For foundation repair · The work we know best
Foundation Repair Tunneling & Interior Pier Access
Sometimes the piers a house needs sit in the middle of the slab, not at the perimeter — and breaking the finished floor to reach them is the most disruptive, expensive way to do it. We tunnel under the slab instead, so interior piers go in from below and the floors above stay whole.
This is the work Motmot knows from the inside out — we run our own foundation repair crews. When the elevation survey calls for interior support, or an engineer needs to reach a grade beam or a plumbing penetration, a tunnel is almost always cleaner than cutting the slab. We dig the access to the marked pier locations, keep the under-slab plumbing protected while the lift happens, and backfill and compact when the piers are set.
When you call us
The jobs that need a tunnel.
Interior piers required by the survey
The floor sinks toward the center, not the edge. Interior piers are the fix — and tunneling reaches them from below without sawing through tile, wood, and the rooms above.
Engineer requires under-slab access
A structural engineer needs eyes on a grade beam, a void, or a moisture problem under the slab before signing off. We open the access they specify.
Plumbing must be protected during the lift
When a house is leveled, the rigid drain lines under it are stressed. Tunneling lets the plumbing be inspected and protected — or repaired — as part of the same dig.
No exterior access to the work area
Tight lot lines, additions, or hardscape block the spot that needs support. A tunnel reaches it from a workable entry point instead.
Keeping the home livable
Tunneling from outside or from a single interior entry keeps most of the house usable while the structural work happens underneath.
What you get
How we work with you.
Because the crew tunneling for the piers and the crew setting the piers come from the same shop, the hand-off is seamless — the access lands exactly where the pier plan needs it, at the right depth, with room to drive and cap. We've also dug enough of these to protect what's down there: we know where the sewer and supply lines run under a typical Central Texas slab and we keep them safe while the structure comes back toward plane. When the piers are in, we backfill and compact in lifts so the repair stays put.
SCOPE OF WORK
- Tunnels dug to the marked interior pier locations, at pier depth
- Under-slab plumbing located and protected during the lift
- Engineer-access openings dug to spec where required
- Backfill and compaction in lifts once piers are set and capped
- Coordinated with the same crew that performs the repair
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 a plumbing or foundation job. We staff the bore to the schedule, dig in clean shifts, and hand the plumber an open, ready trench so their billable hours aren't spent waiting on a shovel.
Precision
We dig to the plan — depth, width, and pitch shot before the first spade, then verified as we go. The pipe run, the pier location, or the engineer's access point lands where the drawing says it should, the first time.
OSHA safety
Tunneling and trenching carry real cave-in exposure. 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: width to work in, clean floor and walls, true pitch, and a documented hand-off. Backfill is placed and compacted in lifts so the ground — and anything on it — settles right.
Standards & compliance
Texas 811 is called and lines are located before we dig. We sell the access, not the licensed pipe work — your plumber stays the plumber. Permits, locates, and clean documentation come standard.
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 under a slab actually runs, where the belly usually hides, and how much room a plumber needs to set a fitting, swing a saw, and lie comfortably to make a joint. We open the work area wider where the repair is, shore it, keep it dry, and light it — then get out of the way. The plumber shows up to a tunnel they can work in, not a hole they have to fight. That's the difference between a bore dug by people who've only moved dirt and one dug by a foundation crew who has watched the pipe work happen a hundred times.
- We open the work area wider where the repair is — 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
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 to your licensed plumber, foundation crew, or engineer — open, dry, and workable.
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 — Tradesman, Journeyman, Master, and Inspector licenses. Motmot sells under-slab tunneling and access excavation; we partner with your licensed plumber for the pipe repair itself. And before any dig, Texas 811 is contacted at least two business days ahead so gas, water, and utility lines are located first.
Industry FAQ
Foundation repair tunneling — questions answered.
From real jobs
What this access looks like on real jobs.
Tunneling for other industries
Plumbing companies
Under-slab tunneling for plumbers.
See plumbing companies tunneling →Structural engineers
Engineer-access excavation for under-slab evaluations.
See structural engineers tunneling →GCs & remodelers
Under-slab access for remodel plumbing.
See gcs & remodelers tunneling →Property mgmt & multifamily
Low-disruption under-slab tunnel access for rental and multifamily properties.
See property mgmt & multifamily tunneling →Investors & flippers
Pre-sale and investor property tunneling for plumbing/foundation access.
See investors & flippers tunneling →Realtors & inspectors
Under-slab access for repair work before closing.
See realtors & inspectors tunneling →Restoration & insurance
Access excavation for slab leak and water-damage repairs.
See restoration & insurance tunneling →Commercial facilities
Commercial under-slab tunneling for plumbing and structural access.
See commercial facilities tunneling →Backfill & cleanup
Tunnel backfill and cleanup.
See backfill & cleanup tunneling →Need under-slab access? Tell us the run.
We'll scope the tunnel, dig it to plan, shore it, and back-fill it clean — so your licensed repair goes in smoothly and the floors above stay whole.
Now booking free inspections in Central Texas.