Ideally, houses are constructed to be plumb -- built evenly to a straight vertical line running 90 degrees from the horizontal plane. Think of your house's foundation as that horizontal plane. Everything rising from it, like the studs in your walls and the sides of your door frames, are meant to follow this plumb line. When your house's foundation shifts, your house is falling out of plumb and toward the horizontal plane [source: Nash].
When this shift occurs, the effects can be dramatic. Usually the first indicator is cracks in the house's masonry or concrete slab foundation. If you walk down to your basement or crawlspace, you'll find that the walls are likely made of cinder blocks. This is the masonry foundation upon which your house is constructed. It provides the support for everything else found above ground. If you find a massive piece of concrete instead of a basement or crawlspace, you have a slab foundation. Regardless of what kind of foundation your house has, if the soil beneath it shifts, cracks will appear.
Cracks aren't a dead giveaway of house settlement, however. Foundations are subject to other pressures that can lead to cracks. For example, in cold climes the seasonal freeze and thaw can cause rigid materials like cinder blocks and concrete to expand and contract, eventually leading to cracks. While cracks in the foundation aren't generally a good thing, those caused by seasonal pressures can be patched.
While some small cracks can be the result of seasonal changes, new cracks -- especially several that appear at the same time -- warrant attention. Old cracks that suddenly grow larger or any cracks that reach about one-quarter of an inch wide are also big indicators the house's weight is shifting downward [source: HouseMaster]. With wooden frame homes, walls may bow from the pressure exerted by settling since wood is somewhat pliable. Walls made of brick or stone are much more rigid and will display cracks more easily.
Other indicators of settlement are perhaps more alarming. Downward movement can result in those water and gas pipes snaking throughout the house to become twisted. You'll notice pretty fast if a water pipe becomes twisted; it can burst and flood your house. A gas pipe break is less easily detected and more dangerous. If you notice the pipes in your house bending, you've got a problem. Doors and windows are also a good indication that your house is settling. When they fall out of plumb, it can be difficult to open windows and doors since they've become angled instead of vertical.
If your pipes have burst, cracks are appearing out of nowhere in your foundation and you can't open a window to save your life, it's definitely time to call a professional. Foundation restoration companies locate the problem area beneath your house, excavate around the footing (found at the corner of the foundation), and install screws, which are like heavy-duty versions of the ones used to raise a car with a flat tire. Since the jacks are installed down to the bedrock or extremely compact soil, they act as extra support for the foundation. Additionally, subterranean foundation walls that are leaning inward can be anchored into the dirt beside them and gently pulled back into plumb.
Of course, if your home's been inspected and no telltale signs of settlement have been found, but you still hear those mysterious noises at night, then perhaps it's time to call a paranormal investigator.
For more information on home repair, ghosts and other related topics, visit the next page.