SDS Breaker: The Complete Guide for UK Extension and Renovation Work
Everything you need to know about SDS breakers (kango hammers): hire vs buy, joule ratings for concrete slabs, chisel types, safe technique, and HAVS limits.
You hire a skip, clear the room, and start swinging a sledgehammer at the existing concrete floor. An hour later, your arms are wrecked and you've shifted half a square metre. The concrete is 125mm thick and reinforced with mesh. An SDS Max breaker would have done the same patch in ten minutes. This is the tool that turns a half-day of misery into a morning's work, and it's almost always hired rather than bought.
What it is and when you need one
An SDS breaker (also called a demolition hammer, kango, or concrete breaker) is a high-impact electric hammer that drives a steel chisel into concrete, masonry, or hard ground using a piston mechanism. Unlike an SDS drill, it does not rotate. It just hammers. All of its energy goes into breaking the material, which is why even a modestly powered electric breaker makes a sledgehammer look inefficient on anything thicker than about 75mm.
The piston mechanism is what separates a breaker from every other tool in the kit. A rotary hammer drill uses rotation combined with hammer action to drill holes. A breaker uses hammer action only, focused entirely on one point of the chisel. That single-purpose mechanism allows breakers to deliver impact energy that would destroy a drill mechanism in minutes.
You'll need one on any project that involves demolishing existing concrete floors, breaking through existing slabs to lay drainage, removing the footings of structures being demolished, or breaking out sections of masonry wall. On a kitchen extension, that typically means the groundwork phase: clearing the footprint, forming drainage penetrations through existing floor slabs, and occasionally removing sections of existing wall foundation.
If your project involves breaking through a floor slab to install drainage, locate the existing drainage runs first. A drain camera inspection costs £80-150 and tells you exactly where existing pipes run before you start swinging a chisel at the floor. Hitting a live drain you didn't know about costs far more to fix than the inspection.
SDS-Max vs SDS-Plus: they are not the same tool
This is the most common point of confusion for homeowners.
Your SDS Plus drill (the rotary hammer drill most homeowners already own) has an SDS Plus chuck. Some SDS Plus drills have a hammer-only mode, which lets you use them as a light breaker. They are not the same as an SDS Max breaker, and attempting to break a full concrete slab with an SDS Plus drill in hammer-only mode is how people burn out motors and waste a day making no progress.
The differences are substantial:
| Feature | SDS Plus drill (hammer-only mode) | SDS Max breaker |
|---|---|---|
| Chuck size | SDS Plus (10mm shank) | SDS-Max (18mm shank) — different chisel sizes |
| Impact energy | 2–5 joules | 8–30+ joules |
| Weight | 2–4 kg | 5–12 kg |
| Designed for | Drilling holes in masonry with hammer assistance; light chiselling | Breaking concrete slabs, demolishing masonry, sustained heavy impact |
| Motor rating | 600–1,100W | 1,100–1,750W |
| Daily use limit before HAVS risk | Can run longer between breaks due to lower vibration | Strict limits apply — see safety section below |
| Typical hire availability | Not usually available to hire separately | Standard hire item at all plant hire depots |
Budget SDS Plus breakers (tools marketed as stand-alone breakers with SDS Plus chucks, 5–8 joules) are adequate for removing ceramic tiles, chiselling out mortar joints, or taking the top off screed. They are not the right tool for breaking a 100mm concrete slab. Use an SDS Max machine for anything involving full slabs or blockwork.
Choosing the right joule rating
Joules (J) measure impact energy per blow. Higher joule ratings mean harder hits. But the joule figure is a guide, not a guarantee of performance. A quality 20J machine from a professional brand will outperform a budget tool claiming 40J, because build quality, blows per minute, and mechanism efficiency all matter beyond the headline spec.
