Hey guys, I began to notice after opening some windows in new house that owner never opened in years I believe and when I cranked open the casement window's sash the bottom was so rotted it just literally crumbled and the bottom of sash frame split in two! I looked at bottom of other sash of this window and the entire bottom is discolored a black color. The windows are Pella casement windows that are wood in inside but metal on outside & are original to the house built in 2001, so not THAT old right? I looked around other windows in house and the other Pella windows all have a slight discoloration near the bottom inside corners of sashes but not too bad. Currently waiting for a quote from Pella on sash replacement. Here's the pics from my write up to Pella below: A) Is there a way to seal the wood on the other ones so I can get least another 10 years on them or so? B) What typically causes this dark discoloration and how can I prevent it? C Is this black crap mold?