Concrete Blocks vs Breeze Blocks: Which Should You Buy?

Concrete blocks and breeze blocks are not the same thing. They do look similar and stack the same way, but in terms of performance, they differ heavily, and if you’re pricing up a project and don’t actually know the differences, stop and check what product you actually need.

The right block is key for ensuring that structural checks are passed with flying colours. 

What Is a Concrete Block?

A dense aggregate concrete block is manufactured to BS EN 771-3 using sand, gravel and cement. The result is a heavy, strong, reliable unit built for structural work. Dense concrete blocks come in three standard sizes: 100mm, 140mm and 215mm. Each targets a different application, from partition walls at 100mm through to full cavity or solid wall construction at 215mm. Compressive strength is the key selling point. Dense blocks typically achieve 7.3N/mm² or higher, making them suitable for foundations, retaining walls and load-bearing applications where failure simply isn't an option.

What Is a Breeze Block?

Breeze blocks were originally made using the ash residue left over from burning coke. That manufacturing process is largely obsolete now. When people say "breeze block" today, they usually mean one of two things: a dense concrete block incorrectly labelled, or an aerated block. Aerated blocks are made by introducing air bubbles into the mix during production. They're lighter, easier to cut, and provide considerably better thermal performance than dense concrete. Modern building regulations have pushed aerated blocks into widespread use on new builds, largely replacing old-style breeze in most above-ground scenarios. If someone on site asks for a breeze block, it's worth confirming what they actually need before placing the order.

Concrete vs Breeze Blocks: Head-to-Head

How Many Blocks in a Pack?

Pack quantities vary by block size, so here's what to expect at the point of order:

To calculate your own requirement: measure the wall area in m², divide by 0.08m² (the face area of a standard 440x215mm block), then add 10% for waste and cuts. That gives you your block count. Divide by the pack quantity to get the number of packs to order. It's a simple calculation but worth doing properly before you buy, since short deliveries on a block order can cost more in redelivery charges than the extra pack would have.

Which Block Should You Buy?

• Strip or trench fill foundations: Dense concrete 215mm 

• Retaining wall or below DPC: Dense concrete 

• 100 mm or 140 mm internal partition wall: Aerated block 

• 100mm Cavity wall inner leaf: Aerated block 

• 100 mm or 140 mm garden wall or planters: Dense concrete 

• 100mm New build structural inner leaf: Aerated block

FAQs

Can you use breeze blocks for foundations? 

Not aerated blocks. Below DPC and in ground contact, you need dense aggregate concrete blocks. Aerated blocks absorb moisture and will deteriorate quickly if used below ground.

Are concrete blocks load-bearing? 

Yes. Dense concrete blocks are specifically used in load-bearing situations. Always check the compressive strength specification against your structural requirements before ordering, and confirm with your structural engineer if you're unsure.

How heavy is a concrete block? 

A standard 100mm dense concrete block weighs around 8.5 to 10kg. A 215mm block can reach 20kg or more. Worth factoring in when pricing labour, planning how materials are distributed on site, or assessing what vehicle access you'll need for delivery.

Order Blocks at Emerys

Dense concrete blocks in 100mm, 140mm and 215mm, plus aerated blocks, are available from both our Telford and Stoke branches. Shop online or give us a shout to find out more about blocks.