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Understanding Your Engineering Report
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At first glance, an engineering report can be very overwhelming and confusing. These reports are usually at least 50-60 pages long and are full of technical jargon. You don’t need to feel intimidated. To find out if there are possible sinkhole conditions at your home or business, read these two sections of the engineering report – the Floor Elevation Survey and the Standard Penetration Test (SPT) logs.
The Floor Elevation Survey
The Floor elevation survey is important because sometimes sinkhole activity will cause the foundation of a home to sink. The floor elevation survey assists in identifying height differences in the foundation. Look out for height differences of 1.5″ or more. Damage usually appears in areas where there is a tilt in the foundation.
The Standard Penetration Test (SPT)
The other most important part of the engineering report to examine is called the SPT (Standard Penetration Test) logs.
- The left side of an SPT log displays the depth, (in 5 foot intervals), into the ground.
- On the right of the depth chart is a series of numbers, that include the “N-Value.” Pay attention to low N-Value numbers after the first 5 to 10 feet of depth.
- Any N-Value numbers less than 15 should be carefully considered especially if they are N-Values indicated as WOH, WH, WOR, and WR. These abbreviations mean that the N-Value is ZERO.
- A zero N-Value, such as a Weight of Rod (WOR) or Weight of Hammer (WOH), may mean that there is a void or a sinkhole.
