Your house foundation.
It is what holds your house nice and level and keeps it from sliding down driveway and out into the street.
Foundations in new construction are designed for the slope of the land, as well as soil conditions, numbers of stories and other factors. Not long ago I inspected a home where, way back around 1900, four trees had been cut off on the site and these cut-off trees became the four corner supports for the home. In the following picture one can see one of the tree stumps that is now surrounded with “additional” foundation that has been added over the years.
Yes it was very small and was most likely nothing more than a get-away cabin that was built before the area became overrun by “progress.”
A tree is a relatively good analogy as to how foundations work. We have the support post (the trunk of the tree) and the footing (the roots that spread the load out over a bigger area). Any tree, when impacted by forces it was not “designed” to deal with, can become uprooted and the tree will topple over. The footing of trees is pretty much designed to secure the tree in place and counter the forces placed upon it by wind. A bunch of trees together will do more to help each individual tree than any lone tree can do.
A house foundation is similar. If it is supported by four corner supports and we loose just one of the supports bad things are likely to happen to the furniture, and occupants---never mind the structure itself. Now if we divide the spaces so we now have 8 supports, we go from catastrophic failure to something in between “catastrophe” and “sloped-floors”----commonly referred to as “character.” If we divide those spaces again, we now have supports at 16 points and it becomes even less likely that loss of one of the supports is going to be as problematic. Of course this is all relative to the distance between the supports and the type and size of beams spanning those supports.
Obviously if we fill all the spaces between the supports we have what we call a continuous foundation and some of that foundation could be effectively taken away without much consequence to the whole house. If one thinks about a foundation in this manner, it makes it easier to understand how inconsequential some cracks can be. Of course one still needs to be able to interpret the cracks----because they could mean something more.
We still have a fair number of post & pier type foundations around the NW that were built around the turn of the century----the 20th century. They almost always have inadequate supports even though the spacing of the support posts would likely be adequate by current standards. What was usually NOT adequate however was the size of the footings under the support posts. Lots of times these posts were simply placed on large stones----including both stones found on site as well as cut blocks of stone brought to the site. Sometimes they were merely set on blocks of wood----or as previously stated---tree stumps.
These houses almost always have “excessive character” that would not be tolerated in any other type of construction. The best solution almost always involves either replacing the support post footings with ones engineered for the soil conditions (always considerably bigger than the ones originally used) or install an actual full foundation under the home.
These post & pier homes can be very difficult types of houses to “fix.” Fixing usually involves making a decision about whether one can live with the amount of sloping of the floors or not. If one cannot, and the house is to be leveled, factoring replacement of all the lath and plaster throughout the home will become a necessity as opposed to staying a cosmetic “feature” of the home. This gets really complicated if the house has undergone interior work to counteract some of the settlement. Floors that had been leveled to compensate for the sloping may now become out of level. Windows and doors installed level and plum will now no longer be level and plum.
Most people opt for simply “stabilizing” the home with proper supports and/or foundation and bank on retaining the cosmetic “features” and “character” of the home.
At a recent inspection all or most of the support footings had been “upgraded” at some point in the past---maybe 50 years ago. Because these footings were undersized and located so that the post was not centered above them the house has continued to settle and is about to play tiddlywinks with the footings.
These supports will need to be re-done or a new foundation poured under the house----they did not succeed in stabilizing the house at all with this repair.
Charles Buell
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DeCroe, is my "ethereal" home inspector assistant and occasionally flies into my blog and other people's blogs to offer assistance. To find out more about her beginnings just click on Raven.
