What is the proper way to attach base shoe molding on a hardwood floor?

Attaching base shoe molding primarily to the baseboard is the recommended approach because it helps to create a clean and finished appearance where the molding meets the wall and floor. When the base shoe is secured to the baseboard, it allows for necessary expansion and contraction of the hardwood flooring beneath without being rigidly affixed to it, which could lead to damage or disruption as the wood responds to changes in humidity and temperature.

Additionally, this method helps maintain the integrity of the hardwood floor. If the shoe molding were nailed directly to the floor, it could restrict the movement of the flooring and potentially cause warping or buckling over time. Attaching it only to the baseboard also simplifies removal and replacement if necessary, without damaging the flooring. This technique balances aesthetics, functionality, and longevity of both the molding and the hardwood floor beneath it.

Using glue or a combination of nails and glue, while they might seem like more secure options, could lead to complications when attempting repairs or replacements, as well as potential issues with wood movement.