Answers (1)
bal·last
ˈbaləst
noun
1. heavy material, such as gravel, sand, iron, or lead, placed low in a vessel to improve its stability.
2. gravel or coarse stone used to form the bed of a railroad track or road.
verb
1. give stability to (a ship) by putting a heavy substance in its bilge.
"the vessel has been ballasted to give the necessary floating stability"
2. form (the bed of a railroad line or road) with gravel or coarse stone.
~google.com
So what are you talking about?
To answer your question, the only sensible thing to do is contact a roofing contractor and ask for an inspection and a bid.