If your facility experiences issues with walls or foundations bulging, sagging, or settling, you’ll need to rectify the problem immediately. This post unpacks how to inspect the extent of this issue using a plumb line and measuring tape.
The Power of 3D Scanning
Although there are old-fashioned ways of monitoring changes in structures, 3D scanning is revolutionizing this process. For situations like building inspections or deformation analysis of high-volume tanks, 3D scanning will give you far more data to make informed decisions. Building stakeholders or property managers can use 3D scanning to see settling or different deformations, including bulging, sagging, and settling. You can even track the entire structure over time and see how it is changes in circumstances like full versus empty or winter season versus summer season. 3D scanning empowers you to see the complete picture and ensure the integrity of your structures.
How to Measure Facility Issues like Bulging, Sagging, and Settling?
We’ll describe how to identify and assess various types of foundation/structural damage or failure. Cracks, bulging, sagging, and settling are all common issues, and most are easy to locate and evaluate with the right strategy.
5 Easy Steps to Measure Bulging, Sagging, & Settling
Step #1 – Draw a Plumb Line
A plumbline is a retractable string suspended by a weight on one end of the line. This simple tool allows the user to compare a foundational wall surface to a perfectly straight vertical line. Drive a nail into a subfloor overhead or floor joist in the ceiling.
Use your observation to assess the portion of the foundation wall leaning or bulging the most. Place the nail less than a foot away from this wall section to suspend the plumb line. Stop the plumb line movement, settling it into a steady position.
Step #2 – Use a Tape Measure
A ruler or yardstick is ideal for measuring the distance from the vertical plumb line to the wall. Measure at several locations along the wall, going from the top to the bottom of the plumb line in each place. Make a pencil marking on the wall noting the measurement, or write it in a book for reference.
Step #3 – Subtract the Measurements from the “Home Base” Measurement
Usually, you’ll find the bottom of the wall has minimal movement. Compare the difference between the measurements you collected. You’re interested in seeing the difference in measurements, not the absolute value of the measurements.
The bottom of the wall provides the base reference point for measurements. Typically, the bottom of the wall will not move inwards, especially if the initial construction involves pouring a concrete floor against the foundation.
The floor slab acts as an anchor, holding the bottom of the foundational wall in position. Take the distance from the plumb line to the bottom of the wall and use it as your base point for zero movements.
Step #4 – Compare the Measurement Values with the Wall and Plumb Line
If any part of the foundational wall is higher than the floor level due to sagging, bulging, or settling, the measurements from the plumb line to the wall are less than the distance measured above the floor level. This indicates a movement of the wall inwards toward the plumb line.
Step #5 – Compare the Measurements to Recommended Measurement Values
Compare your measurements to assess whether repair or further analysis is required. Unfortunately, there’s no national building code standard on these numbers due to the need for assessment of site conditions. For instance, a minimal amount of new movement in an old foundational wall might be significant.
A Practical Example of Measuring Bulging, Sagging, and Settling
- Eyeball the bulge, sagging, or settling in the foundational wall and estimate where it moved the most. Typically, the movement is greatest at the center of the wall in a right-to-left dimensional setting. Hang the plumb line from the closet floor joist and keep the line four inches from the foundation wall.
- Start your measurement one inch above the concrete floor, using it as the exercise’s home base or zero point.
- Measure two inches from the wall surface to the vertical string at five feet from the zero point.
- Measure 3 1/4 inches from the same wall surface to the vertically hanging plumb line at the top point of the foundation wall, under the sill plate.
- Check that you measure the wall area presenting the biggest bulge or sagging point. To do this, move the plumb line left, then right on each side of the joist used to hang the plumb line during the initial measurement.
- Suppose the wall-to-string differences in your measurements are greater than those measured in the initial measurement. In that case, that measurement is the point showing the most significant inward bulge of the foundation wall.
- Finish by doing the math on the exercise. Subtract the measurements from higher on the foundation wall and the measurement closer to the string from the measurements at the floor and farthest from the plumb line.
In the webinar video below, you’ll see exactly how 3D scanning can help you get the precise information you need to ensure your buildings or structures are accurately assessed, monitored, and maintained with utmost precision.
Precision Surveying & Consulting
3D Laser Scanning | Land Surveying | Ground Penetrating Radar (GPR)
Established in 1999, we operate nationwide with vast experience in a diverse range of services. Our products and services are suitable for Industrial, Medical, Data Centers, and Commercial Sites. We employ highly skilled and experienced professionals and a licensed surveyor, licensed in the state of Nebraska, allowing us to process and certify all our data in-house. The security and confidentiality of our client’s data are paramount to our working practices. We bring extensive experience and professionalism to every project and customize our support to your individual needs and concerns.
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