I have a contractor renovating the exterior of my 1920's home. After the siding was replaced (original contracted work) we decided we would like to go ahead and replace the outer trim on the windows as well. The contractor provided a change order (#1), we agreed on price, and we both signed. I paid the required payment (50% up front) and the work began that day. We looked at the windows with the sub-contractor and GC at that time and discussed that we would need to add underlayment OSB in order for the trim to be level with the siding. The work began and one of the workers got very sick and had to go home. Since the project was already way over time and I have previous construction experience, I jumped in to help with demo of the old window trim and to act as another set of hands for the subcontractor and keep on schedule. When the work was complete, the GC brought me a new Change Order (#2) to sign and pay for an extra $3000 of labor on the window trim when the original signed change order was $1750, bringing the total amount to $4750 + 20% overhead. We never agreed to pay more or add any scope of work to the work in change order #1. He said he was charging extra for demo of the window trim (which I did), adding OSB under the trim (which we believed was included based on conversations at the initiation of work) and adding tyvek to the windows (which I did for >50% of the windows). I told him that the price was outrageous, that we didn't agree to any extra work, and I did much of the "extra" work that he was trying to charge for. Our contract states that any changes will be agreed upon prior to work starting and that both parties will sign, and payment will be made. Based on this clause, I do not believe that I need to pay this bill and told the contractor. We tried to negotiate with him for a total of over 6 hours on 4 different occasions and he wouldn't budge on his price or insistence that we owe him. Every time we say, we didn't agree to this, he claims that the change order clause in the contract doesn't matter. Now he has walked off the job and has left us with a gigantic mess, >6K in unfinished work, and several quality issues in the work (he shot nails through electric wires so several circuits in our home no longer work, windows are now crooked in their frames, etc). The even bigger problem is that he has left our raw wood siding unpainted and we are concerned about the effect on the wood. We suspect that he mismanaged the funds we paid him and is trying to add money to the budget to compensate. Who is in the right on the change order? What remedy do I have?