Soil types

  1. Is finding bedrock at the very top few feet considered : bad, costly or good for foundations?

  2. Is Clay considered the least stable soil?

1 Like

Hey @heatherrivera, do you have some thoughts on this?

@coachjoshmings @coachdarionziegler @coachzachhoffman @coachjakegroth are any of you available to help us with Mary’s question here in this thread and here?

Hi Mary,

Thanks for reaching out. Hopefully we can direct you to a useful resource.

You may want to check out IBC (2015) Section 1806. This goes into soil types, their pressures, and capacities. Bedrock is the strongest material you’ll find. It’s great to have a foundation or pile rest on it, but you’ll need to check with your geotechnical and structural engineer to make sure the foundation is deep enough and designed in the best way to use the soil conditions. For example, in some areas, a “few feet” may not give you a deep enough foundation if a frost wall is needed.

You’ll also notice in this section that clay has the least stability. This usually has to do with its variable and malleability. Please note that there are many kinds of clay soils (silty, sandy, etc). There are some restrictions for lateral resistance with clay soils.

Keep up with the thorough studies!

1 Like

Hi Mary & all,

Another great resource I’ve found to help understand soils is “Architectural Graphic Standards”. You can purchase the 11th Student addition for relatively cheap (used) and it is a helpful resource for not just testing, but also in practice.

There’s a table on page 4 which is very helpful for understanding soils types and their suitability for foundations. It also has some great graphics and tables showing foundation types! You can also preview some of these pages on Google Books to get an idea of some of the information it contains.