Block, Brick or Poured Concrete: Which Rotary Hammer Do You Actually Need?
Last updated: October 26, 2026 · Reading time: 13 min · Written by the ETpower engineering team (Taizhou XuLi Machinery Co., Ltd.)
"It is all concrete" is the sentence that costs contractors and distributors the most money. In our test bay in Taizhou, and in the feedback we get from distributors in Eastern Europe, the Middle East, South Asia and South America, the same three complaints come back again and again: fixings pulling out of blockwork, holes blowing out the back of a brick wall, and a machine that feels underpowered on a poured slab. Nine times out of ten the machine is not the problem. It was sized by hole diameter, when it should have been sized by base material.
That distinction matters because the three common substrates behave nothing alike. A hollow concrete block is mostly air, held together by thin webs. A perforated clay brick is hard and brittle, again full of voids. Poured structural concrete is dense, abrasive, usually reinforced, and the only one of the three that genuinely rewards a heavy hammer mechanism. Drill all three with the same machine on the same setting and you will get three different kinds of bad hole.
This guide is written the way we size machines for customers: start from the material, then the hole range, then the duty cycle. If you want the broader selection logic first, our SDS-Plus rotary hammer selection guide covers the full decision tree; this article goes deeper on the one variable that guide can only summarise — what you are actually drilling into.
Quick answer (TL;DR)
- Size by material first, diameter second. Hollow block, perforated brick and poured concrete punish different mistakes.
- Hollow block: turn the hammer off. Rotary-only, light feed pressure, and accept that the fixing must suit a hollow substrate.
- Perforated brick: rotary-only for the first pass, low impact if the wall is solid. Expect blow-out at the back face and plan the fixing around it.
- Poured concrete is what impact energy is for. A 26 mm class machine around 3.0 J covers most fixing work; 28 mm only if the holes are big and the duty is heavy.
- Bit geometry follows the material. Two-cutter for speed in solid concrete, four-cutter for survival in brick and block.
- Stock by local construction practice, not by catalogue order. Block-dominant markets and cast-concrete-dominant markets need different size mixes.
1. Why the base material matters more than the hole diameter
A catalogue tells you a 26 mm rotary hammer drills holes up to 26 mm. That number is a mechanical limit, not a recommendation. What actually determines whether the machine is right is the combination of three things: how hard the material is, how much of it is there, and what happens to the hole when you get to the other side.
Impact energy — the joule figure on the spec sheet — is the number people shop by, and it is genuinely useful, but only in context. Impact energy is what breaks the material at the cutting edge. If the material is soft and full of voids, energy you put in does not get converted into cutting; it gets converted into breaking webs, spalling faces and enlarging the hole. Every joule beyond what the material needs makes the hole worse, not faster.
This is why a small machine can outperform a big one on blockwork. A 20 mm class tool at around 1.7 J, used in rotary-only mode, will produce a clean parallel hole through a hollow block that a 28 mm machine at 3.2 J will turn into a crater. The bigger tool is not worse; it is simply applying a mechanism the material does not want.
The practical consequence for anyone specifying tools is simple: write down the substrate before you write down the hole size. On a mixed site — blockwork partitions, brick façade, cast concrete structure — the honest answer is often two machines rather than one compromise, which is also the conclusion our 20mm vs 26mm comparison reaches from the sizing side.
2. The three base materials side by side
Here is the comparison we use when a distributor sends us a market brief. The columns that matter are the last three: what goes wrong, what mode to use, and what class of machine suits it.
| Base material | What it is really like | Typical hole range | Usual failure mode | Mode that works | Sensible machine class |
|---|---|---|---|---|---|
| Hollow concrete block | Lightweight, 25–40 mm webs, large voids, low strength | 6–20 mm fixings | Hammer action breaks the web and the far face; anchor expands into a void | Rotary-only, light feed | 20 mm class, or hammer drill |
| Perforated clay brick | Hard and brittle, 15–30% voids, breaks out at the back | 6–16 mm fixings | Bit wanders between webs, back face spalls, plug anchor has nothing to grip | Rotary-only first pass; low impact on solid brick | 20 mm class; 26 mm for solid brick |
| Solid / engineering brick | Dense fired clay, no voids, abrasive | 6–20 mm | Bit glazes and overheats if feed pressure is too low | Hammer, moderate | 26 mm class |
| Poured / cast-in-place concrete | Dense, 20–40 MPa typical, usually reinforced, highly abrasive | 8–28 mm | Bit wanders on aggregate, hits rebar, hole oversizes | Full hammer | 26 mm class; 28 mm for heavy duty |
| Aerated concrete (AAC) | Very light, soft, no coarse aggregate | 6–12 mm | Hammer action oversizes the hole badly | Rotary-only | Any; low energy essential |
Two rows in that table surprise people. Aerated concrete — the white lightweight block used across a lot of Eastern European and South Asian residential work — is the one material where a rotary hammer is actively the wrong tool, and yet it gets bought for it constantly because the wall is "concrete". And solid engineering brick sits closer to cast concrete than to perforated brick, which is why lumping "brick" into one buying decision never works.