That said, you do need to choose a tool with enough energy for your material:
| Material | Joule range needed | Typical extension task | Notes |
|---|---|---|---|
| Ceramic floor tiles on screed | 2–5J | Tile strip before screed removal | SDS Plus hammer-only mode works fine here |
| Sand/cement screed (50–75mm) | 8–15J | Removing existing floor screed | Medium SDS Max or budget SDS Max |
| Solid concrete slab (100–150mm) | 20–30J | Breaking existing floor for drainage, demolishing footprint | Dedicated SDS Max breaker — mid-range or above |
| Blockwork walls (100–140mm solid) | 15–25J | Removing sections of existing garden wall or outbuilding | Systematic approach needed — see technique below |
| Reinforced concrete (rebar present) | 30J+ or contractor | Foundations, structural slabs | Hire the heaviest available tool, or call a contractor |
Reinforced concrete changes the calculation entirely. When the chisel hits rebar, the breaker bounces off it or binds against it, and you lose most of your progress. If your survey reveals reinforced concrete in the footprint, establish the rebar density before committing to DIY breaking. Lightly reinforced slabs (mesh reinforcement) are manageable with a heavy hired breaker. Heavily reinforced structural concrete (close-spaced bar at 150mm centres or less) belongs with a specialist demolition contractor who can also dispose of the material safely.
How to use it properly
A breaker is not complicated to use, but bad technique makes it slow, exhausting, and hard on the tool. Good technique makes it fast and controlled.
Before you start
Mark the area to be broken. Work systematically from one edge rather than attacking the middle. Breaking from the edge lets the fractured concrete "give" laterally as it breaks, which dramatically reduces the effort needed. Starting in the middle of a slab gives the concrete nowhere to go and the chisel has to overcome the material in all directions at once.
Locate and mark any buried services. Before breaking any floor slab, know where your drains run. If your floor is near an external wall, consider whether there are any buried electrical cables, gas pipes, or water pipes below. Check utility drawings if they exist; if they don't, proceed carefully in a small test area first.
Check the voltage of your hired tool before you collect it. Most trade hire depots supply breakers at 110V, not 240V. A 110V tool requires a step-down transformer (a yellow box that converts 240V from a normal socket). Hire depots will also hire the transformer. If you turn up with a 110V tool and no transformer, you won't be using it that day.
Technique
Point the chisel at an angle of about 30 to 45 degrees to the surface rather than straight down (90 degrees). Angled impacts lever the concrete apart more efficiently than pure downward blows. Hold the tool firmly but not tensely, with both hands. Let the machine do the work. Pressing down hard doesn't increase the impact energy; the piston delivers the same joules whether you're pushing hard or just guiding.
Work a grid pattern. Break lines across the full width of the area at 100–150mm intervals, then cross-lines at right angles. This turns the slab into manageable chunks rather than irregular rubble that's awkward to lift. Chunks in the 10–15kg range are the target: small enough to carry out, large enough that you're not handling dust and splinters.
Create a starting edge whenever possible. If you're breaking at a doorway or a wall, start at that edge and work inward. If you're breaking in the middle of a room, use the angle grinder to cut a kerf (a scored line) across the slab first to create a clean working edge. This prevents cracking running unpredictably into areas you want to keep.
Never let the chisel bind in the concrete. If the chisel is stuck and the machine is hammering against a seized point, you are stressing the chuck, the chisel shank, and the mechanism simultaneously. Stop the machine, rock it slightly to free the chisel, then continue. Forcing a bound breaker is the fastest way to damage a hire machine and get charged for it.
After breaking
Concrete rubble is heavy. A square metre of 100mm slab weighs around 240kg. Plan the removal before you start breaking: a standard 6-yard skip holds about 2 tonnes of concrete, so a 20m2 floor (4,800kg) fills two skips. Arrange removal as you go rather than piling rubble in a corner that becomes impossible to shift.
Chisel types
Three chisel profiles cover virtually every task on an extension project:
Pointed chisel (moil point) - the pointed tip concentrates the full impact energy into a very small area, which maximises penetration into hard concrete and dense masonry. The go-to choice for breaking slabs and blockwork. It creates rubble rather than clean cuts.
Flat chisel - a wider, flat blade that cuts along a line rather than breaking in all directions. Use it for removing surface screed cleanly, chiselling out mortar joints, removing tiles without destroying the substrate underneath, and breaking along a defined line where you need a reasonably straight edge.
Clay spade - a wide, angled blade like a narrow garden spade. Designed for excavating and lifting, not punching through hard material. Use it for breaking up compacted clay sub-base, lifting sections of loose screed or shallow hardcore, or cutting through softer sub-floor material.
Chisels are typically included with a hired breaker. If you're buying, they're sold separately: SDS-Max chisels cost £8–25 each depending on type and quality. Keep them sharp: a blunt chisel bounces off the surface rather than cutting into it, which transfers more vibration to your hands.
