This Part of this European Prestandard specifies a test method for determining the ability of a horizontal protective membrane, when used as a fire resistant barrier, to contribute to the fire resistance of horizontal structural building members.This European Technical Specification contains the fire test which specifies the tests which are carried out whereby the horizontal protective membrane, together with the structural member to be protected, is exposed to a fire test according to the procedures defined herein. The fire exposure, to the temperature/time curve given in EN 1363-1, is applied to the side which would be exposed in practice and from below the membrane itself.The test method makes provision, through specified optional additional procedures, for the collection of data which can be used as direct input to the calculation of fire resistance according to the processes given within EN 1992-1-2, EN 1993-1-2, EN 1994-1-2 and EN 1995-1-2.A related test method for determining the contribution to the fire protection of vertical structural members by vertical protective membranes is given in Part 2 of this ENV.This European Technical Specification also contains the assessment which provides information relative to the analysis of the test data and gives guidance for the interpretation of the results of the fire test, in terms of loadbearing capacity criteria of the protected horizontal structural member.The limits of applicability of the results of the assessment arising from the fire test are defined, together with permitted direct application of the results to different structures, membranes and fittings.This European Technical Specification applies only where there is a gap and a cavity between the horizontal protective membrane and the structural building member. Otherwise the test methods in ENV 13381-3, ENV 13381-4 or ENV 13381-5, as appropriate, apply.Tests shall be carried out without additional combustible materials in the cavity.