Timber comes in standard lengths of 0.9-6m in increments of 300mm. Width and thickness ranges from 10-200mm. Other dimensions have to be specially ordered.

Timber comes in the following grades:

Select (No. 1 clears): Has straight grain, is free of knots and is suitable for high-quality cabinetwork.

Select merchantable: Has straight grain but some knots and is used fordoor and window joinery.

Merchantable: Has wavy grain and larger knots and is used for frame construction.

Standard or building: Has sloping grain and larger knots and is used for battens and bracings.

Engineering: Is free of defects and has straight, tight grain for high-quality structural timber.

Stress grading refers to the amount the timber will bend and is shown by an 'F' number - the higher the number, the greater the strength.

How to order timber

To leave an order with a timber merchant you need to know:
1. The width and thickness of each part, eg 100mm x 50mm
2. The length, eg 1.2m
3. The condition:

• Sawn or rough sawn: sawn to a specific (nominal) size
• Dressed: DAR (dressed all round) D2S (dressed on two sides) or DD (double dressed)
• Milled: dressed toa specific profile for architraves, window sills, skirting boards and so on.

4. The species, eg Radiata pine (as pictured above)
5. The number of pieces

6. The stress grade (in construction work)

Source: Basic Carpentry Techniques (Murdoch Books)