Precast concrete slabs and their supporting walls are connected using dowel pins, anchoring loop bars, and cast-in-situ concrete. The design resistance of such connections can be calculated using multiple different methods. The design load bearing capacity can vary depending on the method used and assumptions made during calculation, making it difficult to determine, which methods are reliable and should be preferred. The study ordered by construction company JSC “UPB” discusses two design methods proposed by Eurocode 2 and fib Bulletin 43. A semi full-scale loading tests of concrete walls and slab specimens are carried out. The results show that the design methods considering only the contribution of steel dowel pins, underestimates the actual capacity of the connection by 2 to 4 times. On the other hand, the methods, considering both the contribution of the dowels and the friction between concrete interfaces, correspond well with the experimental results.