks.

Post-installation treatment options for a wooden deck – paints, sealers, and varnishes

The extent to which a deck needs to be maintained depends largely on the materials used during the building process. It also depends on what the client wants to achieve with the deck. Regardless, once installed, it is important that adequate care is taken of the deck to keep it structurally sound and looking good. An important part of deck care is to keep the deck dry as far as possible, and because it is alive, it needs to be nourished. There are a number of plusses to various types of timber surface protecting treatments after installation.

While the aforementioned primary preservatives can protect wood against insects and/or fungus attacks, the level of protection against weathering will again vary. Timber can be exposed to the elements during construction and over its outdoor lifespan, putting it at risk for shrinkage, checking, splitting and cupping. Again, care needs to be taken with the application of treatments.

Oil Treatments

Heavy oily treatments can give high protection, but they are not suitable for decorative uses. On the other hand, the advantage of oil-based surface treatment is that the deck needn’t be sanded down; it only needs to be cleaned, e.g. pressure sprayed, left to dry and sealed again. If you are using a varnish, the deck will be needed to be sanded down to the wood surface, which comes with its own challenges, including hard work, as well as potentially ending up with varying thicknesses of deck planks. CCA treated pine, with pre-and post-installation oil-based treatment, does well in dry areas.

Hardwoods are not always ideally suited for decking in hot and dry areas like the Northern Cape and the Free State if it is installed without any post-installation maintenance because any oil-based timber treatment intended to protect it from the sun’s UV rays is not easily absorbed. Very specific oil-based treatments can be used to treat hardwoods and these are thinned down so as to penetrate the wood.

Preservative Treatments

Water-borne or LOSP preservative treatments (which provide limited protection during construction) are suitable for decorative uses, but they require some additional surface protection for the long term, achieved by regularly applying a good quality paint, sealer or varnish to the exposed surfaces of the wood. Whichever product is used, it must be applied according to the manufacturer’s instructions. All wood preserving chemicals must, by law, be registered by the National Department of Agriculture, which lays down conditions on their sale and use.

Note: You should not use just any oil to treat a deck. In the good old days, people used to mix diesel with raw linseed oil and used that as a deck treating option. Today, it is advised to use one of the many vetted products on the market that are refined and well-suited for decking treatment. It is also not advisable to varnish a deck, but rather to treat it with an oil-based decking treatment.

DIY Treatment Recipe

This natural wood treatment is a protective coating that can be applied to wood surfaces to enhance durability and longevity. It is formulated using raw linseed oil, gum turpentine, pine tar, and optional driers. Additional natural earth pigments like Burnt Umber or Venetian Red can be added for color customization. The treatment offers various benefits such as water resistance, protection against pests, anti-fungal properties, and microbial resistance. It allows the wood to breathe while sealing and safeguarding it from water damage.

Instructions for Application:

  1. Mix the ingredients in the following proportions:
    • 1 part raw linseed oil
    • 1 part natural gum turpentine (not petrochemical substitutes)
    • 1 part pine tar
    • Optional: Add driers as per the manufacturer’s instructions based on the quantity of linseed oil used. This accelerates the drying process.
    • Optional: For color customization, add 50-100 grams of natural earth pigment per liter (e.g., 50 grams Venetian Red or Red Iron Oxide, and 100 grams of Burnt Umber for a redwood brown color).
  2. Gently heat the oil on an electric cooker and add the pine tar. Mix until blended. Note that pine tar may be solid or liquid, depending on its production process.
  3. Once the mix reaches approximately 80 degrees Celsius, remove it from heat and wait for 10 minutes.
  4. Add the gum turpentine, driers (if using), and pigments (if using). Stir well.
  5. Apply the treatment warm for better penetration and coverage.
  6. The drying process depends on air circulation, so choose a windy, dry day to speed up drying.
  7. The recommended application is 2 coats. The first coat can be thinned with more gum turpentine, and the second coat can be applied 24 hours later without thinning.
  8. For a glossier finish, reduce the amount of gum turpentine in the mixture.
  9. Expect a light tar smell initially, which will fade over time.


  • Protection against pests and fungi.
  • Long-lasting and superior to commercial treatments.
  • Allows wood to breathe while repelling water.
  • Provides a gentle golden brown color to untreated wood.
  • Additional UV protection for lighter treatments by adding Vitamin E Oil (50-100 grams per liter).


  • Refresh the treatment every 10 years or as dictated by climate conditions.

Note: Use digital scales for precise pigment measurements, as excess pigments cannot be undone once added.

About this Recipe…

This recipe is based upon the age-old timber preservation traditions of the Scandinavian Countries and is centuries old and time-proven. It is used on the Oldest Log Cabin in the world, which is located in the Faroe Islands, and that is over 900 years old and in one of the harshest environments in the world. It is also traditionally used on wooden boats and other timber which is exposed to the elements. We have various other variations of this treatment using blends of other natural oils to obtain different finishes, but the one above is a fit for all treatments and beats hands down any other commercially available treatment sold by the big chemical companies which do not last and require regular re-treatments.

This treatment is especially suited to wet climate conditions but can be used in all climatic conditions. The best thing about this treatment is that it is 100% natural ingredients, except for the driers, but this is a tiny percentage of the overall ingredients, and the driers are only added to speed up the drying time. So if you want a totally natural ingredient finish and do not mind waiting longer for it to dry than usual, then leave out the driers.
This recipe is taken from Misha Dutton – Scotland.

Do’s and Dont’s

  • If your wooden deck bounces when you walk over it, do not accept it! Your tea should remain inside of your cup and not spill out into the saucer or onto your deck.
  • If you are using Balustrade posts, then they should be bolted to the sub-structure and not nailed (they will come lose eventually).
  • The balustrade should not have any gaps where a 100mm ball in diameter could fit through.
  • When building a wooden deck, any part of the structure that is 1m or higher off the ground requires a balustrade.
  •  When building a deck, the timber structures should have at least a space of 450mm below the decking for air to flow around the timber. If it is not possible, try to keep the timber above the soil.

a Wooden deck is an attractive addition to any structure and standalone (like on a beach or a boardwalk). It makes for a durable and functional statement piece. Timber decking, however, like all other constructions, should be approached as an investment. You as the homeowner or project manager will do well to investigate the subject, ask for advice, engage in the services of an accredited professional from design to final inspection, and ensure that the proper and regular maintenance is conducted.

The conclusion to our crash course

The time and effort that should go into the planning and maintenance of a wooden deck can not be compared. From the pleasure that comes with contemplating one’s natural surroundings or spending time with your friends and family on a beautiful structure. Made from a natural, potentially carbon-negative material, if constructed and taken care of correctly, a deck is for a living – and for life.

Bonus: Decking floors you never even knew existed

Over the years, timber decking continues to be a popular choice that increases daily for many decking applications. But did you know that most of the decking boards can be very slippery in wet conditions? These slippery floors can, and will result in accidental slips, falls and personal injury. Luckily for you, here at Sabie Poles, we offer the highest quality non-slip decking floors for better control. We will provide you with a hazardous free decking solution. No need to search far and wide for non-slip decking, no matter how near or far you are, we deliver! So make the right choice, call us now for your non-slip decking boards.

Non-slip decking is a lifestyle

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