U Value Calculation

Need to calculate the "U" vale of the whole system of roof slab and to find out,whether the U value reaches 0.14W/m2K for the whole system. The whole system include 1. Structural slab (Concrete) 2. Water proofing WPS-B301 (BITUMEN),Thickness 27 mm 3. Fiberglass insulation (Density 112 kg/m3,Thickness 225 mm and K value 0.034) 4. Screed,Thickness 75 mm Please advice me the calculation proceedure