Untersuchungen zur Wasseraufnahme von Vollholz und Holzwerkstoffen

Investigations on the water absorption of solid wood and wood-based materials.

The water absorption coefficient is an important parameter for water transport calculations in building physics. However, only few values exist for wood and wood-based materials. Therefore, the water absorption of different wood species (spruce, beech, oak, ash) and wood-based materials (solid wood panel, plywood, OSB, particle board, MDF, insulating fibreboard) was tested by partial immersion according to DIN EN ISO 15148. In general, water absorption was clearly higher parallel to the fibre and in plane direction than perpendicular to the fibre and perpendicular to the plane. Particle board and fibre board showed in contrast to the other investigated wood-based materials and to solid wood a non-linear trend of water absorption perpendicular to the plane due to their density profile. The water absorption of insulating fibreboards was highly affected by additives (latex, paraffin, starch, PUR, flame retardants, polyolefin fibres). For example, the addition of polyolefin fibres and flame retardants results in a two orders of magnitude higher water absorption coefficient compared to insulating boards without additives.