Most of what you will read on this comes from companies that only do one of the two. Foundation contractors favor tunneling. Some plumbers will not cut a slab at all. Both are telling you about their business as much as your house.
Tunneling vs. cutting the slab is usually presented as a two-way choice, and it isn't. There are four ways to reach a failed pipe under your foundation, and the right one depends on what is wrong with the pipe.
We look at the camera footage before we talk about methods. What's wrong with the line decides how we get to it. Below we cover what each method involves, what actually decides between them, the two options most articles skip, and the one question that matters more than which method you pick.
Both methods reach a pipe under your foundation. They differ in where the work happens.
Tunneling digs a passage under the slab from outside, usually from a flowerbed or the edge of the house. The slab stays intact. Crews work beneath your floors rather than on them, and you can normally stay in the home. Digs this deep fall under federal excavation and trenching safety rules.
Cutting the slab opens the floor from inside. Flooring comes up, concrete comes out, and the work happens in your living space. It reaches the pipe directly and takes less excavation.
Which fits depends on where the failure is, how far it sits from the perimeter, how many breaks there are, and what's on your floors.
Rerouting and lining are two other options worth asking about.
The work starts outside your house. Excavation usually begins at a flowerbed or along the edge of the foundation, wherever the approach to the failure is shortest.
From there, a passage gets dug under the slab. It runs roughly three feet wide and three feet tall, which is enough room for a plumber to work underneath with tools. Shoring goes in as the passage advances so the soil around it stays put.
Once the failed section is reachable, the pipe gets repaired or replaced and tested. That part is the same work a plumber would do anywhere else. The difference is only how they got there.
Then the tunnel gets filled back in. That step matters more than most homeowners realize, and we cover it in its own section further down.
Through all of it, nothing inside your home is opened. Your floors stay down, your furniture stays put, and you can usually keep living in the house while it happens.
This method goes straight down instead of underneath. The work happens inside the house, above the failure.
Flooring comes up first, whatever it is. Then the concrete gets cut and broken out, and the soil underneath is dug away until the pipe is exposed. The failed section is replaced and tested, the slab gets patched, and the flooring goes back.
| Tunneling | Cutting the Slab | |
|---|---|---|
| Where the work happens | Outside and underneath | Inside your living space |
| What gets disturbed | Landscaping and yard | Flooring, concrete, interior finishes |
| Can you stay in the home | Usually yes | Sometimes, depending on scope |
| Best case | Failure near the perimeter | Failure deep under the house |
| Worst case | Long passage under the center | High-end flooring above the failure |
The disruption is real. Cutting concrete indoors is loud, it produces dust, and equipment and excavated soil move through your house. Depending on the scope, some households stay somewhere else while it happens.
There is a genuine advantage on the other side of that. Cutting reaches the pipe by the shortest possible path. When a failure sits deep under the middle of the house, that path is a great deal shorter than a tunnel.
The method should come out of the diagnosis, not out of a preference. Five things settle it:
Where the failure sits. Near the perimeter favors tunneling, because the passage is short. Deep under the center of the house means a long tunnel, and cutting starts to make more sense.
How many breaks there are. One failure is a spot repair. Several point to a line reaching the end of its life, which changes the conversation entirely.
What is on the floor above. Tile, hardwood, and stone are expensive to remove and restore. Carpet over slab is not. That difference moves the math.
What sits above the failure. A pipe running under an interior wall, a kitchen island, or built-in cabinetry is a different problem than one under open floor.
The overall condition of the pipe. If the camera shows corrosion along the whole run, repairing one spot buys very little time.
None of those are opinions. They come from the camera and from looking at the house.
The camera answers most of this before anyone quotes a method. That's the order it should happen in.
Tunnel or cut is not the whole menu. Two other paths exist, and both deserve a mention before anyone starts digging.
Rerouting leaves the under-slab line where it is. The old pipe gets abandoned in place, and new pipe runs a different way, through walls, an attic, or around the outside of the house.
