TL;DR: besser block vs concrete block in 90 seconds. "Besser block" is a brand name that became the everyday Aussie term for a hollow concrete masonry block. Boral, Adbri and Austral all make the same product under different names. Hollow concrete block (besser): lighter, faster to lay, designed to be core-filled with concrete and steel reo. Standard size 390 × 190 × 190 mm. Solid concrete block: heavier, denser, better thermal mass and acoustic performance, no core fill needed but no room for vertical reo either. Use hollow besser for retaining walls, foundation walls, perimeter walls and basements where you need vertical reo plus core fill. Use solid concrete block for non-loadbearing partitions, fire walls, acoustic walls, or where thermal mass is a design feature. Both must be tested to AS 4456 and laid to AS 3700.

Ask ten Aussie builders to explain besser block vs 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. 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, mortar classes, and the practical decision tree for choosing one over the other on the job. There's also a short FAQ at the end covering the questions we hear most from builders and owner-builders.

If you just want the numbers, jump straight to the Concrete Block Calculator and Block Fill Calculator in the free Built Simple app. Both work out counts and fill volumes with mortar joints and wastage included, no signup needed.

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.

Property	Besser block (hollow)	Solid concrete block
Standard size	390 × 190 × 190 mm	390 × 190 × 90/140/190 mm
Weight (per block)	~14 – 17 kg	~22 – 32 kg
Density	~1,400 – 1,700 kg/m³	~2,100 – 2,400 kg/m³
Cores for reo + fill?	Yes (two cores per block)	No
Cost (per block, 2026)	~$3.80 – $5.50	~$5.50 – $8.50
Cost (per m² wall area)	~$50 – $75 (block only)	~$75 – $115 (block only)
Thermal mass	Moderate (better when core-filled)	High
Acoustic Rw	~45 – 52 dB (filled)	~50 – 58 dB
Best uses	Retaining walls, foundations, basements, loadbearing perimeter walls	Fire walls, party walls, acoustic walls, non-loadbearing partitions

Prices are 2026 metro Australia, ex-GST, ex-supplier. They don't include mortar, reo, core fill or labour. Add roughly 30 to 40% for regional and remote areas, where freight on heavy masonry bites hard.

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 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 and QLD
• Smaller state players in WA (Midland Brick), SA and TAS

The block is functionally the same regardless of brand because every one of them has to comply with the same Australian Standard. So when your supplier quotes "grey block" and your engineer's drawing says "CMU" and the labourer calls it a besser, relax. It's all the same unit.

For a full run-through of every series, shape and special block on the Australian market, see our Besser Blocks: Sizes, Types, and Australian Standards Guide.

The standards: AS 4456, AS 3700 and the NCC

Every concrete masonry unit sold in Australia, besser, solid, decorative, split-face, the lot, 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, how square and true the block is
• Water absorption and density
• Salt attack resistance, critical for coastal and reactive-soil sites
• Efflorescence rating, the white bloom that ruins face-block finishes

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. It's one of the standards the National Construction Code references for masonry construction, so "AS 3700 compliant" on your engineer's drawing isn't a suggestion. It's the compliance pathway for the whole wall.

Two practical points that flow from this:

1. Ask for the test certificate. 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 hand it over without flinching.
2. Mortar class matters. AS 3700 sets out mortar classes, and the common call-outs are M3 for general above-ground work and M4 for below ground, in contact with soil, or within reach of salt spray. If your job is a retaining wall or a coastal fence, check the drawing before the sand and cement get mixed. The wrong mortar class in an aggressive environment is a durability defect waiting to be found at handover.

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 walls in 200 mm increments, and why an odd wall length means cut blocks, extra labour and extra waste.

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

• 190 series: 390 × 190 × 190 mm, the workhorse. Foundations, retaining, perimeter and loadbearing walls.
• 140 series: 390 × 190 × 140 mm, lighter cavity walls and 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 and fire-rated partitions.
• 140 mm solid: 390 × 190 × 140 mm, non-loadbearing internal walls with a high acoustic spec.
• 190 mm solid: 390 × 190 × 190 mm, thermal mass walls, fire walls, dense acoustic walls.

One number worth memorising: at 390 × 190 with a 10 mm joint, you get 12.5 blocks per square metre of wall. That's straight arithmetic (each block plus joint covers 0.08 m²), and it holds for every series because the face size doesn't change. Working out exact counts, corners, openings and wastage for a whole job is where builders waste a Sunday. The Concrete Block Calculator in the free Built Simple app does it in under a minute.

Besser block vs concrete block: which one for which job

This is the decision that actually matters on site, so let's take it wall type by wall type.

Retaining walls: hollow besser, almost every time

A retaining wall is a structure resisting lateral soil pressure, so it needs vertical steel tied into a concrete footing, and the only block that accepts vertical reo is a hollow one. The cores line up vertically, the starter bars come up out of the footing, N12 or N16 bars are typical call-outs, and the cores get filled with concrete so the wall acts as one reinforced unit.

Keep in mind that most councils require engineering and approval for retaining walls above a certain height, commonly around 1 m but lower in some areas, so check before you dig. For block choice, drainage detail and the full build sequence, our Retaining Wall Blocks: Australian Builder's Guide covers it end to end.

Foundation walls and basements: hollow besser

Same logic as retaining walls. Below-ground walls cop lateral loads and need to tie into footings and slabs, which means reo and core fill. A 190 series hollow block, filled and reinforced to the engineer's drawing, is the standard Australian answer. Waterproofing and drainage behind the wall matter as much as the block itself, and that detail sits with the designer, not the supplier.

