Foam concrete (FC) is little used material in construction practice and it has very good potential for utilization in the civil engineering and building construction. Nowadays, it is primarily used as a leveling layer in the floor of the buildings, but its utilizability is much wider because of its particular properties. Its main characteristics are its material property and that it consists of void pores. This allows to achieve the low bulk density and saving of material inputs. As a building material, it has adequate mechanical characteristics and low thermal conductivity. A series of dynamic testing using light weight deflectometer (LWD) was carried out to estimate the reliable value of the dynamic deformation modulus that can represent the quality of the sub-base made from foam concrete beside the bulk density investigation. Static strain moduli from the second load cycle is the common required value for the sub-base design. Due to larger stiffness and thus larger deflection radius, conventional PLT apparatus is not suitable for foam concrete testing. On the other hand, when adequate dynamic modulus based on the conventional strain modulus is determined, LWD testing is quick method for the foam concrete testing. This paper presents the first attempts to estimate this relation.