Buying thirty year old SMH as a rental investment

[Parag D.]

I am looking at a couple of single family home investment properties in my area and wanted to know how old is too old as a rental property? The houses are built in 1990-1995 range. Some have improvements made like changed roof etc. These houses net around $300 cash flow per month.

If there are any rule of thumb or things I should consider before investing in these older houses.

Thanks in advance.

Parag