Foundation damage can occur for a number of reasons. Settlement, or consolidation of soil below foundation walls or footings is one cause. Lateral pressure exerted by soil or water is another. Sometimes damage occurs because of improper construction or deterioration.
Old stone foundations were typically constructed with a weak mortar consisting mainly of soil and lime. The primary purpose of this mortar was to fill the voids between stones so that vertical loads could be supported. Stone basement foundation walls are usually at least 18 inches thick (20 inches or more is common). Since large stones were often not readily available the walls were often constructed as two parallel walls with larger stones spanning across both walls to create a monolithic wall. If enough large stones were not used or if the mortar joints deteriorated significantly over time these foundation walls weaken and can bow, buckle, or fail.
The two photographs below show a foundation wall located between two attached dwellings. Both dwellings have basements so there is no pressure exerted on either side of the foundation wall from soil or water. It appeared that few large stones were used to bond the wall together. This resulted in excessive buckling and failure of one portion of the foundation wall. One half of the thickness of the foundation failed failed completely at one area. The other half is mostly intact, but was not able to support the weight from above. The brick party wall above did not fail completely because of the strength of the brick mortar joints, but the brick wall and the floors supported by this wall shifted an excessive amount. a structural inspection prior to this failure would have alerted the owners that a serious structural problem existed.
Block basement foundation walls often develop horizontal cracks at mortar joints and can bow or buckle inward. Occasionally block foundation walls can fail suddenly, as shown in the photographs below. This failure occurred following heavy rainfall. The lot was flat and surface water run-off was not directed away from the foundation. The owners had ignored a relatively wide horizontal crack. The approximately $30,000 repair cost would have been avoided if a repair costing less than $10,000 has been performed. Homeowners insurance does not cover repairs to damaged or failed foundations
The photographs shown below show one method of reinforcing block foundation walls using steel braces. Building Consultants, Inc. has successfully designed repairs for many foundation walls.
The photographs shown below show a method of reinforcing block foundation walls using Grip-Tite wall anchors. Building Consultants, Inc. performed evaluation of this foundation wall and the engineering for the repairs.