What does this sentence mean?
The houses for ordinary people aren't built of such material as is the King's house.
I don't understand this structure, especially as.
"As" is used when we compare two things, one of which is superior. In the sentence in question, the material that composes the houses of kings and ordinary people is compared. The statement simply tells us that the material used in the houses of kings is better than that used in the houses of ordinary people.