It becomes a important to describe some construction methods of the late 1800 period. Conventional framing today would construct a house by building a platform for the floor, followed by supporting walls, followed by roof trusses or another platform for second floor. This system is usually called conventional or platform framing. The main advantages in conventional framing is that the length of the pieces can be shorter and that the floor platform distributes the forces more uniformly.
However, there was a time when trees were plenty, tall and straight. In these days a 24 foot 2x12 was not in scarce supply. In those days it was common to build a house either with large timber beams, or the other method of the time was called balloon framing. In this method the exterior wall is built directly on the foundation and the floors were attached to the wall members. The primary disadvantage in this system is that the wall pieces were long (thus added cost as time progressed) and also that the vertical stud could be under significant loading (because they carry point loads instead of distributed loads).
Our house was built in the 1890s and is a very good example of balloon framing. However, it has for many years sat with the front wall being in direct contact of the dirt and grass. This I am sure would have resulted in extensive termite damage except that there was plenty of other dead wood in the yard. However, the damp rot mad a good spot for borers and other opportunistic bugs to chew or dig away the structure. When we raised the house, removed the lathe/plaster and removed the lower section of the siding it was clear that while the damage was substantive, it did not go beyond the damp rot area. For this reason it was important to remove the damaged section and repair/replace. This is why the balloon framing has a downside, as significant damage to a section of studs could cause the wall or house to collapse.
I decided very quickly that it would be cheaper and safer to replace the wall than to repair it. The entire side of the house was sagging perhaps 2+ inches. First we installed a few beams across the joists of the second floor and carefully jacked them to remove the loading on the studs. At this point is was critical to establish a planar point of reference in order to find dimensions of the replacement wall. This was not all too difficult as we have replaced the foundation and the sill is level around the perimeter. The side was again raised sufficiently to something around level. At this point I discovered that the wall was not vertical but a parallelogram. It was off by about 3 inches from vertical on only the wall we are replacing. This of course can be corrected by using a hoist or simile pulling device to pull the opposing corners back to straight. What you see here is the replacement wall built and in place with the internal sheathing acting as bracing for the wall. It is not quite finished, but it gives a good idea about both the process and the result. After finishing up the replacement wall in the next week or so, the next project will be to complete any other planar adjustments to ensure that each floor, the exterior and of course the members are as level as can be reasonably accomplished given the limitations of the existing materials.