Hire vs buy
For a one-off extension project, hire. The decision is straightforward.
| Factor | Hire | Buy |
|---|---|---|
| Cost for 2 days' use | £40–160 depending on supplier and size | £70–560 depending on spec — plus you own a tool you'll rarely use again |
| Quality of tool available | Professional-grade Hilti or Milwaukee from a trade depot | Budget to mid-range for same spend as hiring |
| 110V vs 240V | Hire depots supply 110V — need transformer (also hireable) | Buy 240V models for domestic use; no transformer needed |
| Maintenance | Depot's problem | Your problem |
| Who it suits | Homeowners breaking 5–50m2 once or twice in a build | Tradespeople or homeowners with multiple renovation projects per year |
A Hilti TE 700-AVR at a Speedy depot costs over £1,700 to buy. Hiring it for a day or two is the obvious call. The community consensus on this is unanimous: hire a good tool rather than own a bad one, and the quality difference on a breaker is substantial.
The only scenario where buying makes sense for a homeowner is if you're managing several renovation projects over a few years and will genuinely accumulate ten or more days of breaker use across them. At that point, a mid-range SDS Max at £150 – £250 pays back against hire rates within a year.
For most people: hire it. You'll use it for one or two days on the whole project.
Hire rates:
Collected from a local depot: £20 – £35
Delivered to site: £60 – £80
Weekly rate if the project runs long: £50 – £100
Note that the daily hire rate from National Tool Hire includes delivery and VAT (around £75/day), which is genuinely all-in pricing. A local depot rate requires you to collect and return the tool yourself. Factor in your time and fuel if the depot is not nearby.
What to buy (if you're buying)
Budget: £70 – £140
At the lower end of the budget range, the Einhell TE-DH 5 (SDS Plus, 5J, around £70 at Screwfix) handles tile removal and light surface chiselling. It is genuinely underpowered for concrete slabs. At the upper end, the Einhell TE-DH 12 (SDS Max, 12J, around £130) and the Titan TTB811DRH (Hex mount, 16.4kg, around £140) are heavier tools that will break screed and lighter masonry, though they struggle with thick reinforced slabs.
Budget machines are serviceable for extension-scale work if your breaking task is screed and single-skin blockwork rather than full concrete slabs. They lack the build quality and anti-vibration systems of professional tools, which matters for sustained use (see the HAVS section below).
Mid-range: £150 – £250
The Erbauer EBR1750 (Hex, 15kg, around £220 at Screwfix) is the main option at this tier from the Screwfix own-brand range. It handles concrete slabs adequately, though it's heavy. At this price point, the community frequently suggests that hiring a better Hilti or Milwaukee for the day is better value unless you plan to use it repeatedly.
Professional: £390 – £560
Three tools dominate at this tier. The Makita HM0870C/2 (SDS Max, 7.6J, 5.1kg, around £390) is the lightest in the professional category and includes low-vibration design. The DeWalt D25899K-GB (SDS Max, 26J, 9.9kg, around £530) delivers significantly more impact energy for thick slabs. The Bosch GSH 5 CE (SDS Max, 8.3J, 6.2kg, around £560 for 110V) is a compact professional machine favoured by electricians and plumbers for channel cutting.
At this price point, you're buying what hire companies stock. Hiring a Hilti TE 700-AVR for two days costs £80–160 and gives you a tool that outperforms even the professional-tier bought options above.
HAVS and vibration: what you actually need to know
HAVS (Hand-Arm Vibration Syndrome, also known as vibration white finger) is an irreversible condition caused by prolonged use of vibrating tools. It starts as tingling or numbness in the fingers after tool use. It progresses to permanent loss of sensation, pain in cold conditions, and in severe cases inability to grip. It cannot be cured, only slowed by stopping vibration exposure.
Concrete breakers are flagged by the HSE as particularly high-risk tools. The Control of Vibration at Work Regulations 2005 set an Exposure Action Value (EAV) of 2.5 m/s² A(8) (the level at which employers must begin taking protective action) and an Exposure Limit Value (ELV) of 5 m/s² A(8), which must not be exceeded. Most SDS Max breakers have vibration emission values between 10 and 20 m/s², which means the EAV is exceeded very quickly.
The practical consequence for a homeowner:
The HSE guidance for construction workers states that high risk begins after about one hour of hammer action tool use per day. Medium risk begins after about 15 minutes per day. These are not precise cut-off points, but they tell you something important: you should not run an SDS breaker for four hours straight and assume you're fine because you're only using it for one project.
