Investors & landlords

So to clarify - the water heater, new AC, etc will not be  added to the cost basis because I expensed them in prior years?  So my cost basis will remain as the cost that I originally paid to get it in 2010 (meaning 464K) and none of the improvements will be added because I expensed them in prior years - correct?  I keep getting information saying that I need to add them and then not add them so it's very confusing.  thanks!