Ask ten Aussie builders the difference between besser block and concrete block and you’ll get ten slightly different answers. The truth is simpler than the jargon makes it sound, and getting it right matters because the wrong block type adds weight, slows the build, and can leave you short on structural capacity when the engineer’s drawing lands.

This guide breaks down what besser block and solid concrete block actually are, the Australian standards behind them, the sizes you’ll see at the supplier, real 2026 prices, core fill rules, reinforcement, and the practical decision tree for choosing one over the other on the job. If you just want the numbers, jump straight to our Concrete Block Calculator and Block Fill Calculator — both are free, no signup.

Quick comparison: besser block vs solid concrete block

Before we dig in, here’s the head-to-head. Numbers are for the most common Australian residential and light commercial sizes in 2026.

Prices are 2026 metro Australia, ex-GST, ex-supplier — not including mortar, reo, core fill or labour. Add ~30 – 40% for regional and remote.

What “besser block” actually means

Here’s the thing most articles skip: besser is a brand name, not a product category. The Besser Company is an American manufacturer of block-making machines, and Australian masonry suppliers started using the name “besser” generically the same way Aussies say “Esky” for any cooler. What you’re actually buying is a concrete masonry unit (CMU) — specifically the hollow variety.

Across Australia you’ll see the same block under different brands:

• Boral Masonry — “GB Series” hollow blocks
• Adbri Masonry (Adelaide Brighton group) — standard hollow block range
• Austral Masonry — “Masonry Block” range
• Brickworks / Austral Bricks in NSW/QLD
• Smaller state players in WA (Midland Brick), SA (Rocla), TAS

The block is functionally the same regardless of brand because they all have to comply with the same Australian Standard.

The Australian Standard: AS 4456

Every concrete masonry unit sold in Australia — besser, solid, decorative, split-face, you name it — is tested to AS 4456 (Masonry units, segmental pavers and flags — Methods of test). This standard covers:

• Compressive strength (the block’s load capacity, expressed in MPa).
• Dimensional tolerances (length, height, width — how square the block is).
• Water absorption and density.
• Salt attack resistance (critical for coastal and reactive-soil sites).
• Efflorescence rating.

Once those blocks land on site, they get laid to a different standard: AS 3700 (Masonry Structures). AS 3700 is the bible for mortar mix, reinforcement, core fill, control joints, and wall design. If your engineer’s drawing references “AS 3700 compliant,” that’s the standard they’re pointing at.

Don’t take a tradie’s word for compliance — ask the supplier for the AS 4456 test certificate on bulk orders, especially for engineer-designed walls. Reputable suppliers will hand it over without flinching.

Standard sizes you’ll see in 2026

Australian concrete blocks are sized to a 200 mm work unit — meaning a 190 mm block plus a 10 mm mortar joint equals exactly 200 mm. That’s why drawings dimension in 200 mm increments.

Hollow besser block sizes (work face 390 × 190 mm)

• 190 series: 390 × 190 × 190 mm — the workhorse. Used for foundations, retaining, perimeter, loadbearing walls.
• 140 series: 390 × 190 × 140 mm — lighter cavity walls, internal loadbearing.
• 110 series: 390 × 190 × 110 mm — non-loadbearing partitions where you still want core fill.
• 290 series: 290 × 190 × 190 mm — half-block / quoin block for ends, corners and step-downs.

Solid block sizes

• 90 mm solid: 390 × 190 × 90 mm — common for veneer skins, fire-rated partitions.
• 140 mm solid: 390 × 190 × 140 mm — non-loadbearing internal walls with high acoustic spec.
• 190 mm solid: 390 × 190 × 190 mm — thermal mass walls, fire walls, dense acoustic walls.

Working out exact counts for your wall is where most builders waste a Sunday on a calculator. Run the dimensions through our free Concrete Block Calculator instead — it factors in mortar joints, openings and a wastage buffer.

Hollow besser vs solid concrete: the real differences

Weight and handling

A 190 series hollow besser weighs around 15 kg. A solid 190 mm block can hit 30 kg. Over a long day, that’s the difference between a bricklayer comfortably laying 200 – 250 blocks and a sore back at 150. On big walls, solid block almost always needs lifting aids or a second labourer just to keep the courses moving.

