side room
簃 refers to a side room, a small room attached to or beside a main building.
簃 combines 竹 (bamboo) with 移, which likely contributes the sound and the idea of shifting or moving, suggesting a bamboo-built side room or annex.
The bamboo top 竹 suggests a bamboo structure, and the bottom 移 (move/shift) hints at a room shifted to the side. Picture a small bamboo side room attached to a house.
For イ, imagine an eave (イ) of a bamboo side room extending from the main building: eave -> イ.