Comparison of Various Standards for the Characteristic Strength and Stiffness of Timber

Comparing published design stresses for radiata pine with those for both visual and machine grades from AustraliaUSA, UK and ISO, in the nominal 150x50 mm dimension, it was found that:

• Radiata pine has a relatively high assigned strength compared to other visual grades.

• For US visual grades radiata pine No. 1 Framing is closest to the Ponderosa #1 grade, Redwood #2 grade and Douglas fir – south #1 grade.

• For US machine stress rated (MSR) timbers, No. 1 Framing radiata equates closest to 1200/1.2 grade while Engineering grade radiata equates closest to 1950/1.5 grade.

• The MGP system tracks very closely with the ISO system for softwoods, with MGP8 grade equating to the ISOS14 grade.

• The Australian F-grade system clearly does not suit softwoods.

• No. 1 Framing radiata is closest to C16 grade in the EN 338 (Eurocode) system.