Albert Barnes Commentary 1 Kings 7:1

"And Solomon was building his own house thirteen years, and he finished all his house." — 1 Kings 7:1 (ASV)

Thirteen years - The thirteen years mentioned here are counted from the end of the seven years it took to build the temple (1 Kings 6:38). Solomon’s building projects therefore occupied him for twenty years in total (1 Kings 9:10; 2 Chronicles 8:1), from the fourth year of his reign to the twenty-fourth. The difference in the time taken to build the temple versus the palace can be accounted for by two factors:

1. The long period of preparation that preceded the actual building of the temple (1 Chronicles 22:2–4; 1 Kings 5:13–18).
2. The greater size of the palace, which consisted of several large ranges of buildings (see the next note).