Green oak structural grading

We also offer structural Oak visually graded to TH2/ D24, THB/ D30 and THA/ D40.

The strength of a piece of wood depends on its species and is affected by growth characteristics such as knots, wane, slope of grain, and splits ect.  Visual grading rules specify the size, type and number of defects allowed for each grade.

Visual grading is a slower process than machine grading. The visual grader, however, can be more flexible and is invaluable where a relatively small parcel of timber needs grading.  In event of a dispute, a visual grader may be able to confirm the strength grade of timber already used and in-situ.

For our declaration of conformity please click here:

What do I need

Structural grading in oak is broken down in to two sizes with two qualities in each.

Sections with a cross section above 20000mm2 (32" sq inches) (for example larger than 8"x4") can be graded THA or THB. THA is the top structural grade and is rated D40. THB is the standard grade we get asked for most and is structurally rated at D30.

Sections with a cross section below 20000mm2, but above 2000mm are graded either TH1 or TH2. TH1 is the top structural grade and is rated D30. TH2 is the standard grade we get asked for most and is structurally rated at D24.

The summary of limitations is linked to the relevant grade above.