Verified Timber Grades

Verified Timber can be produced by two types of grading system, machine stress grading and visual grading. Timber graded under both systems is tested in the same way through random sampling and testing on a properly calibrated bending test machine. Rigid pass requirements must be adhered to by all Verified Timber licensees to ensure that standards of strength and stiffness are maintained.

Table 1 - Minimum target values for visually graded timber
Species Grade

Bending strength
fb

(MPa)

Compression strength
fc

(MPa)

Tension strength
ft

(MPa)

Modulus of elasticity
E

(GPa)

Fifth percentile modulus of elasticity

(GPa)

Moisture condition - Dry (m/c = 16%)
Radiata Pine & Douglas Fir VSG10 20.0 20.0 8.0 10.0 6.7
VSG 8 14.0 18.0 6.0 8.0 5.4
Moisture condition - Green (m/c = 25%)
Radiata Pine & Douglas Fir G8* 11.7 12.0 4.0 6.5 4.4
*G8 is a visual grade which has been verified in the green condition for when the timber will be used in a service situation where the moisture condition may be 25% or over.
Table 2 - Minimum target values for machine stress graded timber
Species Grade

Bending strength
fb

(MPa)

Compression strength
fc

(MPa)

Tension strength
ft

(MPa)

Modulus of elasticity
E

(GPa)

Fifth percentile modulus of elasticity

(GPa)

Moisture Condition - Dry (m/c = 16%)
Radiata Pine & Douglas Fir MGS15 41.0 35.0 23.0 15.2 11.5
MGS12 28.0 25.0 14.0 12.0 9.0
MSG10 20.0 20.0 8.0 10.0 7.5
MSG 8 14.0 18.0 6.0 8.0 5.4
MSG 6 10.0 15.0 4.0 6.0 4.0

Note: A producer can offer other species or grades with different stresses and moduli subject to verification in accordance with the standard NZS3622:2004.