Hardness is an important feature of wood species. One type of wood is harder than the other. The harder the wood, the more durable the floor. The hardness of the wood is measured in Janka, also known as the "Janka Hardness" system (N). This means the force in kg required to push a smooth steel ball with a diameter of 11,824 mm to the middle of the wood (the surface of the half steel ball is exactly 100 mm²).


The hardness generally increases very strongly with the bulk density. At the front end, the hardness is greater than on the other surfaces. The abrasion resistance is important for wood floors and mechanical, moving parts. The abrasion resistance of wood types is considerably larger at the end grain than at the longitudinal plane, and also shows a relatively large similarity with the hardness.


The influence of brushes on the strength of wood depends on the size of the brushes in relation to the dimensions of the wood, preventing it from appearing close together  and the place in the wooden element. Strong properties are greatly influenced by the wire run. For example, the tensile strength of a piece of wood with twisted wire will be significantly lower. That tearing (for example by carelessly drying) and biological damage such as insect ducts and wood rot by fungi can dramatically reduce the wood's strength properties, speaks for itself.


The table below shows types of wood and their hardness according to Janka. The higher the Janka number, the harder the wood.

Wood Species Hardness according to Janka (N)
Pinus Ponderosa 2000
French Pine 2670
Pitch Pine 3600
Siberian Larch 4000
American Cherry Wood 4630
Cherry Maple 4680
Curupixa 5250
Beechwood 5470
Sipo Mahogany 5600
American Oak 6050
American Ash Wood 4160
French Oak 6280
Brown Maple 6440
Hard Maple 6440
Merbau 6590
Padouk 6860
Afzelia Pachyloba 8200
Sucipera Preta 8750
Jatoba 10400
Myiracatiara 15600
Ipe (Greenheart) 16700