Why do you need this job?
The interviewer asks this question to see what your motivation is to work. It might be that you need this job to support your family, save for a house, or pay your bills. It seems like a silly question to ask, but the interviewer wants to ensure that you don't need this job until something better comes along. They want to hear that you are enthusiastic and excited about roofing and plan to stay with the company for the long term. Explain your reason for needing this job.
Avoid saying that you don't need this job or that you need this job until you find something different. If you sound uninterested in this job, the interviewer will assume you will not be a reliable employee and might pass you over for another candidate with more enthusiasm.
"I need this job because I am a Roofer and do not want to work in another industry. I have a new baby and need this job to support my family while my wife stays at home with her."
