The present disclosure is directed to a root assembly for a rotor blade of a wind turbine and methods of manufacturing same. The root assembly includes a blade root section having an inner sidewall surface and an outer sidewall surface separated by a radial gap, a plurality of root inserts spaced circumferentially within the radial gap, and a plurality of spacers configured between one or more of the root inserts. Further, each of the root inserts includes at least one bushing surrounded by a pre-cured or pre-consolidated composite material. In addition, the spacers are constructed of a pre-cured or pre-consolidated composite material.