I just recently signed a lease for a townhome. Last week I was called by my landlord and told that he is going to sell the home. In our rental agreement (which is for 18 months) he added that rent can be raised with proper notice. My question is, since the new owner will inherit the rental agreement, how much of a notcie does he have to give us before he raises the rent and if we can't afford it can we move out? BTW I live in Colorado.

First I have to say not much of a lease if they are allowed to raise rates, normally a lease is suppose to lock your payment in for the term of the lease,

But if all they say is "proper" than they have to give a "proper" notice.
That will have to either be agreed to or end up in court since the lease did not specify the terms.

If I had to guess and it allows them to raise rate 30 days would be "proper"

It sounds like it was deceiving you in the first place by doing it that way. May had plans to sell the place but was not forthcoming with you and I consider that not acting in good faith and fair dealing. You could send him a letter asking him if he had plans or already contacted a realtor about this and if he was heing honest with you. Most leases do lock in price so I am surprised you clal this a lease. What was heis reason for this to be added in lease.