We went to see the Azay-Le-Rideau chateau in the Loire Valley last week, only to find out upon arrival (and after an hour drive) that the exterior is under renovation and is mostly covered in scaffolding and and drapes. From the guidebook, it sounds like the exterior is the best thing to see (fairytale-like) so we were pretty disappointed, as the interior isn't as interesting compared to other chateaus -- in case you don't want to go out of your way for it. They are offering a discounted rate during the renovation.
It sounds like it started some time this year (assuming after the 2015 book was printed?) and the first phase will be completed next year, with the second phase taking until 2017. I know the RS staff sometimes looks at these posts, so maybe the book can be updated to reflect this?