Under-slab tunneling & access excavation · San Antonio & Austin
Under-Slab Tunneling in San Antonio
Under-slab tunneling is how you reach a sewer line, slab leak, or interior pier beneath a San Antonio home without breaking the finished floor. We hand-dig the access from outside, shore it to OSHA practice, and back-fill it in compacted lifts; your licensed trade does the repair. Serving San Antonio, Austin, and the I-35 corridor.
The cleanest way to reach what's under a slab
Under-slab tunneling and access excavation for plumbing, foundation, and structural repairs.
When a sewer line, a slab leak, an interior pier, or an engineer's evaluation sits under a concrete slab, there are two ways in: break the finished floor from inside, or tunnel under it from outside. Tunneling keeps the floors whole, lets the household or business stay put, and avoids the concrete-and-flooring restoration that interior breakout always brings. It's the approach that makes sense on most finished homes and occupied buildings across Central Texas.
Motmot sells the access, not the licensed pipe work. We come out of foundation repair, so we know how a line runs under a Central Texas slab, how deep an interior pier needs to go, and how much room a plumber needs to actually work. That's why our tunnels are something a crew can work in, not just a hole in the ground.
What we dig
Five under-slab tunneling services.
Plumbing tunnel excavation
Access tunnels and trenches so a licensed plumber can replace a sewer line, drain line, water line, or cast iron under your slab, without jackhammering your floors.
Learn more →02Foundation repair tunneling
Interior pier access and engineer-access tunnels so piers go in and plumbing is protected, without breaking the slab from inside the house.
Learn more →03Engineer access tunnels
Clean, shored access so a structural engineer can observe grade beams, plumbing penetrations, voids, moisture, and soil under the slab.
Learn more →04Commercial under-slab access
Low-disruption tunneling under restaurants, clinics, schools, and retail so business keeps running while plumbing or structural work happens below.
Learn more →05Tunnel backfill & cleanup
After the repair: backfill placed and compacted in lifts, the site restored, spoil hauled, and the work documented. It's the part a lot of diggers skip.
Learn more →Why a foundation crew digs a better tunnel
We come out of foundation repair, and we've dug alongside plumbers for years, so we know how to dig it.
We know how a sewer line runs under a slab, where the belly usually hides, and how much room it takes to set a fitting and lie down to make a joint. So we open the bore wider at the repair, shore it, keep it dry, light it, and get out of the way. Years of watching the pipe work happen is what tells us how wide to make it.
- We open the work area wider where the repair is, leaving room to set, slope, and joint
- Shored, dry, and lit so the plumber works in a tunnel, not a hole
- We dig it and back-fill it; your licensed plumber does the pipe work
How every bore is held
Velocity, precision, OSHA, quality control, and the standards behind them.
Tunneling is the slow, risky part of a plumbing or foundation job. We run it like a discipline, not a dig.
Velocity
Hand-tunneling is the slow part of any plumbing or foundation job. We staff the bore to the schedule and hand over an open, ready trench instead of billable hours spent waiting on a shovel.
Precision
We dig to the plan. Depth, width and pitch are shot before the first spade and verified as we go, so the pipe run or the pier lands where the drawing says.
OSHA safety
Cave-in exposure is real. We work to OSHA Subpart P excavation practice: protective systems, safe access and egress, spoil set back from the edge, water and air managed, and daily competent-person inspection.
Quality control
Every bore is checked against the drawing for working width, clean floor and walls, and true pitch. Backfill goes in compacted lifts so the ground above settles right.
Standards & compliance
Texas 811 is called and lines are located before we dig. We sell the access, not the licensed pipe work. Permits, locates and clean documentation come standard.
Who orders the dig
Who Hires Us for Tunneling
Most tunnels get ordered by a pro who needs the ground opened for their own trade. Here is who calls, and what each one needs.
Foundation repair crews
When the elevation survey calls for interior piers, we tunnel to the marked locations at pier depth so support goes in from below and the floors stay whole. The plumbing is protected during the lift, and the same shop digs the access and sets the piers. When the survey says hold rather than raise, the same access serves fixing a foundation without lifting the house.
Structural engineers
An engineer can't certify what they can't see. We dig to your entry, reach, and exposure spec, shore it, and photograph the opened conditions before backfill closes them. More on foundation repair for structural engineers.
General contractors & remodelers
A relocated bathroom or a new laundry drain needs a path your plumber can rough in through. We dig to the fixture plan on the date the schedule needs, then backfill in compacted lifts so the slab patch sits solid. More on foundation repair for general contractors.
Property managers & multifamily
An interior breakout in a leased unit costs lost rent, a relocation, and flooring you buy twice. Tunneling from outside keeps the resident in place, and cast-iron access can be staged building by building. See foundation repair for property managers.
Commercial operators
For a restaurant, clinic, or school, closed doors cost more than the dig. We phase the access around operating hours, keep entries off the customer path, and compact the backfill so slabs and drives settle right. The structural side lives on commercial foundation repair.
Real estate investors
A flip needs a number you can underwrite and a date that protects the close. We scope the access as one line, shoring and restoration included, and leave the property sale-ready. The repair side is on foundation repair for investors.
Realtors & inspectors
The dig is the slow half of a pre-closing repair, so call the day the issue surfaces. We photograph the access, the condition under the slab, and the finished backfill so the buyer sees a documented repair at the table. More on foundation repair for realtors.
Restoration contractors
Behind many water-damage jobs is a leak under the slab nobody has reached. We tunnel to the source, photograph the cause of loss while the access is open, and backfill to a subgrade reconstruction can sit on. Trade lanes stay clean, as on foundation repair for restoration companies.
From locate to backfill
How an under-slab tunnel runs.
Locate & plan
We call Texas 811, locate utilities, and shoot the depth, width, and pitch the repair needs before a spade hits the ground.
Open the entry
A compact entry pit goes in at the chosen point, usually outside the foundation, so the floors above stay whole.
Tunnel to the work
We hand-tunnel to the pipe run, pier location, or access point, widening the bore where the repair happens.
Shore & hand off
The bore is shored and inspected, then handed off open, dry, and workable to your licensed plumber, foundation crew, or engineer.
Backfill in lifts
Once the repair passes, we place backfill in compacted lifts so the slab, drive, or walk above settles correctly.
Clean & document
Spoil hauled, site restored, and the access and backfill documented for your file or warranty.
LICENSING & SAFE DIGGING
In Texas, plumbing repairs are regulated by the Texas State Board of Plumbing Examiners, which issues Tradesman, Journeyman, Master, and Inspector licenses. Motmot sells under-slab tunneling and access excavation, and partners with your licensed plumber for the pipe repair. Before any dig, Texas 811 is contacted at least two business days ahead so gas, water, and utility lines are located first.
Tunneling FAQ
Under-slab tunneling questions, answered straight.
From real jobs
Under-slab access, dug and documented.
Tunnels, access pits, exposed pipe and piers, and clean backfill, all from real Central Texas jobs.
Financing through Acorn Finance, an independent third party. Checking your rate won’t affect your credit score.
Need access under a slab? Tell us the run.
Plumber, GC, property manager, or homeowner, we'll scope the tunnel, dig it to plan, and back-fill it clean. Your licensed trade does the repair.
Now booking free inspections in Central Texas.