Figuring/estimating depreciation costs

[Webster Edpao]

Hi. First post. 😁

I understand that to determine depreciation, one takes the FMV minus the cost of the land and divides bu 27.5, correct?

However, how does one determine the cost of the house(alone) on the property? Is it public info on some county tax websites? Is there a way to estimate a home’s depreciation before purchasing it?

Thanks. I tried using search function and find a bunch of info on various depreciation predicaments but nothing on my specific question(but perhaps i am not searching correct terms since im a newb)