Investigations of radon and thoron emanation from wall materials have been performed by means of a method based on radon ²²²Rn and thoron ²²⁰Rn concentration determination in an emanation chamber. Surface and mass coefficients of radon emanation and surface coefficient of thoron emanation have been determined. Dependence of the coefficients on the kind of wall materials, coverage of the wall and the outer surface finishing has been investigated. Measurements in situ have been also performed in selected rooms.