In our previous discussion, we covered basic patterns in topo elevations and other important data that can help identify foundation heave or settlement. I mentioned that, since the elevations are only relative to each other (with benchmarks difficult to come by), more data is needed to arrive at robust conclusions. 

So now, I want to suggest one important rule:

Never look at topo data without examining it with signs of stress and other important data.

This may seem obvious, but it’s a common mistake in the foundation repair analysis industry, especially by those who are less trained and informed.

Sometimes, Data Fits Together Nicely

In re-examining the topo on the left, the diagonal crack in the floor and the cracks bordering the low area in the walls help point us to the conclusion of settlement in that area. These were two of the most important corroborating data. 

Meanwhile, on the right, the crack running down the middle of the floor and the other interior damage and a lack of perimeter wall damage and similar perimeter elevations all point to a classic dome heave, along with other corroborating data. 

Sometimes, the Data Makes You Scratch Your Head

In some cases, the topo patterns are not so obvious and require more thought and data to reach supportable conclusions. Take the example below:

One side is high, and the other side is low. Has the high side heaved? Or has the low side settled? Or both? 

This issue is quite common, and it requires us to carefully consider the other guiding principles mentioned earlier. In the above example, there is significant damage in the walls of the lower readings that indicate footing settlement. This is where foundation repair analysis becomes crucial, to discern the underlying causes accurately.

Other Things You Should Consider in Foundation Repair Analysis

• Are there floor cracks in the high area (just like in the example above?) This can indicate heave of the floor slab. 
• Are the baseboards crammed in the high areas? Cramming is usually a good indicator of floor heave pushing up on the baseboard.
• What are the local historical soil types? (clay or sands?) No clays… no heave.
• What is the historical climate condition? (wet or dry?) Drier climates usually indicate more likelihood of heave. 
• What side is exposed to the sun? Sun facing sides are more prone to drying clays and resulting settlement, while north exposures are more prone to heave since the clays don’t dry as easily. Here’s how to find it out using aerial photography. 
• Which way does the drainage flow around the house? If water runs to the low side, it points to settlement. Alternatively, if it flows to the high side, it could point more toward heave in that area. 
• Are there trees and/or grass on portions of the home? Tree roots steel moisture. Grass is usually overwatered and contributes to heave.
• Is there a pool on one side that contributes to poorly draining Deco Drains? Are there other important drainage conditions?
• What is the foundation type? Crawl spaces are less likely to heave. PT foundations are more likely to heave. 
• How old is the home? It takes time for moisture to accumulate near the middle. 
• What is the history? Has the plumbing been checked by a leak detector (not a plumber) Have repairs been done? (More info about this soon!)
• Was there a cut or fill anywhere on the pad for the home? Cut may indicate the likelihood of heave, and fill is more likely to indicate settlement. (see below)

Reconsidering Previous Conclusions

Sometimes, data can lead to different conclusions depending on how it is gathered. 

This reinforces my overarching point. There is rarely a single smoking gun that can definitely point to a conclusion. 

It’s important to consider all the points and weigh them against each other to see how they stack up. Then, revisit the conclusions we’ve reached based on each point to see if there are other possible conclusions that could also be supported. I have seen each one of these rules of thumb lead to completely different conclusions in unusual circumstances.

For example, (see above): I once worked on a home that had a settlement on the cut side. 

The builder, in this case, over-excavated the cut and filled it back up, improperly leaving it unconsolidated and susceptible to settlement. This is opposite to normal expectations, as noted above. I have also seen fill-over compacted with clayey soils that resulted in heave when wetted. Again, this is the opposite of normal expectations. 

Another example: Could the exterior door damage be from the footing settlement? You can check out this blog for more info.

Or from the floor slab, should the pour-out notch be pushed up on the door frame? How strong is the evidence in each point supported? Could it be subject to unusual conditions?

Re-examining a prima facie conclusion can often be the most difficult part. This involves reviewing previous conclusions about data to see if they align better with the rest of the data. Foundation repair analysis requires careful consideration of all factors to avoid errors due to cognitive heuristics and biases.

Human cognitive heuristics and biases can make this challenging, including biases like confirmation bias. I will go into these in more detail at another time. But, one way to address these biases is to seek input from peer review. Other professionals may not be subject to the same heuristic limitations and can offer alternative points of view, which can open up new thought processes and help us reach better, more supportable conclusions.

A Case Study in Challenging Initial Conclusions

I have witnessed respected forensic experts sticking to their initial conclusions, even when presented with contradicting data. In one instance, a respected engineer conducted soil borings on a house and concluded that the differences in floor elevations required pressure grouting of the slab on the perimeter. My concern was that this could lead to further damage, as the baseboards were already under pressure from the soil pushing the slab up. The engineer was confident that there was no center heave because no clays were found in his drilling. 

However, I pointed out significant elevation differences in the ground based on the location of his boring, near the street in front and the home, which was about 20 feet lower in elevation. I knew that there were known clays in the area. To his credit, he revisited the site and drilled in the backyard at elevations closer to the home and found expansive clays.

This example highlights the value of thorough foundation repair analysis.

Key Takeaway: Foundation Repair Analysis

I believe this example illustrates the amount of consideration, effort, and thought processes needed to reach a well-supported, strong conclusion. It shows that this type of work cannot be done hastily, and it can be very challenging for most salespeople. 

We haven’t even addressed the monitoring process, which involves looking at all of these data points over time and is often the only way to make solid recommendations. It may even require borings sometimes. 

My point is that this kind of work is for serious forensic experts, not for halfhearted investigations with just pretty pictures. A proper foundation repair analysis demands precision, expertise, and a comprehensive view of all influencing factors.