New Braunfels Foundation Experts puts homeowners and property owners looking at drilled bell-bottom piers in New Braunfels, TX in touch with an independent local foundation company that builds them.
Picture a drilled hole filled with steel-reinforced concrete, flared wider at the bottom like a bell. That is a bell-bottom pier. The bell spreads the load across more soil and resists upward movement when expansive clay swells, which is why engineers often specify drilled piers in Texas clay.
Construction
- A shaft is drilled beside or beneath the foundation beam.
- A belling tool cuts the flared base at the bottom.
- Reinforcing steel is set and the shaft is filled with concrete.
- The concrete cures before carrying load.
- The foundation is lifted on the piers and shimmed.
Drilling in New Braunfels Ground
Drilling conditions vary across the city. In deep clay on the prairie side, shafts can be drilled and belled in soil. Where limestone is close to the surface, drilling may hit rock, and the design may change. An engineer can account for both, which is one reason drilled piers are usually part of an engineered plan.
Where They Are Used
- Engineered repairs for larger homes
- Commercial and multifamily buildings
- Sites where uplift from swelling clay is a concern
What to Plan For
- Time: curing adds days to the schedule.
- Access: drilling rigs need room on the lot.
- Cost: usually more per pier than pressed concrete.
- Spoil: drilled soil and rock must be hauled or spread.
Questions to Ask
- Shaft diameter, depth and bell size?
- Who designed it, and will I get the drawings?
- How will the shafts be inspected before the pour?
- How long will the concrete cure?
- How will the rig reach the work area on a sloped lot?
When the Drill Hits Rock
West of the Balcones Fault, limestone can sit close to the surface. A drilled pier that reaches rock sooner than planned may need a different depth, bell or design, and that is a call for the engineer, not the drill operator. Ask before the job who decides what happens if a shaft hits rock early, and whether a change in design changes the price.
On the Day
A rig drills each shaft beside the foundation beam, a tool widens the bottom into a bell, and the crew sets reinforcing steel and pours concrete. The house is lifted only after the concrete has had time to cure. Until then the yard holds equipment and piles of soil, so plan around pets and irrigation.
What to Keep
Ask for a drawing showing every pier with its depth, the date of the pour and the before-and-after level readings. File them with the warranty.
Ask too how long the crew expects the concrete to cure before lifting. Write the answer on the contract.
Common questions
Why do drilled piers take longer?
The concrete must cure before it can carry the house.
Can bell-bottom piers be drilled into rock?
Drilling can reach rock, but the design changes. An engineer decides how piers should bear on it.
Are they worth the cost?
For some houses and sites, especially engineered ones, yes. Ask why they are recommended for yours.
Can they be installed inside the house?
It is possible but harder. Many plans use drilled piers outside and another method inside.
How much do they cost?
Usually more per pier than pressed concrete. Angi lists piers in general at about $1,000 to $3,000 each.
Do I get the engineering drawings?
You should. Keep them with your warranty and records.