EN 338 - Table 1 - Strength classes - Characteristic Values
Wood Class Strength Properties (in N/mm2) Stiffness properties (in kN/mm2) Density (in kg/m3) Density (in kg/m3)
Bending Tension Paralel Tension Perpendicular Compression Parallel Compression Perpendicular Shear Mean modulus of elasticity parallel 5% modulus of elasticity parallel Mean modulus of elasticity perpendicular Mean shear modulus
  fm,k ft,0,k ft,90,k fc,0,k fc,90,k fv,k E0,mean E0,05 E90,mean Gmean rk rmean
C14 14 8 0.4 16 2 3 7 4.7 0.23 0.44 290 350
C16 16 10 0.4 17 2.2 3.2 8 5.4 0.27 0.5 310 370
C18 18 11 0.4 18 2.2 3.4 9 6 0.3 0.56 320 380
C20 20 12 0.4 19 2.3 3.6 9.5 6.4 0.32 0.59 330 390
C22 22 13 0.4 20 2.4 3.8 10 6.7 0.33 0.63 340 410
C24 24 14 0.4 21 2.5 4 11 7.4 0.37 0.69 350 420
C27 27 16 0.4 22 2.6 4 11.5 7.7 0.38 0.72 370 450
C30 30 18 0.4 23 2.7 4 12 8 0.4 0.75 380 460
C35 35 21 0.4 25 2.8 4 13 8.7 0.43 0.81 400 480
C40 40 24 0.4 26 2.9 4 14 9.4 0.47 0.88 420 500
C45 45 27 0.4 27 3.1 4 15 10 0.5 0.94 440 520
C50 50 30 0.4 29 3.2 4 16 10.7 0.53 1 460 550
D18 18 11 0.6 18 7.5 3.4 9.5 8 0.63 0.59 475 570
D24 24 14 0.6 21 7.8 4 10 8.5 0.67 0.62 485 580
D30 30 18 0.6 23 8 4 11 9.2 0.73 0.69 530 640
D35 35 21 0.6 25 8.1 4 12 10.1 0.8 0.75 540 650
D40 40 24 0.6 26 8.3 4 13 10.9 0.86 0.81 550 660
D50 50 30 0.6 29 9.3 4 14 11.8 0.93 0.88 620 750
D60 60 36 0.6 32 10.5 4.5 17 14.3 1.13 1.06 700 840
D70 70 42 0.6 34 13.5 5 20 16.8 1.33 1.25 900 1080