The construction radical and the construction kanji are the same!
This kanji also means industry, which is what construction is, if you think about it. It's all part of the construction industry.
For kanji that use the こう (there are a lot of them!) we will use the character こういち every time. He's one of the people who started this website, so we'll do our best in the mnemonics to embarrass him as much as possible. Anyways, remember that whenever you see こう, think こういち.
You see some construction in front of you. There, standing shirtless (only a suspender and hard hat) is (こういち), looking back at you.