I have recently bought an older property which still has some of the old sash windows still intact, all be it some have been painted nailed and screwed shut, some all three. I have began with one of the windows after eventually removing all the screws and nails etc , and taking out the sashes I have stipped the wood of paint and taken out the glass. the one sash had minor damage to one of the joints which I have fixed by redilling gluing and dowelling the joint. The other sash however has quite extensive wetrot where the bottem rail met the sill. I have again stripped back all the paint and removed the glass. I have also taken away all the decaying loose wood back to a sound base and applied a wood hardener do consolidate the remaining part of the sill. My question is because of the extend of the damage around half he bottem ail rotten should I try and splice in a piece of wood, before filling and sanding or use some othe method, I'm thinking it might wok out too expnsive to attempt to build up filler fo the whole area.