This British Standard specifies a method of strength grading temperate hardwood visually for structural use.

The permissible limits of characteristics for temperate hardwoods are specified for two visual strength grades for large size timber, designated “Heavy Structural Temperate Hardwood” (THA and THB), and two visual strength grades for smaller size timber, designated “General Structural Temperate Hardwood” (TH1 and TH2).

This British Standard applies to temperate hardwoods, graded for use in the United Kingdom.