Supply of building materials

A friend of mine is trying to raise funds to startup sales and supply of building materials. The plan is to start small then with time, once the business starts growing he plans on expanding it. How lucrative do you think this business can be?
Personally I feel it's an extremely lucrative business. There are lots of constructions going on, both personal and commercial. Setting up in a busy urban area would Definitely be worth it.

I have a couple of relatives involved in this line of business and they say it is profitable. The best part is you can get items on 90-120 days credit line but you can sell them for cash