This presentation discusses the air permeability of building board materials used in the airtight layer of timber structures. The laboratory test was performed of different samples: plasterboard, oriented strand board, cross laminated timber and surface coating participle board. The methodology of this laboratory test is described in the standard STN EN 12114. The significance of this work consists in determining values of air permeability of different building board materials. The plasterboard and cross laminated timber samples met requirement of air permeability q50< 0.1 m3/ (m2.h).