Roof Tile question

I am in the process of ordering roof tiles for a home with a roofing supplier. He is going to have to drive a few hours to pick them up from the manufacturer.

The question I have is, if I order 4000 tiles and when they deliver the tiles there are 100 broken ones that I can't use, how is this normally handled in Thailand?

Do I have to order extra tiles knowing that some may break or does the roofing supplier or manufactuerer give you some sort of breakage allowance?

I hope the question is clear and would appreciate hearing what people have experienced. Thanks

You have to allow for breakages, although generally most of the broken ones can be used on the edges anyway.