Cutting a brick with a bolster chisel and hammer is a traditional technique that bricklayers have relied on for generations — and with the right method, you can achieve a surprisingly clean break without any power tools. The key is patience: scoring all four faces of the brick before making your final split is what separates a clean cut from a ragged, crumbled mess.
What You'll Need
Before you start, gather the following:
- A bolster chisel (also called a brick bolster) — typically 75–100 mm wide
- A club hammer (lump hammer) — 1–1.5 kg is ideal
- Safety glasses — non-negotiable; brick chips fly unpredictably
- Leather gloves — to protect your hands from the chisel and sharp edges
- A pencil or chalk for marking
- A piece of timber or sand bed to rest the brick on
- A tape measure and combination square
You can find bolster chisels and club hammers at Bunnings or Mitre 10.
Safety First
Always wear safety glasses when cutting bricks. Brick fragments and dust can cause serious eye injury. A dust mask is also a good idea, particularly when working with older bricks that may contain silica dust — prolonged exposure to silica dust is a recognised health hazard. For guidance on managing dust risks on site, refer to WorkSafe NZ.
Step-by-Step: How to Cut a Brick with a Bolster and Hammer
1. Mark Your Cut Line
Use a pencil or chalk and a combination square to mark a clear line all the way around all four faces of the brick — the top, bottom, and both sides. Accuracy here matters; the chisel will follow your scored line.
2. Bed the Brick Properly
Place the brick on a firm but slightly forgiving surface. A piece of timber or a bed of sand works well — a hard concrete surface can cause the brick to shatter unevenly. The brick should feel stable and not rock.
3. Score All Four Faces
This is the most important step. Working around the brick methodically:
- Position the bolster chisel on your marked line, bevel facing the waste side of the cut
- Strike the chisel firmly with the club hammer — you're not trying to split it yet, just cutting a groove about 2–3 mm deep
- Rotate the brick and repeat on each face: top, both sides, and bottom
- Go around two or three times, deepening the groove with each pass
Taking your time here dramatically improves the quality of the final break.
4. Make the Final Split
Once you have a consistent groove around all four faces, position the brick so the top face is uppermost. Place the bolster chisel in the scored groove on the top face, hold it vertically, and deliver a single sharp, confident strike with the club hammer. In most cases, the brick will split cleanly along the scored line.
If it doesn't break on the first strike, rotate and strike the side faces before trying the top again — don't keep hammering the same spot or you risk shattering the brick.
5. Dress the Edge if Needed
The cut face may have small nibs or rough spots. You can knock these off gently with the corner of the bolster chisel or rub the face lightly on a piece of concrete or a rubbing stone to smooth it down.
Tips for a Cleaner Cut
| Tip | Why It Helps |
|---|---|
| Use a sharp bolster chisel | A blunt chisel crushes rather than scores |
| Score multiple passes | Deeper groove = cleaner break |
| Keep the chisel vertical | Angled strikes cause diagonal splits |
| Work on a sand or timber bed | Absorbs shock, reduces shattering |
| Cut the brick slightly oversize | You can always dress it back; you can't add material |
Understanding Brick Variation
Not all bricks cut the same way. Extruded (wire-cut) bricks — common in NZ — tend to split more predictably than pressed or handmade bricks, which can be denser and more unpredictable. Reclaimed bricks may also have hidden cracks or inconsistencies. If you're working with expensive or heritage bricks, consider hiring a bricklayer with an angle grinder and diamond blade for precision cuts.
For technical guidance on masonry construction in NZ, BRANZ is an excellent resource.
NZ Building Code Considerations
If your brickwork is part of a structural or weatherproofing element — for example, an exterior wall, a retaining wall, or a fireplace — it may require a building consent depending on the scope of work. Schedule 1 of the Building Act lists certain exemptions, but these have conditions. Always check with your local council before starting any structural masonry work. The MBIE Building Performance website has clear guidance on when consent is required.
When to Call a Professional
The bolster-and-hammer method is perfectly suited to occasional cuts on a small DIY project — a garden edging repair, a single course of brickwork, or a simple step. However, you should hire a qualified bricklayer if:
- You need many precise cuts (a power saw will save time and waste)
- The brickwork is structural or load-bearing
- You're working on a heritage or character property where matching the finish matters
- You're unsure about consent requirements
- The bricks are unusually hard, dense, or valuable
A skilled bricklayer will have the tools and experience to get the job done efficiently and to a professional standard. You can find qualified local bricklayers on tradedirectory.co.nz.
Licensed Building Practitioner (LBP)