For a homeowner breaking 5–10m2 of 100mm slab over a single day, the exposure is manageable with breaks. For a two-day breaking job, take at minimum ten minutes away from the tool every hour. Stop immediately if you notice tingling or numbness in your fingers that persists after you put the tool down.
Anti-vibration systems (sold under names like AVR, AVT, AVS, or AVC depending on the brand) reduce but do not eliminate vibration transmission to the handles. If you're comparing hire options, prefer a machine with an active anti-vibration system. Hilti's AVR (Active Vibration Reduction) and Bosch's AVT (Anti-Vibration Technology) genuinely reduce the vibration reaching your hands compared to unprotected machines.
Tingling or numbness in your fingers during or after using a breaker is a sign you've exceeded your safe exposure for that session. Stop, rest, and do not continue breaking work that day. Persistent tingling after a night's sleep means you should see a GP before using any heavy vibrating tool again. HAVS is classified as an industrial disease and is compensable, which tells you how seriously the medical profession treats it. Take the exposure limits seriously.
PPE: the non-negotiables
Ear defenders. SDS Max breakers run at 100–108 dB(A). The legal eight-hour exposure limit for hearing damage is 85 dB. At 105 dB, you reach the daily dose limit in under five minutes. Wear ear defenders every time you pull the trigger, without exception.
Eye protection. Flying concrete fragments are not small. Safety glasses at minimum; a full face shield is better when breaking overhead or at floor level where ricochet is unpredictable.
FFP3 dust mask. Breaking concrete generates silica dust. Silicosis (lung damage from silica inhalation) is irreversible and fatal in severe cases. The HSE estimates over 500 construction workers die from silica-related lung disease each year in the UK. Breaking inside an existing building amplifies the risk, as the dust has nowhere to go. Wet the surface slightly before breaking to suppress dust, and wear an FFP3 mask throughout.
Steel-toecap footwear. A 10kg fragment of concrete falling onto unprotected feet is a fracture. This is not optional.
Anti-vibration gloves. Proper anti-vibration gloves (EN ISO 10819 certified, not regular work gloves) reduce high-frequency vibration transmission and provide grip. They don't eliminate HAVS risk but they reduce it and protect against cuts from sharp-edged fragments.
When to stop and call a contractor
Three situations where self-managing the breaking is the wrong call:
Reinforced concrete with dense rebar. If you cut through the slab surface and find steel bar at close centres (under 200mm spacing), the breaking will be slow and physically punishing. A demolition contractor with a breaker attachment on a mini-excavator will do in two hours what takes a person two days. Get quotes before committing to a manual breaking approach.
Structural elements. If the concrete you're breaking is part of the building's structural load path (an existing foundation, a load-bearing ground beam), don't proceed without sign-off from your structural engineer on what can be removed and in what sequence. This is not about the tool; it's about not undermining the building.
Large volumes. Breaking and removing more than about 15–20m2 of 100mm slab manually is a full day's hard physical labour for a fit person. Beyond that scale, a hired mini-excavator with a hydraulic breaker attachment costs around £250–400/day and is operated with no vibration risk to you. For groundworks on a full kitchen extension footprint, discuss the plant hire option with your groundworker rather than assuming manual breaking.
Alternatives
An SDS drill in hammer-only mode works for very light chiselling and tile removal (up to 5J impact energy). The moment you're facing a real concrete slab, it's the wrong tool.
A sledgehammer is useful as a follow-up tool once the breaker has cracked the concrete. It shifts large broken pieces and finishes the job, but it's inefficient as the primary method on anything over 75mm thick. Use the breaker to crack; use the sledgehammer to shift.
An angle grinder with a diamond blade cuts a clean kerf line in concrete before breaking, which gives the breaker a clean edge to work to and prevents cracking running into areas you want to preserve. Use both together on any break where the edge quality matters.
Where you'll need this
SDS breakers appear in the demolition and groundwork phases of any extension or renovation project:
- Foundations and footings - breaking out existing concrete in the new footprint before excavation begins
- Drainage - penetrating existing floor slabs to connect new drainage runs to the main sewer
- Groundwork - general demolition of hard surfaces and existing structures within the build footprint
- Walls and blockwork - removing sections of existing masonry to form the new structural opening between extension and house