Rental revenue and house valuation for sale/refinance

[Roger Simons]

Say you take your typical 3 br medium sized house that would typically rent for about $1500 and because of room conversion (like converting the living room/dining room/rec room/laundry room/den/etc) you now have a 6 br house and you're now getting double that and have months of proof of that.  Or years. 

Would an investor pay much more for this knowing you've just cleverly managed the space and the house itself really isn't much different from when you bought it?  

What about a bank?

Would anyone value it more for the revenue?  Isn't that what people buy businesses for in the first place? For instance in my area that typical 3 br house would sell for about $250,000.  And it would rent for about $1500.  And rooms here rent for about $500.  6 x $500 = $3000 or $36,000/annually.  At a 10% cap rate (omitting expenses which would be mostly shared) that $250,000 house is now $360,000.  Isn't a 10% cap rate particularly generous?  Wouldn't most investors jump at that?  I hear banks just look a appraised value which seems particularly short sighted.  Maybe other lenders loan on revenue more?