Re-installing block frame window
I am going thru a very large remodel at my house which includes adding a second story over the existing first floor. I hired a contractor to frame the addition. They took out about half of the windows on the existing first floor to install new headers. Now they are trying to tell me that I can't reinstall these windows because they are block frame windows and will not pass inspection if I use them in new construction. The windows are only 3 years old, so I do not want to purchase new windows.
After much going back and forth, they said that they could maybe reuse the windows by installing a fin that would nail around the outside, then they would be able to install and weatherproof with no issues... oh, but they want to charge me $1900 to do this.
So it looks like I will be reinstalling these windows myself. Are there truly any issues with installing a block frame window in new construction? To weatherproof correctly, do I need to track down these nail-on fins? Or is there another way?
Thanks for any help.