Craft Quantities
Plan & Takeoffs

Cross-market term

Concrete block

The precast unit a masonry wall is built from, larger than a brick and laid in the same bedded courses. Markets divide them by what they are made of, how dense they are, and — in two cases — by a word that no longer describes the material.
  • 4Markets
  • NoSame thing everywhere
  • 3Calculators

What it is called, by market

One concept, four markets. Where a name means something else locally, the card says so rather than leaving you to find out on site.

  • United Kingdom

    Same word, different thing

    concrete block

    also breeze block, blockwork, aerated block, dense block

    Breeze originally meant coke breeze, the fuel ash the block was made with. Almost no block sold today contains any, and the word now loosely covers lightweight aggregate and aerated blocks that are chemically unrelated.

  • Australia

    Same word, different thing

    concrete block

    also besser block, blockwork, masonry block

    Besser is a manufacturer's name used generically, in the same way Hoover or Biro are — so a specification saying besser block has named a shape and a tradition rather than a product.

  • United Statesyours

    Same word, different thing

    CMU

    also concrete masonry unit, cinder block, breeze block, block

    Cinder block carries the same history as breeze and the same inaccuracy. And in American usage BREEZE BLOCK means the decorative perforated screen block, which is a different product entirely.

  • Canada

    Close, not identical

    CMU

    also concrete block, cinder block, block

    As the United States under CSA rather than ASTM, with the same cinder-block inaccuracy in everyday speech.

The governing standard, by market

  • United Kingdom

    BS EN 771-3 / BS EN 772-1

    Specification for aggregate concrete masonry units, and the determination of compressive strength.

  • United States

    ASTM C90 / TMS 402

    Loadbearing concrete masonry units, and the design of masonry structures.

Calculators for this

Each works in either measurement system, and the terminology on the page follows whichever market you have selected.

Retaining Wall Block Calculator →CMU Wall Self-Weight Calculator →Concrete CMU Block Counter & Grout Infill Calculator →

Frequently asked questions

Is a breeze block the same as a cinder block?
Historically they were close cousins and today neither word describes what is in the bag. Both named a block made with the ash left over from burning fuel — coke breeze in Britain, coal cinders in the United States — which was cheap, plentiful and light. That material is essentially gone from block production, and what a merchant sells under either name today is made with a lightweight aggregate, a dense aggregate, or is an autoclaved aerated block, which is a completely different material made by expanding a cement slurry with aluminium powder. The practical consequence is that the word tells you nothing about the two properties that matter — density and compressive strength — and both are printed on the block or its documentation.
Why does block density matter so much?
Because it decides four different things at once and they pull against each other. A DENSE block carries more load, so it goes where the structure needs it; it also conducts heat readily, weighs a great deal to lift, and holds a fixing well. A LIGHTWEIGHT or aerated block insulates far better and can be cut with a hand saw, but carries less, and a heavy fixing into it needs a specific anchor rather than a normal plug — a kitchen cupboard pulling out of an aerated block wall is one of the commonest failures in a converted room. Sound is a fifth axis pulling the other way from insulation: mass blocks sound, so the lightweight block that keeps heat in lets noise through. A specification that names only the size has not specified the block.
What does a breeze block mean in American usage?
The decorative screen block, which is not a structural unit at all. Mid-century American and Australian architecture used perforated concrete blocks to build screen walls that admit light and air while giving privacy, and those are what a US supplier means by breeze block — the name comes from the breeze passing through them. They are ornamental, they are laid in a stack bond with reinforcement in the joints, and they are not interchangeable with anything a British specification means by the term. Somebody ordering breeze blocks across markets can quite easily receive a pallet of perforated screen units for a load-bearing inner leaf.