Saturday, April 17, 2010

Soil and Codes

The city council has soil testing on the agenda next Tuesday. They will decide if soil testing will be the policy for all new subdivisions. This is a needed step in the right direction, but still doesn't completely address the failure at 3008 Clearview. There are still a lot of unanswered questions.

First off, we already had a soil test that said this location had expansive soils which means R403.1.8 of the International Residential Code applies. That sends us to section 1805.8 of the International Building Code. When you get over to Section 1805.8 of the International Building Code list four methods to design foundations for expansive soil. The key word here is “ designed” ie there must be design documents showing that the proposed foundation is suitable for the soil. Documents from someone trained to design foundations as in an engineer.

Bottom line is someone in the city government had to approve the plans for the foundation and that foundation was not suitable for the soil and the area. This should have been caught before the building permit was issued. A foundation designed by a professional engineer should have been required. The proposed policy change is a step in the right direction but needs some fine tuning.

We do have to be careful. We don't want to deal with building codes and related issues in a piecemeal manner. The different codes the city has adopted amount to a few thousand pages that are filled with technical and legal jargon and expansive soil is covered in less than 10. There are lots of potential problems where engineers, architects, and other experts should be involved. The city manager said at the last council meeting “there are things we know and things we don't know”, and that's true but that means they need to get better at doing the research, investigations, reviews, and inspections so they know enough to prevent or at least mitigate problems such as these. The policy should be if in doubt, find out. That's just part of protecting our citizens.

One last point needs to be emphasized: just because a home was properly designed and built for expansive soils doesn't mean there won't be issues in the future. My research has shown that buildings on expansive soil require special attention and handling throughout their life. Simple things like improper lawn watering can shorten the life of a foundation and improper installation and use of irrigation systems, swimming pools, gardens, and guttering can lead to major problems with the foundation and eventual building failure. The city needs to make sure that homeowners know if they are living on expansive soil, and they need to make information available on what to do (and not to do) when dealing with expansive soils.


  1. I have not yet had much to say on this topic. For two years I worked for a local company that did dirt work and housepads, many of them within literal rock-throwing distance of the Montgomery property in question.

    I intend to be careful here. I was an employee, not the manager. I do not represent that I am an expert on dealing with expansive soils building sites. Still, it was a small enough group, everyone did a bit of everything as needed and I did not sleepwalk through my time there.

    Nominally a truck driver, I might find myself setting grade marks, watering fill as it was processed, operating a roller/packer, sometimes all same day, same site. I tried to learn as much as I could trying to increase my value as an employee and not coincidentally, my pay.

    This I can say; it is self-evidently possible to build proper houses on that soil and in that neighborhood because my company did it, repeatedly. Best of my knowledge, no house we prepared the pad for in the few blocks close to 3008 Clearview has suffered the problems so evident there.

    I didn't realize until later, some of the testing we routinely had done was not mandated by the city. Not every contracter built up a pad the way we did. Given the disastrous results at 3008, perhaps such should have been mandated, at least where this soil base exists.

    That last is crucial. There are parts of northeast Angelo where one has only to scrape a few inches deep to hit solid, rock-like caliche. It would be hard to make a foundation there malfunction the way 3008 did if one tried to.

    Clearly, with good houses all around this basket case, somebody dropped the ball, likely more than one somebody. If everyone from city inspections did everything by the book, we need to change the book. I have no personal knowledge of the job at Clearview, but I cannot help but think inspections should have caught a hint somewhere.

  2. Every area of the city has expansive soil. It has been well known for a long time by local builders that post and beam construction set on a vertical wall foundation setting on the caleche (bedrock) is the best design for the local area.

    Slabs always sink and crack, but are cheaper. I have renovated houses out as far as Rowena where the floor in the middle of the house has risen a foot and the walls have sunk the same.

    There are $500,000 houses on these ten acre lots ($8,000 per acre for the land) in the gated community east of loop 306 are having similar problems. Owners and real estate agents freak out when these problems are brought up by local contractors who repair ceramic tiles and cracked sheet rock in this area.

    The amusing thing about these ½ million dollar houses is that they are huge but the interior is empty with small bedrooms build around the second exterior wall and a “large” living room with a “high” ceiling, small kitchens and a small den/slash office.