Application
Plumbing Penetrations Through Concrete
Core holes and slab openings for supply, waste, vent, and drain lines through slabs, foundations, and walls.
Plumbing rough-in and remodel work needs penetrations for supply lines, waste and vent stacks, and floor drains. Getting a clean, correctly sized hole through a slab or foundation the first time saves the plumbing crew hours — and avoids the over-broken, oversized holes that leave gaps to patch and fire-stop.
In Houston, a large share of slab work happens over post-tension foundations and structural decks. That makes blind cutting risky: a waste line cored through a stressed tendon is both a structural failure and a schedule disaster. Crews we route work to scan first, mark tendons and rebar, and then core to the pipe schedule.
Coring and sawing for plumbing
Round penetrations for pipe are made with concrete core drilling, sized for the pipe plus sleeve and fire-stop clearance. Trenches for horizontal runs under a slab are cut with slab sawing and, where a longer utility trench is needed, trench cutting. Wall penetrations for stacks use wall sawing or coring depending on shape.
Before coring any structural slab, concrete scanning locates post-tension tendons, rebar, and existing lines so the penetration lands in a safe zone.
Practical considerations
- Wet coring keeps silica dust controlled per OSHA 1926.1153; slurry is contained and recovered on finished floors.
- Expansive clay soils common around Houston mean under-slab work should be backfilled and compacted properly to avoid future movement.
- Penetration diameter accounts for the pipe, sleeve, and annular fire-stop space.
- For remodels, existing embedded lines are scanned so a new core doesn't clip a live line.
Scan post-tension slabs
Never core a slab-on-grade or elevated deck for plumbing without scanning first — post-tension cables are common in Houston and unforgiving.
Plumbing penetration FAQs
- Can you core through a post-tension slab for plumbing?
- Yes, after scanning. The slab is scanned to map tendons and rebar; the core is then positioned in a clear zone. If a pipe location conflicts with a tendon, the plumber and crew adjust the layout.
- Do you cut trenches for under-slab plumbing?
- Yes. Horizontal runs are slab-sawn along the trench line and the concrete removed; longer or deeper utility trenches use dedicated trench cutting equipment.
- How big can plumbing cores be?
- Cores range from small supply-line diameters to large stack and drain sizes. The crew sizes each core to the pipe plus required clearance.
- Will coring flood the space with water?
- No. Wet coring uses controlled water volumes with vacuum recovery and containment, keeping the area clean while controlling silica dust.
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