Many historic homes foundations were constructed without any consideration for the weight above. The hallway walls are almost always load bearing. One wall is constructed with a girder and supporting piers underneath, and the other with nothing but air. Over the years the unsupported wall as well as the floor will sag and bow down. It can also pull down the roof.
In some homes, the girder was placed down the middle of the hallway, and both hallway walls are unsupported. This can easily be detected by realizing that the middle of the hallway will have a hump in it. In some cases, the load bearing wall was built over a single floor joist; the wall is too heavy for the joist, and the joist will need to be doubled-up to better support the weight above.
In older pier and beam homes sometimes the girders are missing. You might see nothing but a sill plate under the load bearing walls. The floor joists, flooring, and walls, all rest on this flat piece of wood called a sill plate. The plate can bend like a rubber band, causing the floor above to sag and bow. A girder must be added that will support many joists together, and evenly.
Another problem in older homes is called point load deflection. With large historic homes, a lot of second story weight is transferred to the first floor through the walls. However, if there is no wall, but instead a header to transfer the upper weight, then the weight is usually sent to one side of a door frame. All this weight then pushes down on the doorframe. That point load rests on the floor, and the floor has no direct support under that exact point, except for air. The floor, over time, will bow down, usually within a small area.
If you have an older or historic home that you are concerned about, call Quality Foundation Repair for a free consultation and estimate.
