house
厦 centers on a large, solid building: a house or mansion. The meaning is straightforward and concrete.
厦 is the simplified form of 廈. The traditional form combines 广 (building) with 夏, likely contributing sound and the idea of a large structure. The modern form replaces 广 with 厂, but the building association remains.
The outer 厂 looks like a roof or cliff shelter, and inside is 夏 (summer). Imagine a sturdy house that keeps you cool in summer: 厦 is a house.
For カ, picture a house so big it could fit a car inside: car -> カ, and the house is spacious enough to park it.