Concrete Blocks vs Thermalite Blocks
Concrete blocks and Thermalite blocks are both used for masonry construction, but they have different properties.
The right block depends on the wall construction, required strength, thermal requirements and project specification.
Advice by Andrew Tsaroulla, Director of TSAR Building Supplies
Last updated: 10th October 2026
What Are Concrete Blocks?
Dense concrete blocks are strong masonry units used in a range of building applications.
TSAR supplies heavy solid concrete blocks as well as hollow concrete block products in different thicknesses and strength ratings.
What Are Thermalite Blocks?
Thermalite blocks are lightweight aircrete blocks.
They are lighter than dense concrete products and have different thermal and handling characteristics.
TSAR supplies Thermalite Shield, Hi-Strength and Party Wall products.
What Is the Main Difference?
How Do the Blocks Compare?
This comparison focuses on dense concrete blocks and Thermalite aircrete blocks. Check the individual product specification when ordering.
| What to compare | Dense concrete blocks | Thermalite aircrete blocks |
|---|---|---|
| Weight and handling | Generally heavier for a comparable block size | Generally lighter for a comparable block size |
| Strength | Check the stated compressive strength of the selected block | Check the stated compressive strength of the selected block |
| Thermal performance | Use the declared thermal properties in the wall design | Use the declared thermal properties in the wall design |
| Fixings and finishes | Follow guidance for the selected concrete block | Use fixings and finishes suitable for aircrete |
| Product choice | Match the block to the wall specification | Match the block to the wall specification |
A lighter block is not automatically suitable for every wall, and a heavier block is not automatically the right choice for every structural application.
Compare the exact products against the required strength, thickness and complete wall construction before ordering.
What Do Block Strength Ratings Mean?
Block compressive strength is expressed in N/mm². Product descriptions sometimes shorten this to figures such as 3.6N or 7.3N.
Check the strength required by your project specification alongside the block type and thickness. The strength figure alone does not determine whether a block is suitable for a particular wall.
You may see ratings such as 3.6N or 7.3N on block products.
These refer to the compressive strength of the block.
The required strength should follow the masonry or structural specification for the project.
Which Block Should I Use?
Check the drawings or specification for:
Block type
Thickness
Required strength
Wall construction
Thermal requirements
Related Building Advice
What Do Block Strength Ratings Mean? → future page
Concrete Lintels vs Steel Lintels → future page
View Blocks
General guidance only: Block type and strength should follow the relevant project or structural specification.