The appeal is straightforward. Nothing under your slab gets touched, and nothing under your slab can fail again on that run. You have moved the plumbing somewhere reachable.
The trade-off is interior work. Walls have to be opened where the new line passes, then patched, textured, and painted. That is real disruption, just a different kind than cutting a floor.
Rerouting makes the most sense when the existing line is failing broadly rather than broken in one place. If a camera shows an old line corroding along its length, replacing a single section is a short-term answer.
Lining is the other option. For certain failures, a liner gets installed inside the existing pipe, forming a new pipe within the old one.
It does not fit everything. A line that has collapsed, or where sections have shifted badly out of alignment, is not a candidate. But where it does fit, nothing gets dug.
Homeowners in other parts of the country rarely face this decision. Here it is routine, and the reasons are in the ground.
Houston homes are built on concrete slabs. There is no basement, so your supply and drain lines run underneath the concrete rather than in a space you can walk into.
Our clay soil does not sit still. It swells when it takes on water and shrinks when it dries out, and everything buried in it moves along with it. Over years, that constant shifting works pipe joints apart and cracks pipe that was fine when it went in.
Age compounds it. Established Houston neighborhoods still have cast iron sewer lines under the slab, and cast iron corrodes from the inside over decades. By the time it shows up as a problem, the whole run has usually been thinning at the same rate.
That is why a single break so often turns into a bigger conversation. The camera goes in to find one failure and shows a line that has more than one.
The soil matters to the method too. It is what a tunnel gets cut through, and what has to be put back afterward.
A tunnel is a void under your foundation. It stays a void until someone fills it back in, and how that gets done decides whether this repair causes you problems later.
Shoveling the dirt back and packing it by hand does not restore what was there. Soil under a slab was compacted by decades of weight sitting on it. Loose fill is not the same material, no matter that it came out of the same hole.
Proper backfill means mechanical compaction, or a pumped slurry that flows into the voids and sets up hard. Both restore support under the foundation. Neither happens by accident.
Under-compacted fill settles. Settlement under a foundation is the exact problem you were trying to avoid when you chose the method that leaves your slab intact.
Ask these before work starts:
Cutting the slab has its own version of this. Ask how the slab gets patched and how the patch ties back into the surrounding concrete.
Ask how the tunnel gets filled back in. The answer tells you a lot about who you're hiring.
Before you weigh methods, get the line looked at. The camera decides most of this, and it is the step that should come first.
We put a camera in the line, find the failure, and tell you what condition the rest of the run is in. Then we walk you through the options that fit your situation, including the ones that do not involve digging.
We have served Houston homeowners since 2003, and our team answers calls 24 hours a day. If you have sewage backing up, a warm spot on the floor, or water where it should not be, that is not a decision to research for a week.
We serve Houston and nearby areas including Spring, Humble, Kingwood, Klein, Tomball, Atascocita, Porter, Jersey Village, Conroe, Magnolia, Willowbrook, and The Woodlands.
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Business Address: 4001 Kendrick Plaza Dr, Houston, TX 77032
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Neither is better in general, and any contractor who says otherwise is describing their business. Tunneling keeps the work outside and your floors intact. Cutting reaches the pipe by the shortest path, which matters when the failure sits deep under the house.
Usually yes with tunneling, since the work happens outside and underneath. With slab cutting it depends on the scope, because the noise, dust, and equipment are inside your living space. Ask before the job starts rather than during it.
Done correctly, no. The risk is not the digging but the filling. A tunnel that is backfilled with loose, hand-packed soil can settle, so ask what compaction or slurry method will be used before work begins.
Rerouting abandons the under-slab line and runs new pipe through walls, an attic, or around the exterior. Whether it costs less depends on the length of the new run and how much interior wall work it takes. It fits best when the old line is failing broadly.
A camera goes into the line and shows the failure on screen. That footage tells us where the break is, how many there are, and what condition the rest of the run is in. All three shape which repair method makes sense.
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