The CWCki states it was mortgaged for a second time for $130,000 in April 2009, which was apparently more than it was actually worth. The Chandlers had paid off the original mortgage sometime before February 2009, but re-mortgaged it in April 2009 to pay off Barb's credit card debts. It hasn't been paid off fully because Chris had the habit of paying the bare minimum on it every month, instead spending money on toys, videogames, junk food, and that book he used as a guide for fucking his mother.
I used an inflation calculator and with inflation, the mortgage would be worth $179,551.45 if it was taken out today. The house is very likely worth far less though, due to the very poor condition it is in, and the fact that prior number was above the house's value.