Residential Foundation Recommendation 1

[hightechgolfer]

I am currently a CIVE E.I.T. with work experience in the retail commercial sector. I am about to start building my new residence. I am having a really hard time trying to decide the type of foundation to put under my residence.

My lot is in Montgomery County, Texas, which is north of Houston. The lot has silty clay with a mixture of iron ore in the first few feet of the soil. The lot will be cleared sometime in the next week so that the geotechnical engineer can make the borings and get a report to me with more specifics of the subgrade.

My home is pretty much U-shape with a total slab area of 3,483 sf. The bottom of the U is two-story.

Thank you in advance for any comments.

I would like any ideas on whether to use a post tension slab, slab-on-grade with grade beams and piers or any other suggestions.

 

[ctmtwilliams]

Is there some reason you don't want to wait for the Geotech report to see what you may need to design for?

The report will give you the minimum parameters you'll need to design to. It will then be up to you to choose the most economical and practical foundation for the type of building you want to build. The report could keep you from over-engineering your foundation.

 

[hightechgolfer]

I have already talk to the geotechnical engineer, which has performed studies within the same development as my lot. His preliminary answer was that I would have the option to do either of the foundations. After reading some materials, it seems to me that the arguemnt of PT slab vs. conventional slab is a pretty heated one. I would just like to select the best option.

 

[BigH]

Be careful - from what I understand, there are some tricky areas in TX. If you do a search on expansive soils, you will find a couple of references to a Texas Residential Foundation Manual (not sure of the exact name unless I do a search of my hard disk). This is a topic of importance in Texas I understand. Might want to check out some of the past threads in the site; there has been a number of other ones on PT foundations in Texas (search for Focht3's comments).

 

[UcfSE]

Maybe you should consult a licensed structural engineer experienced in the area in which you want to build. He or she will know whether you typically have expansive soil problems and will have some good input about what type of slab and support to use. There may be things you consider you don't know about, such as the quality of contractors for a given construction type in your area and the cost of each.

 

[Focht3]

Forget the square U shape unless you are prepared to live with cracks/distortion at the corners. Stick with a reasonably square shape - you will have far fewer problems that way.

The soils get better as you move north of Buffalo Bayou - so yours should be pretty good. SHOULD. But you also need to be aware of growth faults, particularly from salt domes...

Contract with a qualified local geotechnical firm to consult with you. It's money well spent. I'd suggest Marie Starich with Solum(?) Engineering in Missouri City or Zeki Tolunay with Tolunay-Wong in west Houston. DON'T GO CHEAP WITH YOUR CONSULTANT.



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See faq158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"

 

[hightechgolfer]

Focht3,

Thanks for your response. With regard to the shape of the house, my wife is dead set on this house. So I have to find a way to overcome the problems that come with that shape.

Cracks/distortion at the corners: This has been a concern that I have thought about. Other than reinforcing the corners, are there any other ways to combat cracks? And are the cracks more prevalent in conventional slabs or PT slabs?