Please forgive me, I am new on this site.
I currently have a home that was built in 1824 2 story balloon framing style, I think. The house has been changed over the past 191 years and one time exterior walls are now interior walls. I noticed about a month ago some cracks in the corner of doors and base board in two joining rooms. I did a little investigating in the small basement and noticed the rubble stone foundation has never been re-pointed. Since it's winter and warm in the basement, I have started the process of cleaning out the old lime mortar and re-pointing it back. After working in the basement a few nights, I started looking over the sills and noticed an area about 10'- 15' long has rotted away. So my question is, can I replace the deteriorated sill without jacking up the wall or adding support? can I replace the sill in small 6' sections with out supporting the joist or studs? I can't get to the backside of the foundation, very small crawl space with dirt floor. This sill is located in the middle of the house and never gets wet.
Thanks for any suggestions