Is it appropriate to contact the construction employer after a week or so if you haven't heard anything, especially if you were one of the top contenders for the position?

Absolutely. Hopefully you have already sent a thank you letter and/or email to all of the people you interviewed with. Depending with whom the interview ended, a phone call to either the interviewer or human resources contact is perfectly all right. Ask where they are in the decision process and reiterate your continued interest in the position.