Double Taxation on ROTH IRA contributions for down payment

[Chris Fore]

I have a solid ROTH IRA and I was interested in using some of the contributions as the down payment on a property. That money has already been taxed (as per the definition of a ROTH IRA). However, once that money gets tied up in the property as equity, when I sell that property down the line, will I pay taxes again on that money?

I was asking a realtor friend and he didn't have an answer.  

Obviously I'm not looking for "official" tax advice but does anyone know the answer off hand?