Aerated Blocks
Aerated Blocks & Thermalite Blocks for UK Building Projects
Shop aerated blocks at JJ Building Materials for lightweight masonry, internal and external wall construction and projects where easier handling and improved thermal performance are important. Our live range includes Forterra Thermalite blocks in 100mm, 140mm and 215mm formats, including Thermalite Shield and Thermalite Turbo products with different declared compressive strengths.
Aerated concrete blocks are manufactured with a cellular structure that reduces weight compared with many dense concrete products. This can make them easier to lift, cut and shape on site while also giving useful thermal characteristics. The right block still depends on wall type, loading, exposure, acoustic requirements, thermal design and the project specification, so always choose from the declared product performance rather than size alone.
100mm Thermalite Blocks
Our 100mm Thermalite blocks include the Forterra Thermalite Aircrete Shield 3.6N block. A 100mm aerated block is a common format for a wide variety of masonry details, but suitability depends on the wall design and specification. Check the declared strength, dimensions, pack quantity and intended application before ordering.
140mm Thermalite Blocks
For projects requiring a wider block, compare the 140mm Thermalite Aircrete Shield. Increasing block width changes the wall build-up and may affect thermal, structural and dimensional performance, so the 140mm option should be selected to suit the drawing or specification rather than treated as a direct substitute for 100mm blocks.
215mm Aerated Blocks
The collection also includes the 215mm Thermalite Aircrete Turbo. The product is 215 x 215 x 440mm and provides a larger-format aerated block option for relevant wall constructions. Because this product has a different strength designation from the Shield products, check the project's structural and thermal requirements carefully before choosing.
Thermalite Shield Blocks
Thermalite Shield is represented in the live JJ Building Materials range in 100mm and 140mm 3.6N blocks. These lightweight aerated concrete blocks are designed for suitable masonry applications and can be easier to handle and cut than dense concrete alternatives. Product performance should always be checked against the Forterra technical information and the building design.
Thermalite Turbo Blocks
Thermalite Turbo blocks offer another aircrete option within the range. Our current 215mm Turbo product has a declared 2.9N compressive strength. Do not assume Turbo and Shield products are interchangeable: compare block dimensions, strength, thermal properties and the requirements of the wall before ordering.
Aerated Concrete Blocks vs Dense Concrete Blocks
Aerated concrete blocks and dense concrete blocks are different masonry products. Aircrete is lighter and generally easier to cut and chase, while dense concrete blocks are typically heavier and may be specified where different strength, density or acoustic characteristics are required. Neither type is automatically 'better' for every project.
If you are comparing block types, browse our concrete blocks collection alongside these aerated blocks. For the wider masonry range, see bricks and blocks.
2.9N vs 3.6N Aerated Blocks
The strength figure shown in an aerated block name relates to its declared compressive strength class. A 3.6N product has a different declared strength from a 2.9N product, but the highest number is not automatically the correct choice. The wall designer or project specification should determine the required block performance.
Always check whether a particular wall is load-bearing or non-load-bearing, the number of storeys, concentrated loads, lateral support, exposure, movement joints and any other design factors. Where structural design is required, follow the engineer's or designer's specification.
Choosing the Right Aerated Block Size
Start with the specified wall thickness. A 100mm, 140mm or 215mm block changes the overall wall build-up, so use the drawings and construction details as the primary reference. Then compare strength, thermal requirements, product dimensions and pack quantities. If you are estimating quantities, calculate the wall area and use the face dimensions of the exact product, allowing for openings and a sensible waste factor.
Cutting & Fixing into Thermalite Blocks
One reason builders choose lightweight aerated blocks is that they can be easier to cut and shape than dense masonry. Use appropriate tools, control dust and follow site safety requirements. Fixings should be chosen specifically for the load and the aerated substrate; ordinary plugs are not suitable for every load.
For heavier fixtures, check the fixing manufacturer's stated suitability for aerated concrete and consider the required embedment, edge distances and load category. The block itself is only one part of the fixing system.
Laying Aerated Blocks
Aerated blocks should be laid in accordance with the project specification and relevant workmanship guidance. Keep courses level and plumb, maintain the required bond and joint thickness, and protect fresh masonry from adverse weather. Mortar choice should be compatible with the block and construction detail.
Because aircrete can absorb moisture differently from dense masonry, good site storage matters. Keep packs stable, protect them from prolonged saturation and handle blocks carefully to reduce chipped corners and unnecessary waste.
Why Buy Aerated Blocks from JJ Building Materials?
JJ Building Materials stocks genuine Forterra Thermalite products in useful UK building sizes, allowing customers to compare 100mm, 140mm and 215mm options in one collection. Product pages show the exact dimensions, strength designation and pack quantity so you can match the order to the job rather than relying on generic block descriptions.
You can also source related building supplies, engineering bricks, facing bricks and brick accessories from the same site.
Aerated Blocks FAQs
What are aerated blocks?
Aerated blocks, often called aircrete blocks, are lightweight concrete masonry units with a cellular internal structure. They are used in a range of wall constructions where their declared strength, dimensions and thermal characteristics meet the project requirements.
Are Thermalite blocks aerated concrete blocks?
Yes. Thermalite is Forterra's aircrete block range. Different Thermalite products have different sizes, strengths and performance characteristics, so always check the exact product specification.
What is the difference between 100mm and 140mm Thermalite blocks?
The main obvious difference is block width, which changes the wall build-up. The correct width depends on the construction detail and specification. Do not substitute one size for another without checking the design.
What does 3.6N mean on a Thermalite block?
It refers to the block's declared compressive strength classification. It should be matched to the structural requirements of the wall rather than chosen purely because it has a higher number than another product.
Can you cut Thermalite blocks?
Yes, aerated blocks are generally straightforward to cut with suitable masonry tools. Use appropriate PPE, dust control and accurate setting-out to reduce waste.
Can you screw into aerated concrete blocks?
Yes, but the fixing must be suitable for aerated concrete and for the intended load. Use the fixing manufacturer's guidance, particularly for heavier items.
Are aerated blocks better than concrete blocks?
They serve different needs. Aerated blocks are lighter and can offer useful thermal performance and easier workability, while dense or hollow concrete blocks may be selected for different structural, density or acoustic requirements.
How many aerated blocks do I need?
Calculate the net wall area after subtracting openings, divide by the face area of the exact block, then add a sensible allowance for cuts and waste. Pack quantities vary between products.
Aerated Blocks Buying & How-To Guides
Use these detailed guides to compare Thermalite products, understand block sizes and strengths, and plan cutting, fixing and installation work.
- Aerated Blocks Buying Guide: Thermalite Sizes, Strength & Uses
- Thermalite Shield vs Turbo: Which Aerated Block Should You Use?
- 100mm vs 140mm vs 215mm Aerated Blocks: Size Guide
- 2.9N vs 3.6N Aerated Blocks: Compressive Strength Explained
- How to Lay, Cut & Fix into Aerated Concrete and Thermalite Blocks
