This part of ISO 834 specifies the procedures to be followed for determining the fire resistance of loadbearing horizontal separating elements when exposed to heating from the underside. The test is also appropriate for the evaluation of loadbearing separating elements containing beams when it is not possible to test the floor or roof assembly in a representative manner without them. However, the data cannot be transferred directly one to the other. The application of this test to other untested forms of construction is acceptable when the construction complies with the direct field of application as given in this part of ISO 834 or when subjected to an extended application analysis in accordance with ISO/TR 12470. Since ISO/TR 12470 gives only general guidelines, specific extended application analyses are to be performed only by persons expert in fire-resistant constructions.