宅

Roof radical on top — the indexing semantic. 宀 pictures the eaves and ridgepole of a dwelling. 宅 is specifically a residence, a private house, so the roof radical is doing direct semantic work. Joins the architecture family: 家 (home), 室 (room), 安 (peace at home), 寒 (cold shelter), 寄 (lodge with someone).

Bottom component supplies the sound, tuō → zhái with initial drift. 乇 itself pictured a young plant pushing up through the ground. As a phonetic it organises a small but useful family: 托 tuō (entrust), 拓 tuò (open up), 咤 zhà — sharing the same simple stalk-shape but spreading across several rimes.