So we are building on a lot in Rockwall. We have soils test which says a soil injection/stabilization is required. Prior to discovering that the foundation costs were about $55,000 with piers. The soil injection cost is $15k with water (100,000 gallons). We are waiting on the builder to tell us if the soil injection completely negates having to do piers or not. Thoughts?

It is the structural engineer's call, not the builders. Builder with 47 years experience building on expansive clays. Use extreme caution.

Yeah that's what I meant. Could a foundation plan go from piers and post tension to just post tension by having the soil injections?

It's my understanding that soil injections prevent expansion upward movement of the foundation. Does it also prevent shrinkage?

Yes, you can change the entire design of the foundation by altering the subsurface conditions.

I would advise you to steer clear of any post tensioned, and get a price to over excavate and bring in engineered fill as well. You may be able to go traditional SOG if it becomes coat effective to modify the subgrade.

Whatever you do - pay a testing agency to monitor and do density tests on subgrade prep! 95% standard proctor, no more than 8" lifts! Pay a little now and do it right, or pay a lot more later to fix it.

I live in Heath and understand how bad the soil is around here. I also work for a large GC and understand the issue.

If I were building new, I would over excavate the slab area by approx 6' and fill with select or flex base. Water injection is a joke. Those guys price it to make one or two passes only regardless of what the lab results show. They always change order you for more.

Good luck. Who is your builder?

We are using Brawner Custom Builders in Canton. Been really happy with them so far. Not sure who they are using for foundation design. I'm just trying to fully understand everything so I can ask the right questions and possibly push back if necessary. I don't have all the info right now to make that decision just yet.

FYI...the soil injections are not just water. It's a chemical as well. Don't have specifics.

Considering building in Heath. What did you end up doing? Piers? Injections? Both?