If your possession has been "adverse," you own it. Learn how long it takes to foreclose on a home in Illinois, the best way to avoid foreclosure and the 10 steps in the Illinois home foreclosure process.In Illinois, a squatter must live on the property continuously for 20 years before they can make a legal claim of adverse possession. Let's take a closer look at how to sell a house "as is" in Illinois, your options for getting an offer, and what to expect from the process. Squatter's rights in Illinois allow individuals who occupy a property without legal permission to eventually claim ownership under specific circumstances.