Concrete & Aircrete Blocks

What we supply

• Dense concrete blocksHeavy, strong blocks for loadbearing walls, below ground and good sound separation.
• Lightweight aggregate blocksLighter to handle with better thermal performance than dense blocks.
• Aircrete (aerated) blocksVery light, easy to cut and good insulators; check the strength grade for loadbearing work.
• Trench and foundation blocksWide blocks laid in foundation trenches instead of lots of concrete.
• Hollow and cellular blocksLighter dense blocks with voids, used for some garden and retaining walls.
• Block paving and edgingsOn request alongside your sub-base and sand.

Sizes and specifications

Face size	440 × 215 mm (thicknesses 75 to 215 mm)
Coverage	About 10 blocks per m²
Strength grades	Commonly 3.6 N/mm² and 7.3 N/mm²
Standard	BS EN 771-3 (aggregate), BS EN 771-4 (aircrete)

Sizes and standards are typical for the UK market; exact figures depend on the manufacturer and are confirmed on your quote.

Common uses

• Inner leaf of cavity walls
• Internal partitions
• Foundations and below-DPC work
• Garages and outbuildings

Choosing concrete blocks

What strength do I need?

Most houses use 3.6 N/mm² or 7.3 N/mm² blocks. Your structural design, your building control officer or the block manufacturer's guidance sets the grade; tell us what is specified and we will match it.

Dense or aircrete?

Dense blocks are strong and good for sound separation but heavy; a 100 mm dense block can weigh around 20 kg. Aircrete blocks are much lighter and insulate better, which helps with energy targets, but need the right fixings.

Thickness

100 mm is the common inner-leaf thickness. Wider blocks (140, 190, 215 mm) are used for separating walls, single-skin garage walls and foundations.

Handling heavy blocks

Health and safety guidance discourages laying very heavy blocks by hand for long periods. Lighter blocks or planning the lift can make a big difference on site.

Building regulations differ across the UK. In England, building work is checked against the Approved Documents, for example Part A for structure and Part L for energy efficiency, through your council's building control team or a registered building control approver. Wales has its own Approved Documents, including its own Part L for energy efficiency, and building control is handled by the local authority or a registered approver. In Scotland most building work needs a building warrant from the local authority, assessed against the Building Standards Technical Handbooks. In Northern Ireland building work follows the Building Regulations (Northern Ireland), with guidance in the Technical Booklets, and applications go to the council's building control team.

How it arrives on site

Blocks are banded on pallets and usually crane-offloaded where the vehicle and access allow; tell us the weight limit of any drive or the ground where pallets will sit. We agree the drop point and offload method when we price your order. Read more about how delivery works.

How much do you need?

A single-skin block wall 6 m long and 2.1 m high is 12.6 m². At 10 blocks per square metre plus 5% you need 133 blocks, with about 0.18 tonnes of building sand and 2 bags of cement for the mortar at 1:4. Try the block calculator

Concrete & Aircrete Blocks: questions

How many blocks per square metre?

Standard 440 × 215 mm blocks with 10 mm joints lay at about 10 blocks per square metre of wall. Add around 5 percent for cuts.

What is the difference between 3.6 and 7.3 N/mm² blocks?

The number is the compressive strength. 7.3 N/mm² blocks carry more load and are often specified below ground or for heavily loaded walls; 3.6 N/mm² is common for upper storeys and partitions. Follow your drawings.

Are aircrete blocks strong enough for an extension?

Many aircrete blocks are designed for loadbearing walls, but grades differ. Check the strength your design calls for and the manufacturer's guidance on use below DPC.

How heavy is a concrete block?

It depends on the type and thickness. A 100 mm dense block is roughly 18 to 20 kg, a lightweight block noticeably less, and an aircrete block much less again.

Can I use blocks in the foundations?

Yes, using blocks made for below ground, often trench blocks or dense blocks of the specified strength. Building control will check foundation design.

How many blocks on a pallet?

It varies with the block size and maker. We confirm the pallet quantity with your price.

How much mortar for blockwork?

Roughly 0.008 to 0.01 cubic metres of mortar per square metre of 100 mm blockwork, allowing for waste. Use our block calculator for sand and cement quantities.