I took down the wall in my 250 year old home to discover a very large sill 8" by10". two inches up from the bottom and two inches deep is some type of rot. I can scoop it out with my finger.The wood gets hard about two inches up from the bottom and two inches deep. I suppose this is nothing to reinforce or rebuild since it such a small area but I would like to stop further rot.I will be putting a 10' sliding door in place of the wall.What are the best measures to protect my sill. Should I paint it.I do not mind being a little excessive or extreme for a peice of mind.