3. Hollow block: light impact, and often none at all
A standard hollow concrete block has faces and webs of roughly 25 to 40 mm, with voids that can be 50 mm or more deep behind them. Drill into one with full hammer action and the sequence is predictable: the bit cuts the near face cleanly, drops into the void, and then the hammer mechanism — which is still delivering thousands of blows a minute — starts breaking the far web as the bit reaches it. You get a hole with a crater on the inside face and a bell-mouthed entry.
An expansion anchor in that hole expands into air. A nylon plug grips the near face only. Both will hold a towel rail and neither will hold a handrail, and the difference is not the anchor's fault.
The fix is procedural rather than mechanical:
- Switch to rotary-only. Every SDS-Plus rotary hammer we build has a rotation-stop position on the mode dial for chiselling; the third position — rotary drilling without hammer — is the one people forget exists. On blockwork it is the correct setting.
- Reduce feed pressure. Let the bit cut. Leaning on the machine in a hollow substrate is what breaks the far web.
- Choose the fixing for a hollow substrate. Injection anchors with a mesh sleeve, or through-fixings with a rear plate, are designed for exactly this. Standard expansion anchors are not, and no amount of drilling technique changes that.
- Expect a shorter bit life in abrasive block. Some lightweight aggregates are far more abrasive than their compressive strength suggests, and the bit tip will show it.
One honest note: for a crew that works almost entirely in hollow block and aerated concrete, a rotary hammer is more machine than the job needs. A decent hammer drill in rotary mode will do the work at a lower purchase price. We say so rather than sell into it — the right answer for that customer is a hammer drill plus one SDS-Plus machine for the occasional structural concrete, which is precisely the split our rotary hammer vs hammer drill breakdown lays out.
4. Perforated brick: the blow-out problem
Perforated clay brick is the most misunderstood substrate on this list. It is hard — often harder than the concrete poured next to it — and at the same time it is 15 to 30% holes. That combination produces two distinct problems and they need different answers.
The first is blow-out at the back face. The bit exits a web into a void, then hits the back face and spalls a cone of material off the inside of the wall. On a rendered or plastered wall this shows as a star crack on the far side. In rotary-only mode with a sharp bit and moderate feed, the back face is cut rather than broken and the blow-out largely disappears. It is the single biggest quality improvement available on brick, and it costs nothing.
The second is wandering. A bit crossing voids has nothing to guide it, so it drifts — and because the voids are irregular, the drift is not predictable. This is the same physics behind the problem we cover in our guide to why a bit wanders in concrete, made worse because there is no material on one side of the flutes for half the hole. Drilling a pilot hole, keeping the bit short, and accepting that a 6 mm pilot before the final size will track better are all worth the extra thirty seconds.
Then there is the fixing question, which is where specifications usually go wrong. Perforated brick is a hollow substrate for anchoring purposes even though it feels solid when you drill it. The answer is the same as for blockwork: sleeve or injection anchors for anything load-bearing, and an honest load rating for anything else.
One more thing that catches people out: some clay bricks are extremely abrasive, and a bit that has been hammering into them will glaze. Glazing shows as a polished tip and a sudden drop in drilling speed, and the cure is a new bit, not more feed pressure. Pushing harder on a glazed bit overheats the tip and shortens its life further.
5. Poured concrete: where impact energy earns its keep
This is the substrate the rotary hammer was invented for. Cast-in-place structural concrete is dense, abrasive, contains hard aggregate, and is usually reinforced. There is nothing to break out and no void to lose the anchor into. Here, impact energy converts directly into penetration rate, and a bigger mechanism is genuinely faster.
The reference we test against in Taizhou is around 30 MPa, which sits in the middle of the 20–40 MPa band typical of structural work. On that material, with a sharp bit and a correctly set clutch, a 26 mm class machine at roughly 3.0 J is the sweet spot for the fixing work that makes up most of a day: 8 to 20 mm holes for anchors, brackets, conduit and services.
Three things change the answer, and all three push upwards:
- Hole diameter. Above about 20 mm the work per blow rises sharply. A 26 mm machine will drill a 24 mm hole; it will not do it happily all day.
