Legal Question in Real Estate Law in Illinois

The roof may or may not be a majore repair deoending on the scope. Your legal as opposed to practical right to not pay rent is governed by the lease terms.

I can't think of anything more major than a roof - however, if damage/wear to the roof is small, that might make it a judgment call.

In Illinois you may not withhold rent until all other avenues have been exhausted and probably not then. You can move out and stop paying. When he takes you to court you can argue that he broke the contract/lease by not fixing the roof. Lawyers will like you.

In some cases, you can stop paying him and put the money in an escrow account, then pay when the roof is fixed. Again, you have to hope the judge agrees with you, because he will probably sue.

You may not withhold rent to cover damage to your personal property. The major problem is valuation - and remember, the law almost never allows for replacement value. The value is what you could sell it for at a garage sale. You can not pay rent and counter sue for the value of damaged property when he sues you, but you are betting that a judge will see things your way.

It is too late, but the best answer is renter's insurance - it's like homeowners insurance for renters.