(exp, v5s) to do something useless; to paint the lily; to gild refined gold; to build a roof atop the roof
→Related words:
屋上架屋
同じことを何回繰り返すの。屋上屋を架すようなくどい説明は勘弁してよ。
You're wasting your time with all this needless repetition so spare us the long-winded explanation.