Flat roof issues (single family house)

[Bienes Raices]

The REO I'm most interested in has a flat roof (that's the only negative that I can see about it). However my insurance agent said she only has two carriers who will write a policy for flat roof. I'm waiting to get more info on that tomorrow. Obviously if it's a huge insurance issue I won't be making an offer.

Does anyone have any input about flat roofs, pro or con? The only other information I have about the composition is that it says it's "built up" -- I'm not sure what that means.