Concrete coring is a precision job that requires specialized equipment and skilled technicians—but how long it actually takes depends on several factors specific to your project. Whether you're drilling holes for HVAC ducts, plumbing, electrical conduit, or structural analysis, the timeline varies dramatically based on slab thickness, diameter, reinforcement, and site conditions. Understanding realistic timelines helps you schedule crews, manage project costs, and avoid costly delays.
Typical Coring Job Duration
A straightforward concrete core—say, a 4-inch diameter hole through a 6-inch slab with minimal rebar—usually takes 30 minutes to 2 hours from start to finish. However, larger diameters or thicker slabs can stretch to 4–8 hours or even multiple days for complex jobs.
The actual drilling typically accounts for only 20–40% of the total time on-site. Setup, surface prep, dust control, slurry management, and cleanup often consume as much time as the drilling itself.
Factors That Extend Coring Time
Concrete thickness and density is the primary driver. A 12-inch slab takes considerably longer than a 4-inch one. Post-tensioned concrete, reinforced with high-strength steel, and hard aggregates all slow drilling speed.
Hole diameter matters exponentially. A 2-inch core drills in minutes; an 18-inch core can take hours. Larger holes require more durable bits, slower feed rates, and often multiple passes to manage heat and vibration.
Rebar and post-tension cables force operators to work deliberately. If drilling encounters steel, the operator must slow down, apply additional coolant, and potentially reposition. Some contractors charge premium rates for heavily reinforced concrete or demand video inspection beforehand.
Access and site conditions impact scheduling:
- Tight spaces or floors above living/working areas require noise and dust containment (slowing the job by 1–3 hours)
- Multi-level buildings may need coordination with other trades
- Outdoor slabs exposed to weather might require tarping or rescheduling
- Existing pipes, conduit, or embedded utilities in the coring path can halt work mid-job
Slurry disposal and cleanup add 30 minutes to 2 hours depending on volume and site restrictions. Indoor jobs often require wet vacuuming and floor protection; outdoor work may allow runoff control to drain.
Project Scope Considerations
Single-hole jobs are priced and scheduled differently than multiple cores. A contractor drilling three 4-inch holes in the same slab might complete the work in 1–2 hours total; drilling the same holes in three separate slabs across different floors could take a full day.
Large-scale projects—such as coring 20+ holes for a commercial retrofit—are often scheduled in phases. Expect 2–5 days depending on hole count, slab accessibility, and coordination with other trades.
Scheduling and Coordination
Reputable concrete coring contractors typically arrive with crew, equipment, and materials ready to go. However, booking 2–4 weeks ahead is normal in busy markets. Last-minute rush jobs incur 25–50% surcharges.
Coordination matters. If your project involves multiple trades, confirm coring timing with electricians, plumbers, and HVAC crews beforehand. Conflicting site schedules are a common reason for delays.
Cost Implications of Time
Most concrete coring contractors charge by the hour ($75–$150/hour in major markets), per hole ($100–$400 depending on size and depth), or as a flat project fee for bundled work. Understanding the time investment helps you negotiate fair pricing and avoid low-ball bids from inexperienced operators.
Slower work isn't always worse—it often reflects proper dust control, careful rebar management, and attention to concrete integrity. A job quoted at 6 hours with full containment is usually preferable to one quoted at 2 hours without.
If you're comparing multiple contractors, confirm whether their quotes include travel time, setup, slurry disposal, and surface cleanup. This transparency prevents sticker shock and scheduling surprises.
Finding the Right Contractor
Concrete coring is specialized work, and experience matters. Use Mercoly to compare trusted concrete cutting and coring providers in your area—read reviews, verify equipment quality, and confirm insurance before committing. A contractor experienced with your slab type, reinforcement pattern, and access constraints will deliver accurate time estimates and professional results.
Frequently Asked Questions
Q: Can concrete coring be done through reinforced concrete without damaging the rebar? Yes, experienced operators use video scanning beforehand to map rebar locations and avoid cutting steel. If rebar must be cored, it significantly extends the timeline and may require structural engineering approval.
Q: What's the difference between time spent on a residential versus commercial concrete coring job? Commercial jobs often involve thicker slabs, heavier reinforcement, tighter coordination with other trades, and stricter dust/noise controls, adding 2–4 hours versus a straightforward residential slab.
Q: Do I need to be present while concrete coring happens? It's wise to be on-site or have a representative present to confirm hole locations, address unexpected obstacles, and authorize scope changes—this prevents re-do work that doubles your timeline and budget.
Compare concrete coring contractors on Mercoly today to get accurate quotes and reliable service.