Hey. I'm a joiner and see this alot. I don't think that the conservatory would be in mahgogany as it would have cost you tens of thousands. It could be sapele or utile cheaper mohog lookalikes. You should call a local joiner and get him to quote you for a cill replacment, and for the corner post, depending on how bad the rot is. For a repair and patch. It depends how bad the rot is though. Hope you get it sorted
Toff54, May 2009