I'm building in Dallas. I interviewed dozens of builders and NONE of them would build without a soil report. In North Texas soils are expansive and a report will tell you the depth of the rock below the clay. The rock depth determines the need and depth for piers and provides info on what type of foundation is best suited.

It is a painful way to spend $1500-2000 but if the foundation isn't right, nothing else will be.

Another place you want to make sure you get "the best in the business" is a surveyor.

We are just outside of Fort Worth and our builder HIGHLY recommended an engineered foundation. He basically told us we would be stupid not to do it. We have really good soil as well, but everyone we talked to in the construction business says it's money well spent. Lonestarstate is right--if the foundation isn't right, nothing else will be. I will also second the comment about getting a good surveyor. We just picked whoever out of the yellow pages and it took him 6 months to survey our land. That's with us calling and hounding him every week to make sure he was making progress. We also got the good advice to spend the money on a good framer.

I would agree with lonestarstate. I live in a different state with similar issues. I first interviewed someone that had a lot of local experience. He reviewed the geological maps of the immediate area with me (free). He was reasonably confident the site was going to be suitable for building.

Once the preliminary plans for the site were done, his geotechnical engineering firm drilled samples to determine the depth to bedrock at key locations. Later, we had no surprises when foundation was done.

Most of this didn't seem like rocket science. If you have expansive soils, dig a hole, and don't hit bedrock by 10' or so, I would think you're going to need a more expensive foundation than you'd like. I realize it's probably much more complicated than this (i.e., different types of bedrock, water,...). Also, you may have to recompact anything you excavate (rather than drill) before building.

In the county I'm building in, a soils test was required before the building department would issue me a building permit. But, I'm building on the front range in Colorado, which has a lot of bentonite in the soil. I ended up having to build a cassion foundation due to the swelling soils present. I don't know what the general soil conditions are in your part of Texas, but I agree with the others in that a soils test is highly recommended before you start building.

I asked my builder months before we were to break ground, should we do a soil test, and he said no, he had been building in this area for long time. The day he broke ground he discovered that we would have to have an engineered foundation (very sandy loam). I still really like and trust this guy, but he was wrong.
My point is that had I insisted, and he listened, we could have planned better. It was not budgeted for though we had built in $$ for cost over runs. It was my entire decorating budget and was the only cost over run on the entire job.

Thank you all for the good advice. I'm just going to have to make room in our budget for it... maybe have to postpone finishing out the "movie room" :)

i live inel paso texas and all of our houses are crumbling because of caleche/ soil is it a must to have a soil sample and core sample in texas?

A soil report may well save you money. In my locale, you either build to what the inspectors minimum, or you get a soil report. Either way, it is cheap insurance to know your investment isn't going to need repairs in the future (engineers tend to be conservative). I know a lawyer that didn't get the soil engineering, it cost hime far more than the soil report to fix his problems within the first five years of ownership, and he thought he would recover this from the builder (I never followed up, maybe he did). Lawyers don't appreciate engineers, engineers don't like lawyers either. Either way, it was an issue that was easy to prevent.

That said, it costs the same amount to form up a foundation regardless of size. I would recommend more cheap insurance is more concrete. Notice what the commercial builders do vs. residential builders; they do this for a reason. Commercial construction is definitely built to a higher standard, a standard that doesn't necessarily cost more.