Today, most DIY stores and timber merchants can offer large flat boards to suit every need. Manmade boards can be divided into fibreboards, particle boards and laminates. Generally, boards are cheaper than solid wood, and more stable when exposed to heat and moisture changes. However, wood is still ideal for battens and posts because of its strength along the grain. It also has a unique warm appearance for furniture projects.
Timber yards sell standard lengths of wood (ie 1.8, 2.4, 2.7, up to 4.8m for sawn timber) and it is more economic to buy full lengths, in as long a length as possible. Plan any large joinery project around these sizes.
Wood is commonly sold in nominal sizes - as it started off before planing. The finished size can be as much as 6mm under this, so take a tape measure to the store to check exact sizes if necessary. Ask for kiln dried (marked KD) timber for furniture projects to reduce the problem of timber movement.
Most timber yards will let you choose the lengths you want from stock. Look out for:
End cracks - these will have to be sawn back to clean timber.
Cupped or twisted wood. Look down the length of the wood, checking each surface, to spot badly warped wood and reject it.
Dead knots are dark brown or black and will become detached from the timber.
Surface staining, stick marks and insect holes should be avoided for timber that will be seen.
It's usually cheapest to buy full size boards (2440 x 1220mm) but larger DIY stores sell 1220 x 610mm and 900 x 600mm sheets for convenience. Standard thicknesses are 4, 6, 9, 12, 15, 18 and 22mm - you can order 3, 25 and even 35mm sheets of some boards. Chipboard for countertops can be up to 50mm. Specialist timber merchants can supply extra large 3050 x 1525mm boards and special finishes.
Do not buy wavy or bent boards as they are difficult to straighten.
When you get the boards home, try to store them upright, preferably clear of the floor. Make sure they lean towards a wall and cannot be accidentally pulled over. Support thin boards with a thicker board at the back so that they don't warp.