How do I break up a concrete slab or base safely?

This is one of the few genuinely arduous DIY jobs, and the difference between a hard day and an impossible week is technique rather than strength. Concrete resists compression brilliantly and shatters readily once it can flex. Every hit in the middle of a well-supported slab is absorbed; every hit near a free edge does work.

Safety

What you'll need

• A properly fitted FFP3 mask, goggles and ear defenders
• Heavy gloves, boots with toe protection, and long sleeves
• A hired electric or hydraulic breaker, or a sledgehammer for thin slabs
• Water for dust suppression, and a way to keep applying it
• A skip, grab lorry or a tip run arranged in advance
• A pick or a crowbar for levering broken sections
• A disc cutter or floor saw for cutting a clean line

Step by step

1. Find out what is under it.Drainage, gas, water, electricity and telecoms all get run under and beside slabs, sometimes very shallowly. Check drawings if you have them, look at where manholes and meters are, trace the likely runs, and use a cable and pipe detector. If there is any chance of a live service, get it located properly.
2. Find out what it is doing.If the slab supports anything — a wall, a step, a post, a building — stop. A slab that is part of a structure is a structural element and removing it needs advice and, often, temporary support.
3. Establish the thickness and whether it is reinforced.Drill a test hole or break a small hole at an edge. A 75mm unreinforced garden slab is a different job from a 200mm reinforced drive, both in effort and in the tools needed. Reinforcement means you will also be cutting steel.
4. Arrange the disposal before you start.Broken concrete is around two tonnes per cubic metre. A modest slab fills a skip with weight long before it fills it with volume, and overloaded skips will not be collected. Ask the skip company for a heavy-materials or grab option, and check whether a skip on the road needs a highway permit.
5. Start at an edge or make a hole.If there is a free edge, work from it. If not, break one hole right through somewhere near an edge and then work outwards from that hole. Concrete needs somewhere to move into.
6. Cut a line if you only want part of it out.A disc cutter or a hired floor saw cut through the full depth along the line gives you a clean edge and stops the break running into concrete you want to keep. Wet-cut it — dry cutting concrete is one of the highest silica exposures there is.
7. Break in manageable pieces.Work along the free edge in strips, breaking pieces you can actually lift or barrow. Trying to break large slabs and then move them is how people hurt their backs.
8. Angle the breaker rather than driving it straight down.A point driven vertically into the middle of a supported slab just punches a hole. Working at an angle a little back from the free edge levers pieces off and is far more effective.
9. Keep it wet.Continuous water onto the cutting or breaking point suppresses most of the dust. A hose on a trickle, an assistant with a garden sprayer, or an on-tool water feed. This is the single most important control and it costs nothing.
10. Cut the reinforcement as you go.Bolt croppers or a disc cutter on the exposed steel. Do not try to pull mesh out with a breaker still running, and mind the ends, which spring and are at shin height.
11. Work in short spells.Breakers transmit serious vibration into the hands and arms, and hand-arm vibration syndrome is permanent. Take regular breaks, share the work, keep your hands warm, and do not grip harder than you need to.
12. Clear as you go.Barrow the rubble out in stages rather than building a heap you then have to move twice. Keep the working area clear so you are not standing on broken material while swinging a breaker.

Tips

• Concrete is accepted as clean hardcore at most tips and by aggregate recyclers, often more cheaply than general waste — but only if it is genuinely clean, with no timber, plastic or soil mixed in. Keep it separate.
• If you find any material you suspect might contain asbestos — old corrugated sheet, certain boards, some old floor tiles and their bitumen bedding — stop immediately and get it identified before doing anything else.
• Hire the breaker for two days rather than one. Rushing this job is how people get hurt.
• Wet the slab and the rubble down before barrowing and before loading a skip, to keep the dust down at every stage rather than just at the breaking.

Alternatives

• Sledgehammer: Viable for thin, unreinforced, small slabs — a path, a small shed base, a step. Free if you own one, exhausting quickly, and hopeless on anything thick or reinforced.
• Electric breaker (hired): The usual domestic answer. Manageable weight, plugs into a normal socket, and takes most domestic slabs. Hire by the day and get the moil point and a chisel point with it.
• Hydraulic breaker on a mini-digger: For a large drive or a big base. Fast, and needs machine access and someone who can operate it. Often the cheapest route once the area is substantial, when the day rate is set against a week of hand work.
• Contractor with a grab lorry: Break-out and removal in one. Worth pricing before committing to a week of hire and skips — for a full drive the difference is often smaller than expected.
• Leave it and build over it: Sometimes the right answer. A sound slab can be a sub-base for something else, and breaking out concrete that does not need to go is a great deal of work for nothing.