Most homes in Texas don’t have basements. The water table and the soil prevent it.
 
A “Texas basement” is an attic.
   
 
International Real Estate Digest: USA/Texas
Why don’t Texas homes have basements? The water table is too high (i.e., the earth’s crust, or soil depth, is too thin, often only a few feet thick).

A “Texas Basement” is an attic area, often accessible though a closet or hallway on the second level of a home. More often, Texans’ use a portion of the garage for storage. Mechanical equipment is usually small enough to fit in a closet since most heating is either natural gas or electric….no boilers or oil tanks are necessary.
 
Google Groups: rec.models.railroad
From:  GP40X
Date:  Sun, Dec 21 1997 12:00 am

I put the question to Bob & here is his answer.  I have also posted my private response to him to clarify my home design.  Luckily I have a single level home with no basement.  I am using a “Texas Basement” i.e enclosed garage for my layout.
 
Google Groups: alt.tv.x-files
From:  Sarah E. Aalderink
Date:  Sat, Jun 20 1998 12:00 am
 
The houses and the wooden fences are *very typical of the whole Dallas area… and the fact that the houses are so close together. However, the ‘desert’ area behind the houses, where the kids were
digging/playing is not at all typical of the Dallas area, from what I’ve seen. The earth there is *clay, not sand. My new house is in Plano, almost to the boarder with Frisco?...Fresno? Oh shoot, can’t
find my map of Dallas. I wanted a basement, I’m from Michigan, of course I want a basement. But the costs of digging in that clay are *very prohibitive. So I’ll settle for a Texas basement… the huge
attic that every house seems to have.

Google Groups: rec.food.cooking
From:  Curly Sue
Date:  Sun, Jul 13 2003 5:39 pm

>Very few houses in TX have basements, for a variety of reasons.
> There’s a lot of limestone in our area, for instance, which makes it
>really difficult to dig a basement.

http://tinyurl.com/gtgt

>In other areas of the country, flex space is standard in garage areas,
> especially if a third bay in a garage is involved. In Texas, where houses
>are built on concrete slabs, that flex space is referred to as a “Texas basement.”