This paper deals with the comparison of parametric and non-parametric metamodels used in design procedure of pultruded glass fibre reinforced plastic (GFRP) deck panels. Stiffened deck structure loaded under the three-point bending and uniform distributed load has been examined. A set of five hundred sample points has been evaluated by means of finite element analysis and stiffness and strength responses extracted for building of metamodels. Moreover, set of complimentary physical experiments has been carried out in order to verify the numerical model. Both advantages and disadvantages of parametric and non-parametric metamodels have been drawn for a specific engineering application.