A Large Crack Suddenly Appears in the Corner of a Foundation after a Long Dry Spell GENERAL INFORMATION Name of Homeowner(s): Mr. and Mrs. Taylor Homeowner(s) Phone No: His Work #: (704) 534-5994 Date and Time of Fact Finding Investigation: August 14, 2000 @ 10:00 - 12:00 p.m. Weather Conditions: Sunny, 85° Parties Present at Fact Finding: Mr. and Mrs. Taylor, Joe Smith of S & T Homes, and William Stanton Are Homeowners the original occupants? Mr. and Mrs. Taylor purchased the house new on July 29, 1994. Items Observed and Measured: Rucking in the taped sheetrock joint in the interior corner of the living room (Photo 2). Crack in the foundation curtain wall on the rear elevation, in the left rear corner of the house (Photo 3). Orientation: Unless otherwise stated, all directions (left, right, rear, etc.) given in the report are in relation to an observer facing the front of the house. | Top | Table of Contents | BACKGROUND The house was constructed in 1993. Mr. and Mrs. Taylor purchased it in the summer of 1993. They lived in the house for 6 years and did not have any problems with cracks. In 1999, it was very dry during the summer. In September 1999, a 5/8"" wide step crack appeared in the left rear corner of the foundation curtain wall. The Taylors reported the defect to AIC. Between the end of September and November, it rained a lot and the crack closed up. The Taylors contacted AIC again and reported that the condition had corrected itself. In July of this year the crack reopened and the taped joint in the corner of the living room rucked. On July 24, the Taylors contacted AIC about the condition. | Top | Table of Contents | DESCRIPTION OF PROPERTY The house is a wood-framed, two-story structure, approximately 2600 sq. ft. in size (Photo 1). It has a two-car attached garage. The exterior walls are clad with hardboard siding. The interior walls and ceiling are sheetrock. The house has a crawl space with a pier and curtain wall type of foundation. The ground immediately in front of the house is relatively flat, and then it drops off rapidly to the street. The ground on the sides and rear slopes toward the rear of the house. There is satisfactory slope away from the foundation on all elevations and no observable drainage problems. | Top | Table of Contents | METHOD OF INVESTIGATION At the beginning of my investigation, I interviewed Mr. and Mrs. Taylor about the history and location of the reported conditions. In the company of the Taylors and Mr. Joe Smith I then inspected the living room walls, focusing my attention on the corner where the taped joint was rucked. After that, we looked at the crack in the curtain wall. I went into the crawlspace to look at the conditions on the inside of the foundation wall. Since the problem appeared to have been caused by swelling of the soils around the left rear corner of the house, I paid special attention to the drainage patterns around that part of the house and in the crawl space. | Top | Table of Contents | OBSERVATIONS The taped joint in the left rear corner of the living room is rucked due to structural movement at the corner of the house. There is v-shaped crack in the brick curtain wall on the rear elevation in the left rear corner of the house (Photo 2). I measured the crack and found it to be 3/8"" wide at the top of the foundation and 3/16"" wide at the ground. The curtain wall in this location is somewhat weaker in comparison to the other parts of the curtain wall because of the proximity of the vent and access door openings (Photo 2). The fact that the crack is wider at the top than at the bottom indicates that the corner of the foundation has rotated downwards. Another indication that the corner has dropped is the 1/8"" wide space between the top of the corner pier and bottom of sill band. The ground in the crawl space slopes toward the left rear corner of the house. A PVC drainpipe is located in the corner to drain excess water out of the crawl space. | Top | Table of Contents | FINDINGS AND CONCLUSIONS Since the ground in the crawl space slopes toward the left rear corner, water would tend to accumulate in this corner and seep into the ground. Thus, the soil around the corner pier would tend to contain more moisture than the soil around other piers. The fact that no cracks occurred in the foundation for 6 years is a strong indication that the cause of the problem is not settlement. Instead, the relative sudden appearance of the large crack after a prolonged drought indicates that the cause of the problem is shrinkage of the soil due to loss of moisture. According to soil maps produced by the U.S. Dept. of Agriculture, the soils in this subdivision contain significant amounts of clay and therefore have shrink-swell potential. Cracks in foundations that are caused by shrinking and swelling soils are common in the Charlotte area. In summary, it is my opinion that the crack in the corner of the foundation was not caused by settlement of uncompacted soil. Instead, the evidence points toward shrinkage of the clay soil around the pier as the proximate cause. The root cause is dry summer conditions. The structural integrity of the corner of the house has not been significantly compromised. The pier will probably move back into position when the moisture content of the soil increases by either normal rainfall or purposeful watering by the Taylors. | Top | Table of Contents | LIMITATIONS The observations described in the report are valid on the date of the investigation and were made under the conditions noted in the report. We prepared the report for the exclusive use of AIC and their successors and assignees. Criterium-Stanton Engineers does not intend any other individual or party to rely upon the report without our express written consent. If another individual or party relies on the report, they shall indemnify and hold Criterium-Stanton Engineers harmless for any damages, losses, or expenses they may incur as a result of its use. The report is limited to the visual observations we made during our inspection. We did not remove surface materials, furnishings or equipment, undertake any digging or excavation, or perform any destructive or invasive testing. Accordingly, we cannot comment on the condition of systems and components that we could not see. In addition, we are not responsible for conditions that were not within the scope of our services at the time of inspection. We did not assess the stability of the building or the underlying foundation soil since this effort would require excavation and destructive testing. We did not perform any computations or engineering analysis as part of this evaluation, nor did we conduct a comprehensive code review. This report should not be considered a warranty of condition, and no warranty is implied. | Top | Table of Contents | William A. Stanton, P.E. | Top | Table of Contents | | Structural Inspections | Residential & Commercial Services |