Density and thermal mass

Solid block wins on raw thermal mass — the dense concrete absorbs heat during the day and releases it overnight, which is genuinely useful in passive solar designs. A hollow besser with core fill closes most of the gap, but an uncored hollow wall is poor at thermal regulation. If you’re chasing a NatHERS star rating, this matters.

Acoustic performance

For sound, mass wins. Solid 190 mm walls hit Rw 55 – 58 dB without much effort. Core-filled hollow gets to Rw 50 – 52 dB. Empty hollow drops to Rw 42 – 45 dB. That’s why party walls in townhouses and apartments often spec solid or fully core-filled hollow block, not bare hollow.

Structural capacity

This is where hollow besser pulls ahead for most jobs. The cores let you run vertical N12 or N16 reo up through the wall, tie it into the footing’s starter bars, and then pump the cores full of concrete. The result is essentially a reinforced concrete wall with a masonry face — capable of resisting massive bending loads from retained soil, water pressure or wind. Solid block can’t do this without external piers or buttresses.

Core filling: when, how much, and how

If you take one thing from this guide, take this: core fill is what makes a besser block wall structural. Skip it on a wall the engineer specified to be filled, and you’ve built a stack of fragile bricks.

When core fill is mandatory

• Retaining walls over 600 mm tall (most councils).
• Loadbearing walls carrying floor or roof structure.
• Basement and below-ground walls (always).
• Pool surround walls and walls within the engineer’s wind zone.
• Boundary walls over a certain height (varies by council, usually 1.8 m).
• Anywhere vertical reinforcement is specified on the engineer’s drawing.

How much concrete you’ll need

A 200 series block has two cores, each roughly 110 mm x 150 mm x 190 mm. That’s about 0.013 m³ of fill per block, or:

• ~13 litres of core fill per block (when fully filled both cores).
• ~0.015 m³ per m² of wall, allowing for 10% slop and waste.
• For a 10 m long, 2 m high, fully cored wall: ~3.0 m³ of pump-mix concrete plus the strip footing.

This is exactly what our Concrete Block Fill Calculator works out for you in two clicks — punch in wall dimensions, the block series, and whether you’re filling every core or every second core. It returns the m³ of concrete to order so you don’t get caught short mid-pour.

Fill mix specification

Core fill isn’t normal structural concrete — the aggregate has to be small enough to flow through the cores. Standard spec:

• Strength: N20 minimum, N25 typical (matching footing strength).
• Maximum aggregate size: 10 mm (not 20 mm).
• Slump: 200 – 240 mm — high-slump pump mix, often with superplasticiser.
• Placement: Pumped or rodded into the cores in lifts no taller than 1.5 m to prevent segregation. Vibrate or rod between lifts.

Reinforcement and mortar mix

Standard residential and light commercial besser blockwork uses:

• Vertical reo: N12 or N16 bars in the core at engineer-specified centres (typically 400 mm or 600 mm), lapped 600 mm minimum into footing starter bars.
• Horizontal reo (bed joint reo): Galvanised ladder mesh in every second or third bed joint, especially in long walls and around openings.
• Mortar: M3 mix is standard residential — 1 part cement : 1 part lime : 6 parts sand, with mortar plasticiser. M4 (1 : 0.5 : 4.5) for higher-strength or marine zones.
• Control joints: Every 6 m on long walls and at openings, to control thermal and shrinkage cracking.

None of this is optional — the engineer’s drawing will spell it out, and the building surveyor will inspect it before pouring core fill. Tell the bricklayer up-front whose reo schedule they’re working to.

Real applications: when to pick which

Use hollow besser block when…

• You’re building a retaining wall over 600 mm tall.
• The wall is a foundation, basement or below-ground wall.
• The wall is loadbearing and carries reo through the cores.
• You need a fast, light, mortar-economical external perimeter wall.
• The engineer has specified vertical N12/N16 reo at centres.
• Cost is a primary driver and the wall doesn’t need solid thermal/acoustic mass.

