Fireplace Not Properly Insulated?

[Kevin Barrett]

I sold a new construction SF home a few years back and just received an email (see below) that the fireplace is not properly insulated. I'm looking for advice in responding. The picture is the actual fireplace. Happy New Years!

Email:

I was hoping to get your feedback regarding an issue we recently found with our fireplace at our house. We have always noticed a big draft coming in through our fireplace. I was talking to a friend and he mentioned they may not have insulated it properly. We pulled off a little bit of siding and could see that they did not insulate the floor. Based on pictures we have when the house was built (2011) it looks like they probably didn't insulate the walls around the fireplace either. I can't confirm that without pulling down a great deal of siding, sheathing, etc which I am not comfortable doing.

I know the warranty has expired so we won't be covered under that but the walls/floor around the fireplace, as built, were not up to the building code. We know we are loosing a lot of heat due to this and it could impact resale value. Is this something that the builder is obligated to fix or has too much time passed?