South of Waco? How deep & how much cover.
This would not be under house
Would be storing home canned goods, taters, fresh eggs & whatever else
Will survive

East or west of 35?

Ground is pretty hard and rocky here -- I've live north and south of Austin and no one around here has cellars or basements.

30 miles east near state park: just wondering what
Kind of temps to expect- got a book on building them, just wondering
About others results

You might get lucky and be able to dig 8ft. It just depends on your location. My parents house is closer to Dallas and my Dad wanted a concrete storm shelter.

He used his backhoe and hit rock at 3ft. The storm shelter installer had a bigger backhoe and got him down another foot.

So the shelter is 6” concrete, half in/half out of the ground and has dirt mounded around it and partially covers the top. Stay pretty cool in the summer. My Dad loves to go down there and take naps during storms.

I actually have a small basement in a small commercial building in Dallas built in the 1920’s. Temps stay nice down there too, but all my employees say it’s haunted

In the caves in the hill country, you have to go down about 20’ before it starts to cool off. If you are on lime stone, good luck.  If you are on river bottom east of IH-35 you will hit rock hard clay.

Maybe if you get lucky & find a cave entrance on your property.

It's hell on wheels everytime so much as a swimming pool is trenched in the north Austin area up on the cap rock; they have like 18" of soil there before solid limestone as far down as you can drill.  It's why the whole region is dotted with limestone quarries.