Loadbearing perimeter walls: hollow besser

For single and double storey masonry construction, hollow block with core fill at engineer-nominated centres gives you loadbearing capacity without laying a wall of 30 kg units. Your bricklayer's shoulders will thank you, and so will the day rate, because a lighter block lays faster.

Fire walls and party walls: solid block earns its keep

Solid blocks are dense, and density is what fire resistance levels and acoustic ratings reward. A solid 140 or 190 mm block wall achieves strong FRL and Rw numbers without core filling, which is why solid block turns up in duplex party walls, garage fire walls and plant room enclosures. Always match the specific block to the FRL on the drawing, because ratings are certified per product, not per category.

Acoustic walls: solid block, or filled hollow

Mass blocks sound. A solid block wall at roughly 2,100 to 2,400 kg/m³ outperforms an unfilled hollow wall easily, hitting Rw in the 50 to 58 dB range against about 45 to 52 dB for a filled hollow wall. If the job is a home theatre wall, a bedroom against a garage, or a unit party wall, solid block (or a filled hollow wall where you also need structure) is the right call.

Non-loadbearing partitions: either, decided by handling

For a simple internal partition with no structural role, a 90 mm solid or 110 series hollow both work. Solid gives better acoustics; hollow is lighter to lay and cheaper per square metre. On upper floors, check the slab's capacity before committing to solid, because the extra dead load is real.

Core fill and reinforcement: the part that trips people up

A hollow block wall is only half a structure until the cores are filled. A few rules of thumb, with the usual caveat that the engineer's drawing always governs:

• Core fill concrete is usually a 20 MPa mix with small aggregate, sold by batching plants as "block fill". The small stone matters because it has to flow down a 190 mm core past reo bars without honeycombing.
• Fill volume depends on the series and whether you're filling every core or only reinforced cores. Your supplier's technical data sheet lists litres per 100 blocks, or run the wall through the Block Fill Calculator in the Built Simple app and order once, not twice.
• Vertical reo sits in the cores at centres nominated by the engineer, lapped with starter bars from the footing. Horizontal reo goes in knock-out bond beam blocks, typically at the top course and at nominated intermediate courses.
• Clean-out openings at the base of reinforced cores let you confirm the fill reaches the bottom. Skipping them is a classic defect on inspected jobs.

Ordering the core fill is also where the budget wobbles, because block fill is priced like any other pre-mix and 2026 concrete prices vary a lot by state. Our state by state concrete cost breakdown has current per-m³ figures so you can price the fill line properly instead of guessing.

What it costs in 2026

Block-only prices in metro Australia currently run about $3.80 to $5.50 per hollow besser block and $5.50 to $8.50 per solid block, ex-GST. Per square metre of wall, that's roughly $50 to $75 for hollow and $75 to $115 for solid, before mortar, reo, core fill and labour.

Three cost notes worth building into your estimate:

1. Solid walls lay slower. A 22 to 32 kg unit against 14 to 17 kg changes a bricklayer's daily rate of progress, so the labour gap is bigger than the material gap suggests.
2. Hollow walls carry hidden lines. Core fill concrete, reo, bond beams and a pump for anything above a couple of courses. A "cheaper" hollow wall can land close to a solid wall once it's a structural, filled wall.
3. Freight is the regional killer. Blocks are heavy and cheap per unit, so cartage can add 30 to 40% outside the metros. Price delivery per thousand, not per block.

If you're quoting block work regularly, this is exactly the sort of assembly worth templating once and reusing. Our guide to the best construction estimating software in Australia covers how builders set that up.

The 30-second decision tree

• Does the wall retain soil or carry structure below ground? Hollow besser, reinforced and core-filled to the engineer's drawing.
• Is it loadbearing above ground? Hollow besser with core fill at nominated centres.
• Is it a fire or party wall with an FRL? Solid block matched to the certified rating.
• Is acoustics the priority and structure isn't? Solid block.
• Simple internal partition? Either. Pick by weight, price and what the slab can carry.
• Not sure? The engineer decides, not the supplier's counter staff.

Frequently asked questions

Is a besser block the same as a cinder block?
Near enough. "Cinder block" is the American term from the days when coal cinders were the aggregate. Modern Australian blocks use standard concrete aggregates, so "concrete masonry unit" is the accurate name and "besser" is the local nickname for the hollow version.

Do besser blocks always need core filling?
No. Only reinforced cores must be filled in a structural wall, at the centres the engineer nominates, plus bond beams. A non-loadbearing hollow partition can stay unfilled. Retaining and below-ground walls are typically fully filled.

How many besser blocks per square metre?
12.5, based on the 390 × 190 mm face plus a 10 mm mortar joint. Add wastage (5 to 10% is common) and count corner and half blocks separately.

Can I build a retaining wall from solid blocks?
Not a reinforced one, because there's nowhere for the vertical steel. Low garden edging is a different story, but anything structural needs hollow block, reo and core fill, or a purpose-made segmental retaining wall system.

Do I need an engineer for a block wall?
For retaining walls above your council's height threshold, anything loadbearing, and anything below ground, yes. For a low non-structural partition, generally no, but the NCC and your certifier have the final say.

Are prices GST inclusive?
The figures in this guide are ex-GST, which is how suppliers quote trade accounts. Add 10% for retail pricing, and remember GST applies to freight too.

Work it out before you order

The block choice comes down to one question: does the wall need steel in it? If yes, hollow besser. If the job is fire, sound or mass, solid. Everything else is detail, and the detail lives in AS 3700 and your engineer's drawings.

When you're ready to price the job, the free Built Simple app has the Concrete Block Calculator, Block Fill Calculator and 43 other trade calculators built for Australian jobs. Download it, punch in the wall, and order the right quantity the first time.