An obvious tendency from recent research in the area of composite slabs is to substitute design rules based on so called parametric tests and m-k method by design rules that are established on structural principles. The aim of this paper is to show advantages of partial connection strength method based on three interface characteristics evaluated from the small scale tests: mechanical interlocking resistance, friction at the support, and reduction of the mechanical interlocking due to high strains in the profiled sheeting. The design method, so called 3P PCSM, is proposed for a possible inclusion as an alternative method for design of composite slabs with shallow profiled sheeting in Eurocode 4. The proposal is an improved version of the existing partial connection strength method because it uses a similar structural model to calculate design bending resistance but it covers even a slab with brittle behaviour. A design example is given to illustrate the proposed procedure and to compare results obtained by various design methods