San Antonio - areas more/less likely to see foundation issues

[Calvin Sam]

Out of state rental property investor here looking for a better understanding of foundation issues in the greater San Antonio area.

Greater San Antonio is fairly large and spread out. Are there parts of the city or zip codes that are (generally) more or less likely to have foundation problems due to the type of soil/clay/stone houses are built on? 

For example, I've read that in Austin houses west of I-35 tend to be built on solid limestone (lower probability of foundation issues, all else equal) while east of I-35 there is more clay soil (higher probability of foundation issues, all else equal). Are there similar rules of thumb for say, San Antonio's NW side vs NE side vs South; inside the 410 loop vs. outside, etc. 

Thank you and happy investing. 

[Seth Teel]

@Calvin Sam 

Foundation issues can occur anywhere in San Antonio, whether it be due to soil conditions or poor building standards.  Homes with pier and beam foundations where generally built pre-1960, homes with slab foundations overlapping some in the late 1940's and 1950's.  This means the majority of the housing stock with pier & beam foundations are located in the urban core (inside 410).  

Pier & Beam foundations almost always require shimming due to some movement, and need to be assessed annually or every couple of years.  Proper skirting, venting, and vapor barriers will minimize movement. Directing water away from the house will also help ensure a longer life.

Slab foundations can see problems as well.  Unfortunately during the tract built boom on the 1980s, 90's and even early 2000's San Antonio saw a lot shoddy work, and homes built with poor construction practices and inferior materials.  As such, many slab foundation homes, no matter their location, can have foundation issues.  That being said, there are areas that are more known for having significant soil and foundation issues.

The Northeast Corridor along I-35 (including Terrell Hills, Windcrest, Live Oak, and further North) tend to have bad soils which can create foundation movement.  Parts of North Central SA and Northwest SA sit atop a limestone shelf that covers the aquifer. Generally speaking these homes have less foundation issues.  You may also encounter sandy unstable soils the further South you go (Elmendorf, Lytle, Dilley, etc.)

Hope this helps answer some of your questions.