Timber, Boards & Woodworking Materials Guides

What Timber, Boards & Woodworking Materials covers

This section covers wood and wood-based materials: structural and general timber, plywood and sheet boards, and the species and grades sold through South African merchants.

The first thing worth establishing is that “wood” at a merchant is several quite different products. Solid timber is sawn from a log and behaves like the tree it came from — it moves with moisture, has grain direction, and varies in strength along it. Sheet boards are manufactured: plywood is thin veneers glued in alternating directions, which is why it is stable and strong in both directions; chipboard and MDF are particles or fibres bonded with resin, which makes them flat, consistent and cheap, and also much weaker and far less tolerant of water.

The second is that timber for structure is not the same as timber for appearance. Structural timber is graded for strength and, in South Africa, is treated and marked accordingly. Using ungraded or untreated timber in a roof or load-bearing position is not a saving; it is a code and safety problem.

South Africa’s common species are largely pine, with blue gum and other hardwoods for specific uses. Treatment class matters as much as species, because it determines where a piece may be used, and a treated piece used outside its class fails early regardless of how good the timber was.

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How the guides in this section differ

Solid timber or manufactured board. Different strengths, different tolerance of moisture, different fixings.

Structural or non-structural. Structural timber is graded and marked. Anything carrying load — roof trusses, beams, joists — needs the correct grade and treatment, and generally an engineer’s involvement.

Treated or untreated. Treatment classes cover indoor dry use through to ground contact. Untreated pine outdoors in South African conditions has a short life, and borer and termite damage is a real consideration.

Interior or exterior board. Ordinary plywood and MDF are not exterior products. Exterior-grade plywood uses different adhesive; marine ply is different again. MDF swells irreversibly when wet.

Material	Made from	Good for	Avoid
Structural timber	Graded sawn softwood	Roofs, framing, load-bearing	Ungraded stock for structure
General timber	Sawn softwood	Shelving, framing, non-structural	Outdoor use if untreated
Plywood	Cross-laminated veneers	Strong panels, some exterior grades	Using interior grade outdoors
Chipboard	Bonded particles	Cheap flat panels, carcassing	Anything damp or load-bearing
MDF	Bonded fibres	Painted furniture, mouldings	Moisture; screwing into edges
Hardwood	Dense species	Furniture, flooring, exposed work	Assuming softwood fixings suit it

Safety, accuracy and next-step checks

These guides explain what materials are for. Anything structural needs a qualified professional and, in most cases, municipal approval under the National Building Regulations.

Points worth carrying:

MDF and chipboard dust is a respiratory hazard. Cutting and sanding releases fine dust containing bonding resins. Cut outdoors or with extraction, and wear a properly rated mask rather than a nuisance dust mask.
Never use ungraded timber structurally. Roof and load-bearing members must be correctly graded and treated. This is a safety and compliance requirement, not a preference.
Match treatment to exposure. Ground contact, exterior above ground and interior dry are different treatment classes. Using the wrong one shortens life dramatically.
Cut ends need re-treating. Cutting through treated timber exposes untreated core; apply an end-seal preservative.
Timber moves. It expands and contracts with humidity. Allow for movement in flooring, cladding and wide panels rather than fixing rigidly.
Store it flat and dry before use. Timber stored badly on site warps and is then blamed on the supplier.
Wear eye and hearing protection when machining, and mind kickback with circular saws and routers.
Check for termites and borer, which are a real problem in parts of South Africa. Treated timber and correct detailing matter.

Frequently asked questions

What is the difference between plywood and chipboard? Plywood is thin veneers glued in alternating grain directions, making it strong and relatively stable. Chipboard is bonded particles: flatter and cheaper, but much weaker and poor with moisture.

Can I use MDF in a bathroom? Standard MDF should not be used where it may get wet — it swells and does not recover. Moisture-resistant grades exist but still are not a substitute for a genuinely waterproof material.

Does timber need treating? For outdoor use, ground contact or anywhere at risk of insects and damp, yes, at the correct treatment class. Interior dry applications may not need it.

Which timber for a roof? Correctly graded and treated structural timber, sized by an engineer or supplied as designed trusses. This is not a DIY specification decision.

Why did my timber warp? Usually moisture change — stored damp then dried, or fixed rigidly with no allowance for movement. Storing flat, dry and supported before use prevents most of it.

Timber, Boards & Woodworking Materials Used-For Guides