Construction material supplier/retailing business

Dear folks,
I am considering to start a construction material supplier or retailing business (cement, crush, maybe steel bars, etc). I have no idea about potential margins/profit. Could anyone please give me an idea what profit should i expect with how much investment?

Jazakallah

Yeh badmasho ka kaam hai. Too much headache.... You have to be available 24/7. Ready to take material back on your expense.

Late payments is a big issue.

If you can manage all that than margins are good. 20% to 30% earnings are easily achievable

Thanks HT for your reply.

I am considering this business because of

1 - In parallel I am thinking to start home construction & Selling business.

2 - 24/7 Availability is not required

3 - Less headache of invoices payments.

But as you mentions point 2 and 3 can be major issues in this business. Is there any business remains for a shariff Admi like me who have no higher ups connections nor a business experience?

Your inputs please