You do not have to pay in cash.
However if the property is not habitable then a lender can require that the property be brought into habitable condition before a mortgage will be made on it.
An FHA 203K loan will allow you to buy and renovate the property.
You need only 3.5% down and you can finance all of the renovation costs too.
See the link below for all of the information on a 203k loan.
Cornerstone Lending Inc
215 674 9059