Core drilling is a semi-destructive method where cores of small diameter of about 5 mm are extracted from members and tested in a compression device. Small core tests are correlated with the standard small-clear specimen tests to evaluate compressive strength and modulus of elasticity. Cores are smaller than natural defects such as knots and can be plugged after testing. This is a local method that gives localized information about the mechanical properties of the clear wood. The method requires special testing fixture and testing equipment.