Joist repair: Jack up and go under, or take out floor?
In the house we're hoping to get, the 20x20 two-story rear section needs to have the first floor joists repaired/replaced because they're sagging. That section is around 200 years old. The crawl space is VERY low, crawl-on-you-belly low, so I figure it will need to be jacked up considerably to get enough room to fix things. But most of te first floor is the kitchen, which makes me very nervous about having it jacked up that much.
I know NOTHING about this kind of construction work, but it dawned on me that it might be easier if I just tear out the kitchen floor and subfloor and have them do the work from above. I was planning to install new subfloor on top of the old floor anyway. I thought this might allow them to work between the joists to get them sistered, replaced or repaired, and secured. I could then put in some insulation and vapor barrier before I put down the new subfloor.
Would someting like this work, or am I missing something or totally not understanding how a project like this would be carried out?
And just as imortant - does my taking the floor out for them to work on the joists potentially (a) reduce the risk of damaging any of the rest of the features (such as the fireplace) and (b) reduce the potential cost since they won't have to jack it up so far or work in such a confined area?