Is it considered unlawful for a wife to work as a civil engineer if the family is not in need of money?

If a woman is provided for financially and her husband prevents her from working, and she did not stipulate this condition before the marriage contract, then she must obey him and refrain from working. This is because obedience to him in what is good is obligatory, and a woman’s being in her home is better for her than her going out to work or for other purposes.

Allah Almighty says: "And abide in your houses and do not display yourselves as [was] the display of the former times of ignorance." (Al-Ahzab: 33).

If the woman wishes to work, she can try to convince her husband to allow her to work in a place that does not violate Islamic law.