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• 4.0 CONCLUSIONS It is BCI's professional opinion that the distress to the Barker residence is the result of a combination of factors, including possible sinkhole activity. Based on the results of our investigation, the minor cracking distress to the house is primarily due to minor differential settlement of the foundation related to the long -term densification of the very loose to loose sandy soils that locally support the structure. In addition, we found evidence of unstable and possibly raveled soils in two of the three SPT borings completed at the site. Given these subsurface conditions and the apparent on -going cracking distress to the house, we cannot rule out the possibility that sinkhole activity may be affecting the structure to some extent. The analysis described in this report is of sufficient scope to identify sinkhole activity as a possible contributing factor to the damage within a reasonable, professional probability, as defined by §627.706 -707 Florida Statutes. Primary factors in our conclusions include the following: • Evidence of unstable and possibly raveled soils was encountered in borings SPT -2 and SPT -3. Intervals of very loose (weight -of- hammer) soils were encountered from 33'/2 to 371/2 feet below grade in boring SPT -2 and from 331/2 to 381/2 feet below grade in boring SPT -3. In addition, a loss of drilling fluid circulation was recorded in association with the strata transition interval in boring SPT - 3. When these subsurface conditions are considered in conjunction with the apparent on -going cracking distress to the house, we cannot rule out the possibility that minor ground settlement associated with active soil raveling and a developing sinkhole condition may be impacting the residence to some extent. • Based on our test pit excavations, the foundation for the house is embedded at a depth of approximately 18 inches below grade and the screened porch slab is embedded to a depth of approximately 5 inches below existing grade. The hand cone penetrometer probes indicate the surficial sandy soils around the perimeter of the house and screened porch are very loose to loose to depths up to 42 inches below grade. These data indicate the foundation for the house is locally bearing on very loose to loose sandy soils, which are susceptible to the effects of long -term densification. Given these conditions, some minor differential settlement of the foundation structures and associated minor cracking may occur. The cosmetic distress associated with minor settlements due to long -term densification of supporting sandy soils generally results in hairline stair -step cracks as well as hairline vertical cracks originating from the corners of window openings and the bases of walls. • Rain gutters with downspouts that discharge stormwater near the foundation can result in excessive infiltration concentrated into the near surface sandy soils. This would act to locally densify surficial sands, potentially causing differential settlement of the house and screened porch foundations and erosion of surficial soils along the perimeter walls. • The separation between dissimilar materials and along construction joints are caused by different expansion and contraction rates of the materials related to moisture and temperature fluctuations in the house and atmosphere. Separation between metals and drywall material and wood and drywall are common. The spalling texture along the corner bead of the cabinet soffitt in the kitchen is likewise related to different rates of expansion and contraction of the construction materials. These are not considered settlement related issues. • The cracks observed in exterior concrete garage floor slab are related to drying shrinkage of the concrete mass and relief of generated tensile stress. This condition is not considered a settlement/sinkhole related issue. Subsidence Investigation BCI Project No.: 19 -17094 Barker Residence March 2009 Claim No.: 3428 Page 7