Quick Answer

Yes — you can drill a horizontal hole under a driveway or slab with a core drilling rig laid on its side, a long wet core bit and steady water flow. The key challenges are keeping the rig square, managing water and slurry underground, and using a bit long enough to reach the full depth. Plan the drainage of the drilling water before you start.

What You Need

• Core drilling machine with side-mount rig or a purpose-built horizontal frame.
• Long wet core bit or threaded extension tubes for depth.
• Water supply and a slurry collection pit at the far end.
• Anchor points — a horizontal rig needs solid bracing.

How to Drill Horizontally Under a Slab

• Excavate access pits at both ends so you can see the breakout point.
• Set the rig on timber cribbing and brace it against the slab edge.
• Align the barrel with the target line using a laser or string line.
• Drill with light feed; horizontal holes let cuttings settle in the barrel.
• Withdraw and clear the barrel every 100-150mm of progress.
• Collect the breakout slurry at the far pit — never let water run uncontrolled.

Horizontal Drilling Tips

Challenge	Solution
Rig movement	Brace against slab and stakes
Cuttings build-up	Frequent barrel withdrawal
Keeping level	Laser alignment, check every 100mm
Water management	Far-side collection pit + pump

Safety Tips

• Check for buried services before excavating or drilling.
• Ensure the breakout area is clear of people.
• Use a long wet bit — see the diamond core drill bits and extension options for horizontal work.

Frequently Asked Questions

Q: Can I drill a horizontal hole without a special rig?

A: A handheld drill is unsafe and inaccurate for long horizontal holes. Use a side-mount rig or a purpose-built frame.

Q: How long can a horizontal core hole be?

A:With continuous threaded tube extensions, contractors drill 1m+ horizontal holes. Depth depends on machine power and bit diameter.

Q: What diameter should the hole be for a cable or pipe?

A: Size the core bit 10-20mm larger than the sleeve or pipe. See the continuous threaded tube drill for extension sections.

Conclusion

Horizontal core drilling under a slab works when the rig is braced, the alignment is laser-checked and the water is managed. JOY TECH supplies bits, extensions and accessories for horizontal work; contact us for project support.