When purchasing timber for DIY projects, a knowledge of materials, particularly timber and laminates, and of how best to use tools is essential to good craftsmanship, even if your ambitions extend no further than making and hanging a simple shelf.
Timber is among the most versatile of materials and has an almost endless rang of applications in all forms of construction. Timber can be bought either sawn or planed.
- Planed timber is sold planed all round (PAR), or planed both sides (PBS). Planing reduces the timber to a “nominal” size. A piece of timber 1 in. (2.5 cm) in size is reduced, when planed, to 2.2 cm; a board measuring about 6 in. (or 15 cm) reduces to about 14.5 cm.
- Unedged boards (UE) retain the shape of the tree at the edges.
- Sawn-edged boards (SE) have unplaned edges.
- It is cheaper to buy timber in standard sizes. If you buy less than a standard size,’ you may be charged up to the next size. If you buy odd sizes, you will be charged more for cutting.
Right wood for the job
- It is important to use the light wood for the particular job. There are two basic timber types — natural and man-made. Categories of natural timber are hardwood and softwood. The most common types of manmade timbers are chipboard, blockboard, hardboard and plywood.
- Outdoor timber should be able to withstand all kinds of weather and, therefore, be durable and as rot-resistant as possible.. Timbers in this category include sweet chestnut, oak, teak and western red cedar.
- For uses such as garden furniture, teak and oak, though expensive, are best. Sweet chestnut is cheaper and lighter but not always easily obtainable. Western red cedar is light, durable, soft and reasonably cheap.
- Softwood can be used out of doors but should be coated with a preservative or be well painted. It can be used as a framework of a shed or for doors. Deal should be knot-free. Western red cedar, Douglas fir, hemlock and parana pine are other softwoods. These are normally free from knots in most sizes but more expensive than deal. Hardwoods, such as beech and ramin, are generally used where two timber surfaces are in moving contact — such as folding chairs and the rails for drawers.
- Birch is a whitish-to-light board. It is easy to work and turns, stains, polishes and glues well. Uses are general joinery, moulding and furniture.
- Elm, yellowish-brown in colour, is variable to work but takes a good finish. It nails, screws, stains and polishes well but needs careful selection and seasoning. Uses are general joinery and furniture.
- European whitewood, white to pale-straw in colour, nails, screws and glues well. Uses are general joinery and carpentry. Douglas fir, light-reddish brown, is reasonably easy to work but requires care in nailing and screwing. It glues well. Its uses include all types of joinery and constructional work.
- Mahogany is easy to work and nails, screws and glues well. It varnishes and polishes well, but care is needed when staining it.
- Oak, moderately easy to work, needs care when nailing and screwing. It stains, polishes, varnishes and glues well. Avoid its contact with metal in damp conditions, as corrosion can occur.
- Parana pine is creamy-brown in colour and easy to use. I.t often has highly attractive graining and finishes excellently. It is valuable for interior use, including worktops and general carpentry.
- Red Meranti and Red Seraya are pink to reddish brown and easy to work. They nail, screw, glue, finish, polish and stain well. Teak has a greasy feel but works reasonably well. Some care is needed when nailing and screwing. It varnishes and polishes well. Uses include draining boards and garden furniture.
- Western Hemlock is a pale-brown softwood which is moderately easy to saw. With fair nailing, screwing and finishing properties.
- Western red cedar wood, which is easy to use satisfactorily. It is liable to damp conditions. Uses – joinery, weather-boards.
Chipboard is the most widely used manmade board. It is made from chips of timber and is available both veneered and pre-finished. It can be cut easily and planed at ends but does not, in general, lend itself to being worked in the same way as natural timber. On the other hand, it is less liable than natural timber to expansion and contraction from the effects of humidity. There are four main grades:
- Standard the cheapest;
- Painting, which is suitable for decoration;
- Flooring, the strongest;
- Exterior grade, which is treated to resist water.
Pre-finished boards may be either timber or plastic-laminated, with edging strips to match the surface.
Plywoods are veneers — thin sheets of timber glued together under pressure, with grains at right angles on adjacent sheets. Plywood generally has an odd number of sheets to inhibit warping. It ranges from two-ply up to 11-ply and is made in both soft and hardwood. Ordinary ply does not resist weather, but there is a weatherproof grade called WBP (short for water and boil-proof). Ply is also made with decorative hardwood veneer on one side and is available plastic-laminated.
Fibre building boards are basically insulating board and hardboard. Standard hardboard has one smooth and one rippled surface. Double-faced hardboard is available for use where both sides will show. Blockboard is made of thin timber outer veneers with a core of solid wood. It is stronger than chipboard and can be used for heavy-duty purposes, such as shelving. It is stable and unlikely to warp.
Man-made boards can be cut with a panel saw or a tenon saw, but excess pressure should be avoided when cutting hardboard, as this tears easily. Always cut manmade boards from the face side and finish edges with a smoothing plane.
When buying timber, add a little extra to allow for dirty or damaged ends — roughly ¼ in. (1.2 cm) for every 2 ft (or 61 cm). Material with large knots bends and twists, should be rejected, for this will be weak.
Waney-edged timber has bark at the edges which reduces its effective width. End splits, or “shakes-, may extend a long way up a board — and are faults to look for. Compression shakes, splitting across the board; cupping, a warped curve across the width of a board: bowing, bending along the entire grain; and springing, a board bent edgeways, are other main faults.