Use solid concrete block when…

• You need maximum acoustic separation (apartment party walls, recording studios).
• The wall is a fire-rated separation with a long FRL (Fire Resistance Level) requirement.
• You’re after passive solar thermal mass in a heated/cooled space.
• The wall is non-loadbearing and doesn’t need internal reo — partitions, internal accents.
• Aesthetic finish (split-face, polished, coloured solid block) is a feature.

Aesthetic vs structural: the finish decision

Plenty of Aussie homes show off raw masonry as a design feature now — off-form besser, split-face solid block, and honed coloured concrete are all back in fashion. Here’s the practical split:

• Raw face besser: Industrial, cost-effective, common in coastal modernist homes. Needs a quality bricklayer to keep joints tight and consistent.
• Rendered besser: The default suburban finish — 2-coat acrylic over fibreglass mesh hides imperfections and lets you colour-match anything.
• Split-face solid block: Premium finish with a stone-like texture. Cost is 50 – 80% higher than raw besser but it stays the finished face forever.
• Honed and polished solid: Smooth, dense, often used internally as a feature wall. Specialist supply only, lead times 4 – 6 weeks.

Important rule: aesthetic blocks don’t always come in structural strength grades. If you’re using a split-face or coloured block for a loadbearing wall, double-check the AS 4456 compressive strength rating — some decorative ranges only test to 10 MPa which limits your wall height and engineering options.

Cost comparison: per block and per m² (2026 Australian metro)

Installed pricing includes mortar, bricklayer labour and standard reo, but not core fill, render, or footings. Add roughly $40 – $70/m² if the wall is fully core-filled. See our Concrete Cost Calculator for footing pricing.

Frequently asked questions

Is besser block the same as concrete block?

Yes and no. “Besser block” is an everyday Australian term for a hollow concrete masonry block — “Besser” being a brand of block-making machinery. Solid concrete block is a different product in the same family — same materials, no cores. Both comply with AS 4456 and are laid to AS 3700.

What size is a standard besser block in Australia?

The most common is the 200 series: 390 mm long × 190 mm high × 190 mm wide, with a 10 mm mortar joint giving a finished 200 mm work unit. Half-blocks (290 mm long) and 140/110 series narrower blocks are also widely stocked.

Do besser block walls always need to be core-filled?

No, but most loadbearing or retaining walls do. Garden screen walls under 600 mm tall and short non-loadbearing infill walls can stay unfilled. Anything over 600 mm tall, anything retaining soil, and anything supporting a structural load must be core-filled to the engineer’s specification — usually every core or every second core with N12/N16 reo.

How much concrete do I need to fill besser block?

Roughly 13 litres (0.013 m³) per fully filled 200 series block, or about 0.015 m³ per square metre of wall including waste. For exact volumes use the Block Fill Calculator — it accounts for partial fills (every second core) and pump waste.

Which is stronger: solid concrete block or hollow besser?

A bare solid block has higher compressive strength than a bare hollow block. But once you core-fill a hollow besser with N20 concrete and N12 vertical reo, the composite section is far stronger in bending than a solid block of the same dimensions. That’s why retaining and basement walls are nearly always built in hollow besser, not solid.

Can I build a retaining wall with solid concrete block?

Generally no, not for walls over about 600 mm. Solid blocks have no cores for vertical reo, so they can’t resist the bending forces from retained soil without expensive external reinforcement (piers, buttresses or a tied-in reinforced concrete spine). Hollow besser with core fill is the right choice for almost every Australian residential retaining wall.

Built for Aussie builders

Built Simple is Australian construction project management software made for small and medium builders, tradies, concreters and owner-builders. The Concrete Block Calculator currently ranks #1 for “besser block calculator” in Australia — pair it with the Block Fill Calculator and Concrete Cost Calculator for a full materials estimate in minutes. If blockwork is part of your weekly mix, see how we help concreters quote, schedule and track jobs without the admin headache.

Looking for related guides? See our 2026 retaining wall cost guide for installed pricing across timber, besser block and poured concrete walls.

Calum Buchanan is the founder of Built Simple, based in Melbourne. Built Simple was founded in August 2025 to give Australian builders simple, mobile-first project management software. Pricing and standards in this guide reflect 2026 Australian metro rates and AS 4456 / AS 3700 requirements; always confirm scope and engineering with a licensed structural engineer for your specific site.