My house was built in 1910. A few weeks ago while I was in the basement, I noticed one of the floor joist above me was not parallel to it's sister, but about 3/4" below it. The wood had split. I noticed that the portion behind it (about 2' to the wall) had an odd floor pattern with sloped joists running the opposite way, and realized that it was under the hearth. Ok, I'll have to jack that up and figure out how to reinforce it - the house IS old - so I got a jack, and after 3 weeks of half turns, I noticed the wood is constricting under the jack, not raising. So now that I'm actually paying attention... The sister joist also has cracks, but is not bowed. I start to really look at the fireplace construction. The chimney of my fireplace straddles the foundation, meaning on the inner portion there is no additional masonry underneath. The odd floor joist pattern is under the fireplace. Is this ok? My fireplace has always worked properly, the chimney doesn't lean, and I've never seen a crack. I have no idea what to do, and I don't have disposable income right now. (of course I can't let my house go to pieces either! I can't find any example of this type of construction, or how it was corrected.