- Hard aggregate. Granite and basalt aggregate are dramatically slower than limestone. In some regional mixes the practical drilling rate halves, and the extra energy of a 28 mm class machine is the difference between a two-minute hole and a five-minute one.
- Duty cycle. Occasional fixing holes and production drilling are different jobs. If the machine is running for hours rather than minutes, the larger class runs cooler and lasts longer.
Reinforcement is the fourth variable and it is not about power at all. Hitting rebar is a locating problem, not a power problem — and a more powerful machine makes it worse rather than better, because it will happily drill through a bar and leave you with a compromised structural element and a ruined bit. Our guide to drilling reinforced concrete without hitting rebar covers the scanning and permit side, and it is worth reading before the machine choice, not after.
6. Matching the machine class to the material
Put the two together and the selection becomes a short exercise. This is the mapping we give distributors when they are building a range for a specific market.
| Machine class | Typical impact energy | Best on | Acceptable on | Wrong for |
|---|---|---|---|---|
| 20 mm class (e.g. ETRH2-20) | ~1.7 J | Hollow block, AAC, perforated brick in rotary-only, 6–12 mm fixings, overhead and confined work | Occasional 10–16 mm holes in soft poured concrete | Production drilling in 30 MPa concrete, holes above 16 mm, chiselling duty |
| 26 mm class (e.g. ETRH2-26) | ~3.0 J | Poured concrete 8–22 mm, solid brick, general site fixing, mixed-trade fleets | Block and perforated brick with the hammer off; light chiselling | All-day 26 mm coring; heavy demolition chiselling |
| 28 mm class (e.g. ETRH2-28) | ~3.2 J | Production drilling 20–28 mm, hard aggregate concrete, combined drill-and-chisel crews | Everything the 26 mm does, at a weight and cost penalty | Fine overhead fixing work; crews who mainly work block and brick |
Read the "wrong for" column before ordering. It is the column that stops a distributor ending up with a warehouse full of the size that sells easiest rather than the size the market drills into. And note what the 20 mm row says about overhead work: on a ceiling, in a service void, or anywhere the operator is working one-handed above shoulder height, the lighter machine is the faster machine regardless of what is being drilled, because the limiting factor becomes the operator rather than the material.
The honest ceiling on this range: our current ETpower rotary hammer range covers SDS-Plus machines in 20, 26 and 28 mm classes. That covers the overwhelming majority of fixing and service drilling. It does not cover large-diameter coring above roughly 32 mm, or heavy breaker work, which belongs to the SDS-Max class. We do not currently build SDS-Max machines. If your market needs them, talk to us about the development route rather than expecting a product page that does not exist — our SDS-Max vs SDS-Plus guide explains where that line falls, and our engineering team can be reached through the contact page.
7. Bits and modes that change with the base material
The machine is half the decision. The bit and the mode dial are the other half, and they are where most of the quality difference actually lives.
| Choice | Hollow block / AAC | Perforated brick | Solid brick | Poured concrete |
|---|---|---|---|---|
| Mode | Rotary-only | Rotary-only, then low hammer if solid | Hammer | Full hammer |
| Cutter count | 4-cutter, survives voids | 4-cutter, resists break-through | 2-cutter | 2-cutter for speed; 4-cutter for hole quality |
| Feed pressure | Light, let it cut | Light to moderate | Firm enough to keep cutting | Firm, steady, back off on rebar |
| Pilot hole | Not usually needed | Yes, 6 mm first | Helpful above 16 mm | Yes above 20 mm |
| What kills the bit | Abrasive lightweight aggregate | Glazing on hard clay | Heat from low feed | Rebar strikes, dust packing |
| Dust control | Lower silica risk, still control it | Silica present — extract | Silica present — extract | Highest silica risk — M-class extraction |
That last row is the one that gets skipped, and it is worth being blunt about it. Clay brick and concrete both contain respirable crystalline silica, and the dust from drilling either is a serious long-term health hazard, not a housekeeping issue. The material does not change the requirement: it changes how much dust you make. Our dust extraction guide covers the shroud and vacuum classes, and the exposure limits quoted there apply to brick dust as much as to concrete dust.
And one mode caution that belongs in every material conversation: never run rotation-stop with a drill bit fitted. Chisel mode exists so a chisel can be oriented by hand; using it with a drill bit rounds the shank grooves in an afternoon and takes the chuck with it. If that has already happened, the diagnosis sequence in our guide to a wobbling SDS-Plus chuck will tell you which part to order.
