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Discussion Starter · #1 ·
Hello everyone, I'm new here.

I will be starting a new home build soon and doing most of the work myself. Of course I want to leave the foundation to the pros.

I am ready to start looking for a contractor to pour my foundation soon. I would like advice on what to ask as my situation may have some challenges. I just want to be prepared while speaking to concrete contractors.

The terrain where the house will be has a slope of about 2 to 4 degrees. I believe Erosion has pretty much washed away most topsoil and rock hard caliche (clay) is at the surface. I was told by neighbors that the caliche was about 8 inches to a foot thick.

About three years ago I leveled off a approximately 42' by 62' area to build on by hauling in several more loads of clay. Over the 40 foot width the front was raised about 7 inches and the back was raised a little more than 2 feet to level it off. In the three years the clay has packed and settled very nicely.

I live in Texas so freeze thaw is not an issue. Foundations are usually dug to about 18 inches here, sometimes less.

How deep should they break into the caliche to set the foundation? 2 1/2 foot all the way around?
Would footers at the corners into the clay do the trick?
Would fastening the foundation to the clay with rebar be enough?
Am I worried too much about a slope of 2-4 degrees?

I'd prefer my house does not come sliding down the hill. Any advice? Pitfalls to watch out for? What would you do?
 

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Civil Engineer
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You need a foundation design prepared by a local professional, with expertise and liability insurance, so that if there are any problems you will have recourse. You are talking about a 2400 square foot house footprint, which is a pretty good size. Your local professional will understand what works in your area, what building code requires, and what should work best on your site. Local contractors may have someone they work with in the area to design the foundation, in my experience the contractor often does not design the foundation, they have an engineer or architect they work with do the design.
 

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I agree 100%, local pros would be best instead of well meaning guesses on the net.
There's been a lot of post on this and any DIY site about the shrink swell soils in TX from clay causing foundation issues.
The rest of the US is trying to keep moisture away from the foundation, in some parts of TX there adding water lines to add moisture.
 

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Discussion Starter · #5 ·
Thank you for the advice everyone. I already have the plans drawn up for the house. Of course that did not take into account the soil.

What kind of pro should I look to hire?
Any way to give me a ballpark figure for cost so I can budget it in and not get ripped off while I am searching for someone.
 

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That type of soil can be very tricky to deal with since you have both natural deposits and relatively weak disturbed soils. It reacts with moisture, but the moisture does not get to all of the soil at all times. It does not flow through the natural bedding and you may not have the same moisture content in all of the soil and differential expansion or settlement ca be very possible.

Contact a geotech engineer or an engineer that is very familiar with the local material and there. Not all similar looking materials act the same.

Dick
 

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Concrete & Masonry
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3,970 Posts
If unsure, get a soil guy, follow the IRC. But most important use ICFs.

You must sell ICF's or something, as there's zero benefit from using them in Texas.......


Thank you for the advice everyone. I already have the plans drawn up for the house. Of course that did not take into account the soil.

What kind of pro should I look to hire?
Any way to give me a ballpark figure for cost so I can budget it in and not get ripped off while I am searching for someone.

Geotechnical engineer or soil engineer. It might be easier to search for a structural engineer that specializes in this field, or can offer a refferal.....
 

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You use ICF's on slab on grade construction?? Why?
Why do you say slab on grade construction? The majority of the home with I was around in SC were built on top of a crawlspace. Besides, ICFs advantages are still demonstrated even in the case of slab on grade construction. You can the additional strength as well as insulating qualities no matter what type of foundation you are building on.
 

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Concrete & Masonry
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The OP is in Texas, and mentions an 18" foundation depth. To me, that elludes to a slab on grade, most likely grade beams or post tensioned.

I've never seen anything but stem walls, or two-sides forming, done with ICF's. If insulation is needed on the perimeter, there's far more efficient ways to accomplish that than ICF's.........
 
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