Large buildings can not always be tested as a single pressure zone. In Europe, different approaches have been proposed concerning the choice of representative parts of the building (sampling method) and the compliance check in situations, when several parts of the building have to be tested separately. The preliminary Czech standard TNI 73 0330 defines a sampling method, as well as subsequent treatment of results and compliance check procedures for multifamily residential buildings. This contribution reports the results of a trial test of TNI 73 0330 method. The estimation of the whole building n50 value by means of this sampling method was found questionable, namely due to the potential presence of internal air leakage. Alternative method based on measurements of building parts using so called guard zone technique was proposed. Inconsistency between the compliance check based on the whole building test results and the sampling method test results was identified.