Every now and again a house will settle. This could be a problem or not, depending on how the columns that support the walls were constructed. As with frame building techniques, a foundation is required for building with post and beam. However the foundation serves a different function in post and beam.
In frame building the foundations support the walls which will be erected over them. In post and beam construction the foundations support the walls which will be constructed over them, too, but do not support the weight of the house. The weight of the house is supported by the columns.
The first step in post and beam construction is to locate the position of the columns. They should be placed on corners where interior walls join outside walls and about every three meters on walls which are "free standing". A column consists of at least two parts. There is a part which is underground and is called a zapata. The zapata is a steel reinforced concrete block on which sets the above the ground column. It is usually one cubic meter in size. This will vary depending on soil characteristics.
The zapata is usually the same depth in the ground as the foundation but not always. It can be deeper. The concrete in the zapata should weld the foundation and the column into one integrated whole. At times, the practice described here is not realized in the construction process.
If the soil is false and the zapata is not deep enough in the ground or is not integrated into the foundation, the weight of the house can cause the foundation to settle and this in turn will cause walls to crack. This settling can also cause floors to heave or buckle. Finding and correcting this type of problem can be costly and time consuming if you don't know what to look for.
The first step is to check to see if the corners of the outside walls are plumb. This can be accomplished with a simple plumb bob. If an outside wall is even • inch out of plumb, walls can have several wide cracks each of which is more than • inch wide. The next step is to dig alongside the foundation and see if the columns are deep enough. If not, then it is possible to add zapatas on the outside of the foundation and weld steel rebar into the existing columns and add whole columns where they are lacking.
All added columns must be connected by dalas tied securely into the rebar in the columns. It would be best to completely encircle the house or structure with new dalas, but this is rarely economically feasible. If there are walls which are not showing cracking, then it is possible to tie the new dalas and columns into the existing ones by opening the concrete enough to expose the rebar in them and welding the new to the old.
It is also possible to widen the existing foundation by filling a trench which has been opened alongside with rocks. Once the rocks are at ground level, an extremely liquid cement mixture can be poured over them. This process binds the new rocks with the old foundation, and it makes the soil stronger. Soil thus treated can support an additional 500 kilos per square meter.
Repairs of this nature are best left to people with experience. It is not a good idea to get your gardener or local albañil to realize this type of repair. Granted that a repair like this is expensive, but if it is not done properly, the expense will go for naught.
Mr. Worthington is a long-time resident of the area, a builder and landscape architect. You can contact Mr. Worthington at: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
