Strength group

Group representing the inherent strength of a timber species—unseasoned timber (S1 to S7) and seasoned timber (SD1 to SD8).

Group representing the inherent strength of a timber species:

  • There are seven strength groups for unseasoned timber: S1 (strongest) to S7 (weakest) and eight for seasoned / dry timber: SD1 to SD8).
  • Seasoned and unseasoned timber have different strength groupings due to differences in the mechanical properties of defect-free timber of a given species in each condition.
  • Classifications without brackets (i.e. S and SD) were determined from mechanical test data using small, clear specimens.
  • Classifications in brackets e.g. (S2) and (SD3) are provisional assessments based on density and/or limited mechanical test data.
  • Provisional classifications can be used with confidence as they are assessed conservatively. The strength groups agree with AS/NZS 2878-2000 Timber—classification into strength groups (Standards Australia 2000a).

See the guide: Strength groups & stress grades.

There are currently no values set for this field group.