Jamieson, Fausset and Brown on Ezekiel 41:5

5. side chamber--the singular used collectively for the plural. These chambers were appendages attached to the outside of the temple, on the west, north, and south; for on the east side, the principal entrance, there were no chambers. The narrowness of the chambers was in order that the beams could be supported without needing pillars. The plan is similar to that of the hall at Koyunjik, a large central hall, called the oracle, with smaller rooms built round it.