When evaluating property, it is absolutely critical to have an error free onsite foundation inspection process. But the supplemental research and data that is gathered off site is just as important. This data allows structural or foundation engineers and engineer-trained technicians to see the full picture. Below I’ll cover these foundation inspection details and why they are integral to a good outcome. 

The Foundation Inspection Details Are Reviewed By Engineers

In my last blog I covered the process of onsite foundation inspections . We created this process at my former company, Arizona Foundation Solutions. We did this to endure the communication, and robustness of mutual expectations between engineer and onsite tech. These foundation inspection details left our engineers feeling confident enough to not visit the property in person.

This is important, because if an engineer feels they do not need to visit the site, they can produce a quality report at a competitive price. This translates to good profits and minimal risk for the engineer. Meaning they can advertise and compete with foundation repair companies.

Data is Received in Real Time

It is critical for the engineer to receive the data as it is collected in real time. This allows them, if needed, to ask for clarification while the tech is still on the site. The engineer receives these foundation inspection details and data via the cloud, which is then formatted to build a report.

This software can then be programmed to automatically gather additional information from public sources, such as:

• Soil information
• Annual precipitation
• Aerial photography
• Historical aerial photography 

Other Foundation Inspection Details Engineers Gather Offsite

Did you know?  Soil data that can be used to add to the foundation inspection details is available online from the National Conservation Research Service (NCRS). This is usually displayed as a map as shown below.

Specific, local addresses can be searched to gather more precise data. However, there are limitations to that data. For instance, it only contains information on the upper five feet of soil at the time of collection. This means that if the developer or builder disturbs those soils with cuts or fills, the data will no longer be accurate.

When the Data is Limited, Seek Other Sources

Because this data is for soil characterization only, it does not provide details such as:

• soil densities
• consolidations
• other similar data

Yet, you might be able to see if the upper soils have a potential to heave if the soil is relatively undisturbed. Settlement is not so easily predicted in the upper five feet of soil, however. This is because many times the deeper soil is responsible for settlement. 

Couple all of this with the lack of site specific data as a comparison, and we can start to see the limitations of this data. 

Fortunately, there are additional soil data sites, containing information such as well drilling data, that may be available in county records. It’s also possible to find other publicly available soil data.

Of course if a site technician can document desiccation cracks of the surface soil, or can document heaving of exterior surface paving onsite, that helps greatly.

Annual Precipitation Must Also Be Considered

Documented annual precipitation data from nearby public sources is important as well. This data helps characterize whether the soil is wetter or drier on a long term basis. These are  important foundation inspection details to understand and analyze. Why? Because after the home is built, the likelihood of heave due to moisture accumulation from poor drainage can increase more than in a home built on wet soils. 

Conversely, homes built on wetter soils may have less accumulation under the foundation, and therefore have a greater propensity to dry out around the edges.

 Of course, site topography must be documented by the site technician as well. This allows them to discover any natural accumulations from rain surface flows. This can be supplemented with Google Earth Elevations.

The map below correlates fairly well with the Thornthwaite Index.

Aerial Photography Adds to the Foundation Inspection Details

Aerial photography is immensely helpful. Even Google Maps or Earth images can shed important light.

They can reveal important details, such as:

• Areas of limited drainage with small side yards
• Grassy areas that tend to be overwatered
• Trees that can pull water with their roots, or sometimes identify root uplift

The engineer can also request that the site technician check deco drains from pools for positive drainage, though usually there are not any.

Even small factors form the whole of the foundation inspection details. For instance, which area a roof pitch drains.

Looking to the Past to Understand Future Possibilities

It’s not just current aerial photography that can help form the foundation inspection details.   Historical aerial photography helps shed light on unusual conditions. For instance, sometimes arroyos or natural drainage may have traversed the site prior to development. 

These historical aerial photos can also reveal elevation differences that may point to the site being filled during development. WIthout this data, the area would not be described or known as a fill site, though this evidence shows it to be so now. 

In fact, one time we discovered that a particular site sat on top of the burial pit for the original farmer’s animals!

This is why engineers and technicians should always keep their eyes peeled for more public data that can help characterize the site more accurately. This attention to these types of foundation inspection details solves head-scratcher conundrums that occur from time to time and minimize having to return to the site to gather more data. This all equals time and money saved.   

The next blog in this series will cover what to do with all the data accumulated and how to arrive at likely causes of distress, form conclusions, make recommendations, and build repair plans and specifications.