South African Pine is just as strong but myth has us all believe that imported timber from our northern neighbors is stronger than our Pine. Pine is a highly anisotropic material with high strength and stiffness parallel to the grain but low properties perpendicular to the grain. These factors must be taken into account in the design of timber structures.
(An interesting fact is that Australian Buloke – An ironwood tree that is native to Australia, (a species of tree occurring across most of Eastern and Southern Australia) is known as the hardest wood in the world, this particular type has a Janka hardness of 5,060 lbs.)
To refer to the strength of timber we have to take 3 factors into consideration. Physical properties of wood that contribute to the strength are;
The density of wood is determined mainly by the amount of wood substance per unit volume and the moisture content.
|South African Softwoods|
|Common Name||Country of Origin||Density|
(kg / m3)
|Pinus Elliottii||Elliottii Pine||South Africa||494|
|Pinus Patula||Patula Pine||South Africa||498|
|Pinus Radiata||Radiata Pine||South Africa||611|
|Pinus Taeda||Taeda Pine||South Africa||578|
Shrinking and swelling
Below the fiber saturation point, wood shrinks and swells as its moisture content falls and rises. The rate of shrinkage/swelling varies with direction. Values in the parallel to grain direction are 5 to 10% of those in the perpendicular to grain direction while values in the tangential direction can be 1 to 2 times those in the radial direction.
Timber has low thermal conductivities and coefficients of thermal expansion. The tensile strength of softwoods parallel to grain at 12% moisture content generally ranges between 70 to 140MPa. The compression strength is lower and is usually in the range of 30 to 60 MPa. For hardwoods, these values are generally higher. These values are for clear, straight-grained wood samples. It remains an important construction material today as research and improved technology have led to a better knowledge of the material behavior. This has helped designers to use timber more efficiently and safely and in more challenging and exciting applications.
Keep in mind that every few years changes in the environment and seedlings calls for changes in the grading process. Grading/testing and classifications are never stopped in the sawmilling industry.
11 Attributes of timber
- It has a warm texture
- attractive appearance
- Can be used external and internal
- Can be use for the main structures of buildings
- Easy to work with
- Can be produced in a wide range of shapes and sizes
- It has a high strength-to-weight ratio
- has good thermal insulation properties.
- Timber can be used compositely with concrete and steel.
- It is the only construction material that does not contribute to greenhouse emissions and is a fully renewable product
- Recyclable material.
Grading timber for strenght
Let’s touch on our grading of timber in the sawmilling industry. Thicker and broader boards are not necessarily stronger! To minimize the risk of substandard structural timber entering the market, the South African sawmilling industry, through Sawmilling SA, decided to develop two quality control standards for structural timber graders (SANS 1783-5-1 and SANS 1783-5-2). The standards are a product of cooperation between several people and organizations. It requires continuous sampling and destructive testing of graded South African Pine timber to ensure that the measured grading properties are good predictors of strength and stiffness.
Human operators perform visual grading for characteristics such as knots and density, or machines equipped with various sensors or mechanical devices grade the timber. Large-scale testing associates the non-destructively measured properties of timber with its strength and stiffness characteristics. Therefore, most grading systems depend on a consistent relationship between the measured properties and the mechanical performance of the wood.
The boards are all stamped on the ends after the mechanical test have been made. (S5 or S7 or UTP). You could purchase your CCA pressure-treated S5 construction material at Sabie Poles.
What is South African Pine S5 grade?
The S5 grade indicates that it complies with a certain stress grade, which is related to specific strengths. These commodities are also available in rough sawn sizes. The rejects from the above grades are called “Utility”, which is graded according to in-house specifications. Also known as UTP. Our S5 construction timber, Cladding, Decking and flooring is the perfect South African Pine for the job
Now that we know a little bit more about the strength of pine, let us take a peek at what type of pine species do the Northern countries grow?
Pine species of the northern countries
Aleppo pine has been extensively used as a reforestation species to restore degraded areas. Indeed, Aleppo pine is one of the few species that easily grows on poor and dry soils. In semi-desert regions, particularly in Libya, this species is distinguished by its tolerance to drought, growing in areas with 250 mm annual rainfall. However, the species cannot withstand prolonged periods of frost and is vulnerable to heavy snowfall, as its branches are fragile and easily broken. In Tunisia, Aleppo pine forests (Pinus halepensis Mill.) have fundamental environmental, economic, and social roles.
The Aleppo pine forests extend over 10,000 km2 in North Africa – 8,550 km2 in Algeria, 2,965 km2 in Tunisia, and about 650 km2 in Morocco – and constitute the southernmost Mediterranean forest type, serving as a tree-steppe belt in the ecotone between the Mediterranean forests and the grassland steppes. It takes approx. 50 years to reach maturity!
The average increase in height and diameter of this species does not exceed 7 cm year and 0.25 cm respectively. Many stands of Aleppo pine originate through reforestation.
Because these trees only grow approx. 0.25cm in diameter during a year the timber is very dense.
Depending on where timber is sourced in the northern countries, mills use different grading systems and some producers use no system at all!
Some Mediterranean species are of economic importance not only for their timber but for pine nuts that have high market value, and their production can increase the economic value and development of degraded and marginalized areas.
It is safe to conclude that South Africa has all the checks and balances in place to ensure that just the best products are used for building.
You can Trust our Construction Timber
We are proud of our grading systems at Sabie Poles. All of our timber products management systems meet the international ISO 9002 standards. We are proud to be an exporter of top-quality CCA Treated Timber products to all SADC countries and the rest of the world! We supply Construction Grade S5 South African Pine for the building and hardware industry
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