For structural & geotechnical engineers

Engineer-Access Tunnels for Under-Slab Evaluations

An engineer can't certify what they can't see. When an under-slab evaluation needs eyes on a grade beam, a suspected void, a moisture source, or a plumbing penetration, we dig the access to your specification. Clean, shored, and safe to enter.

Get a Tunneling Quote (210) 816-0034

A clean access opening at a stucco foundation wall, entry for an under-slab evaluation.

Engineers rarely hire the digger directly, but the dig still decides whether the observation is worth anything. Dig it wrong and the beam is buried under spoil, the bore is too tight to photograph from, and nobody will crawl into it. We work to your drawing or your field direction on three points. Where to enter, how far to reach, what to expose. Because we run foundation repair crews ourselves, we already speak the vocabulary, settlement versus heave included, and we document what we open.

“Engineer-access excavation for under-slab evaluations”“Observation tunnels to grade beams, voids, and penetrations”“Pre-repair access excavation to a structural engineer's specification”

When you call us

The jobs that need a tunnel.

Observe a grade beam or footing

The evaluation hinges on the condition of a beam nobody can see from above. We expose it cleanly enough to be measured and photographed.

Confirm or rule out a void

Suspected separation between slab and soil has to be verified. We open access to the area in question and leave the interface visible.

Trace a moisture or soil problem

Wet clay, a leak, or a bearing-soil concern under the slab needs to be seen at the source, because nothing reads accurately through concrete.

Inspect a plumbing penetration

Where a line passes through or under the foundation, the engineer needs to see the detail. We expose it without disturbing the line.

Pre-repair scope verification

Before a repair plan is finalized, an engineer wants conditions confirmed firsthand. Access first, plan second.

What you get

How we work with you.

An access dig for an engineer is a precision job, not a hole. The entry point, the reach, and the exposure come from your direction. The bore is shored and inspected by a competent person before anyone goes under it, and we photograph the opening so it can go into the record rather than being described from memory. When the evaluation is done we backfill and compact, or we leave the access open and protected if a repair follows immediately. Sort one thing out before we close it. Tell us which angles and which measurements your report needs. Once the tunnel is backfilled, getting them again means paying to dig twice.

SCOPE OF WORK

Access dug to the engineer's entry, reach, and exposure spec
Shored, OSHA-compliant bore safe to enter and observe in
Grade beams, voids, penetrations, or soil exposed cleanly
Photo documentation of opened conditions
Backfill and compaction, or protected open access for an immediate 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.

VEL

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.

PRC

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.

SAF

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.

STD

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.

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

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.

Industry FAQ

Structural engineers tunneling, questions answered.

Will you dig to our drawing or field direction?

Either. Give us the entry point, the reach, and what you need exposed and we'll dig to it. If you'd rather direct it on site, our competent person works with you in the field. The goal is that you observe exactly what you came to observe.

Is the access safe to enter for an inspection?

Yes, and that one is non-negotiable. Tunnels and trenches are shored and worked to OSHA Subpart P excavation practice, with safe access and egress and a daily competent-person inspection, before anyone goes underneath.

Do you document the opened conditions?

We photograph the access and what it exposes so it can go straight into your report or the project record. If you need specific angles or measurements captured, tell us before we backfill.

Can the repair follow immediately?

Yes. If your evaluation leads to a repair, we can keep the access open and protected and roll straight into foundation repair tunneling and pier installation, or hand off to the contractor of record.

Who pays for the access dig?

Whoever engaged you, usually. We invoice the homeowner, the contractor, or your firm, whichever the project is set up for, and we scope the access separately from any repair so the observation cost stands on its own in the file.

From real jobs