×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Sog with drilled piers

Sog with drilled piers

Sog with drilled piers

(OP)
Hey there
I am in Colorado and we have highly expansive soils and into most case we drill piers or over excavated for foundations. I have a home builder who agrees that piers are best but wants a sog instead of structural floor. And instead of native clay soil under the slab use a base or sand. My foundation over ex for footing and sog was over ex 7’ below footing and replace with A-2-4 or better. And to over ex and remove the native and import is to expensive. Other than mixing like 80% import with 20% is the only thing I can think of to cut cost.

RE: Sog with drilled piers

Which is more expensive? Doing it right now, or doing it wrong now and fixing it later? (It's the second one every time.) That is a lot of excavation and fill...but with a proper pier layout, void forms, and rebar, a structural slab won't be too bad.

I've only been in business for myself for a short time, but I've already learned that the clients that try to cut costs on the really important stuff are the kind to avoid...partly because they tend to try to cut my costs, too, but mostly because their risky behavior isn't worth it. If you force the contractor to do it right (or, at least, don't give him permission to do it wrong), you may lose the client...or you may not. If you do, probably a good thing, if not...then they know where you stand on dealing with expansive soils.

RE: Sog with drilled piers

Can you clarify what you're proposing. Are you using piers or footings with the overexcavation? Will there be a basement level. How expansive are the soils in the upper 30' from finished grade? Can you give a general subsurface profile?

RE: Sog with drilled piers

How thick would the sand be, and what are it's gradation and permeability characteristics relative to the surrounding soil?

Careful that you don't build a shallow bathtub under the house to draw water into that will sit on top of the underlying expansive clay and ruin the house.

RE: Sog with drilled piers

If you use piers to prevent uplift, expect the sog to lift. That's likely why industry practice is to use structural floors to avoid the movement to come. If you over-excavate and rebuild with non to low expansive fill, then use shallow spread foundations with the sog.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close