The objective of this thesis is structural design of floating garage in accordance with the rules of Det Norske Veritas classification society (DNV). In the concept phase general arrangement plan of garage was made on which topological positions of primary supporting members, bulkheads and pillars were developed. Furthermore, for the proposed topology, the calculation of structural elements of cargo decks, pontoons and ramps, considering local scantlings, was performed according to the rules. In the preliminary phase the partial model of the floating garage with finite element method (FEM) was created in software MAESTRO in order to perform initial scantling determination of all elements considering the yield and buckling strength criteria and permissible deflection. Then, the structural analysis of internal ramps was performed on the basis of separate FEM model and scantlings of associated structural elements with regard to the adequacy criteria and permissible deflections were determined. In the final phase, on the basis of scantlings obtained by the response of partial FEM model, global FEM model of floating garage was created. According to critical loading conditions, final calculation of structural response was carried out and inadequate elements were resized in order to meet all the structural adequacy criteria.