Cutting and Drilling Concrete: Tools, Techniques and What to Rent

Concrete modification ranges from drilling a single anchor hole (10 minutes) to cutting out a full slab section (full day). Before starting any concrete project, know your slab dimensions--use our concrete calculator to understand what you're working with in terms of volume and replacement costs if needed.

Choosing the Right Tool

The tool depends on what you're doing. Using an undersized tool on concrete is frustrating at best and dangerous at worst.

For Drilling Holes

Tool	Hole Size	Best For	Own vs. Rent
Hammer drill	Up to 1/2 inch	Anchors, tapcon screws, small fasteners	Buy ($60-150) if you'll use it again
Rotary hammer	1/4 to 1-1/2 inch	Larger anchors, sleeve bolts, conduit	Rent ($40-60/day) for occasional use
Core drill	1 to 6+ inches	Plumbing, electrical conduit, HVAC penetrations	Rent ($75-150/day)--specialized tool

For Cutting

Tool	Cut Depth	Best For	Rental Cost
Angle grinder (4.5-7 inch)	Up to 2.5 inches	Score lines, small cuts, crack chasing	Buy ($40-80)
Cutoff saw (14 inch)	Up to 5 inches	Section removal, trench cuts, expansion joints	$60-90/day
Walk-behind slab saw	Up to 6+ inches	Long straight cuts, saw-cutting joints, road work	$150-250/day

For most homeowner projects, an angle grinder plus a rotary hammer covers 90% of concrete modification needs.

Cutting Concrete: Step by Step

Before You Cut

1. Check for utilities. Call 811 (free) to mark underground lines before cutting outdoor slabs. Indoors, use a stud finder or wire detector to check for electrical conduit and plumbing in or beneath the slab.
2. Check for rebar. A rebar locator or even a stud finder in metal-detect mode identifies reinforcement locations. Adjust your cut line if possible.
3. Mark your cut. Use chalk line for straight cuts. For curves, use a garden hose as a template, then mark with spray paint.

Making the Cut

For a concrete saw or angle grinder with diamond blade:

1. Set your cut depth--for a 4-inch slab, you can cut full depth with a 14-inch cutoff saw or score 2 inches deep with a grinder and break the rest
2. Start the saw and let it reach full speed before contacting the concrete
3. Lower the blade slowly into the starting point--don't plunge
4. Move at a steady pace: approximately 1 foot per minute for full-depth cuts in 4-inch concrete
5. Let the blade do the cutting--forcing it causes overheating and blade damage
6. Use water if available--wet cutting reduces dust by 85% and extends blade life significantly

Dust control is critical. Concrete dust contains silica, which causes permanent lung damage. Wet-cut whenever possible. If dry-cutting, wear an N95 or P100 respirator (not a paper dust mask) and cut in a well-ventilated area.

Removing a Section

If you're cutting out a section to pour new concrete next to existing:

1. Cut all lines to full depth
2. Break the section with a sledgehammer starting from the center
3. Pry out pieces with a flat bar
4. Clean the edges with a grinder for a smooth joint face

For full slab demolition and removal, the process scales up with larger tools and disposal planning.

Drilling Concrete: Step by Step

Choosing Drill Bits

• Carbide-tipped masonry bits: Standard for holes up to 1/2 inch. Cheap but wear out faster. Good for a few holes.
• SDS-plus bits: For rotary hammers. Faster, last longer, better chip removal. Required for holes over 1/2 inch.
• Diamond core bits: For holes 1 inch and larger. Expensive ($30-100 each) but cut clean holes through rebar and aggregate.

Drilling Technique

1. Mark your hole location with a center punch or nail
2. Start drilling at slow speed without hammer mode to establish a guide groove
3. Once the bit is seated (about 1/4 inch deep), engage hammer mode
4. Apply firm, steady pressure--don't lean your body weight into it
5. Withdraw periodically to clear dust from the hole
6. For holes deeper than 2 inches, clear dust more frequently to prevent bit binding

Common Drilling Mistakes

• Drilling too close to edges: Keep holes at least 3 inches from any edge to prevent cracking
• Hitting rebar and forcing through: Stop, move the hole location, or switch to a diamond bit. Understanding when and where rebar is used helps you anticipate reinforcement before cutting.
• Overheating the bit: If you see smoke or the bit glows, stop and let it cool. Dip in water between deep holes.
• Wrong bit for the tool: SDS bits don't fit regular drills. Masonry bits in a regular drill (without hammer mode) will take forever and burn out.

Safety Requirements

Concrete cutting and drilling demand respect. At minimum:

• Eye protection: Safety glasses with side shields (or goggles for overhead drilling)
• Hearing protection: Concrete saws hit 100+ dB--permanent hearing damage in minutes
• Respiratory protection: N95 respirator minimum for dry cutting; P100 for extended work
• Gloves: Leather or heavy-duty work gloves--vibration and flying chips are constant
• Steel-toed boots: Falling concrete chunks are heavy
• Long sleeves: Concrete dust is alkaline and irritates skin

Never cut concrete alone. Have someone nearby who can call for help or cut power to the tool if something goes wrong.

When to DIY vs. Hire a Pro

Some concrete cutting is straightforward DIY. Some isn't.

DIY-friendly:

• Drilling anchor holes for posts, brackets, or tapcon screws
• Cutting a small section (under 4 sq ft) with an angle grinder
• Score-and-snap cuts for removing a single damaged slab

Hire a professional for:

• Cuts near utilities or structural elements
• Core drilling through walls or foundations
• Removing large sections (over 20 sq ft)
• Any cut that could affect structural integrity

If your cut creates damage that needs patching, our guide on how to repair cracks covers filling and sealing techniques. The DIY vs. contractor decision depends on scope, tool availability, and your comfort with powerful cutting tools. Renting tools you've never used for a one-shot concrete job is where most injuries happen.

Key Takeaways

• Match the tool to the job--angle grinders for small cuts, cutoff saws for section removal, rotary hammers for drilling
• Always check for utilities and rebar before cutting
• Wet-cutting reduces silica dust by 85% and extends blade life
• Keep drill holes at least 3 inches from edges to prevent cracking
• Rent specialized tools rather than buying for one-time use--expect $100-200 total for a weekend project
• Hire a pro for cuts near utilities, structural elements, or anything over 20 sq ft

For more project guidance, browse our complete library of concrete guides and tutorials.