8. What distributors get wrong when stocking one size per market
We ship to more than forty markets and the pattern is consistent. A distributor builds a range around the size that sells most easily — usually the mid-size, because it is the defensible compromise — and then discovers that the local construction method makes one of the other classes the volume seller.
A few concrete examples of how the material decides the mix:
- Block-dominant residential markets. Where infill walls are hollow block or AAC, the volume is light fixings and the 20 mm class outsells everything else by a wide margin — but only if somebody tells the buyer to switch the hammer off. Without that conversation, the returns come back as "not powerful enough", which is a settings complaint dressed as a spec complaint.
- Cast-in-place structural markets. Where buildings are framed in reinforced concrete, 26 mm is the volume class and 28 mm is the professional tier. Block still exists for partitions, so a token 20 mm SKU makes the range complete rather than profitable.
- Clay-brick heritage and façade markets. Solid brick behaves like concrete and perforated brick behaves like block, often within the same building. The machine answer is 26 mm with a strong emphasis on bit and mode training.
The commercial point: the right range is not three sizes in equal quantities. It is a material-weighted mix, and the weighting should come from what gets built locally, not from what the catalogue lists first. That is also why we ask about construction practice in our OEM sourcing conversations before we quote a model mix — the answer changes the container, not just the conversation.
9. FAQ
Can I drill hollow concrete block with a rotary hammer?
Yes, but you usually should not use hammer action. A hollow block has thin webs of maybe 25 to 40 mm and large voids behind them; hammering blows out the far face and leaves a ragged hole that no expansion anchor will grip properly. Use rotary-only mode with a sharp multi-purpose bit, or a hammer drill on its rotary setting. Save the hammer action for the solid concrete sections.
Which rotary hammer size suits perforated clay brick?
A light 20 mm class machine around 1.5 to 2.0 J is the right starting point, again in rotary-only mode for the first pass. Perforated brick is hard but full of voids, so the bit breaks through into air repeatedly and wanders. If the wall is solid engineering brick or the holes need to hold structural anchors, step up to a 26 mm class machine and drill with hammer action on a low setting.
Do I need a 28 mm rotary hammer for poured concrete?
Only if the work is repetitive and the holes are large. For occasional fixing holes up to about 16 mm in 25 to 35 MPa concrete, a 26 mm class machine at around 3.0 J is faster to handle and less tiring. The 28 mm class earns its place when you are drilling 20 to 28 mm holes all day, working in hard aggregate, or chiselling as well as drilling.
Why do my anchors pull out of blockwork?
Because the hole was drilled with hammer action and the void behind the web was broken open, so the anchor is expanding into a cavity instead of into material. Either switch to rotary-only and accept a lower load rating, or use a fixing designed for hollow substrates such as an injection anchor with a mesh sleeve or a through-bolt with a wide rear plate.
Does the base material change which drill bit I should use?
Yes, mainly in cutter count and tip geometry. A two-cutter bit clears dust faster and drills quicker in solid concrete. A four-cutter bit is more robust when it is repeatedly breaking through webs and voids, which is exactly what happens in perforated brick and hollow block, so it survives longer even though it cuts slightly slower.
10. Conclusion
The question to ask before "how big is the hole" is "what is behind the surface". Hollow block wants rotary-only and a fixing designed for voids. Perforated brick wants rotary-only, a pilot hole and realistic load ratings. Poured concrete is the one substrate where impact energy pays for itself, and where stepping up in class buys real speed.
Get the material right and the machine size mostly takes care of itself: 20 mm class for block and light fixings, 26 mm class for the bulk of concrete work, 28 mm class when the holes are large, the aggregate is hard or the duty is continuous. Get it wrong and no amount of joules will give you a hole an anchor will hold.
Not sure which mix suits your market? Tell us what your customers build with — block, brick or cast concrete — and we will propose a size mix and a bit package to match. You can also browse the full ETpower rotary hammer range, the 20mm sub-category for block and light fixing work, and the 26mm sub-category for general concrete duty. Our company profile explains how we build and test in Taizhou.
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This article is maintained by the ETpower engineering team. Last reviewed on 26 October 2026. Density, strength, web thickness and hole-range figures are typical values drawn from common construction materials and our own test work in Taizhou, and will vary with local standards, aggregate type, block design and mix design. Drilling rates depend on bit condition, feed pressure and reinforcement. Silica exposure limits are a matter of local regulation — always apply the current requirement in your jurisdiction. Our current SDS-Plus range covers 20, 26 and 28 mm classes; larger SDS-Max applications are outside it and should be discussed with us directly.
