The lower house of Congress, the US House of Representatives, doesn't get any say in treaties.
For a treaty to be ratified by the upper house, the US Senate, after which it has force of law equivalent to the US Constitution, it has to receive a 2/3 vote.
"The Iran nuclear deal" received that vote seventy years ago next week.
The US Senate ratified the United Nations Charter, which obligates its signatories to conform/comply with resolutions passed by the UN Security Council pursuant to Chapter 7 of said charter, on July 28, 1945.
A Chapter 7 UN Security Council resolution approving "the Iran nuclear deal" passed on Monday.