Good question.
I would think that it would depend on the particular financing instrument you use.
For example, if you go through a mortgage company to get it, and the financing instrument IS a mortgage, then I assume FICO would treat it as a home.
On the other hand if you went to your banker, and took out a loan with the land as collateral, I assume using the same logic that it would be treated as a personal loan, or maybe even a HELOC, or LOC.
Why don't you call up any title company and ask them?
My real estate expertise is long gone.
Perhaps Lady_Scarlet will see this and chime in.