Thermalite Shield vs Turbo: Which Aerated Block Should You Use?
Thermalite Shield vs Turbo: Which Aerated Block Should You Use?
Thermalite Shield and Thermalite Turbo are both Forterra aircrete blocks, but they are not identical products. Shield 3.6 is denser and has a higher declared compressive strength, while Turbo 2.9 is lower density and has a lower design thermal conductivity. Choosing between them should therefore be based on the wall design rather than assuming one range is simply better.
JJ Building Materials stocks 100mm Thermalite Shield 3.6N, 140mm Thermalite Shield 3.6N and 215mm Thermalite Turbo 2.9N. This guide compares their technical characteristics and practical uses.
Quick Thermalite Shield vs Turbo Comparison
| Property | Thermalite Shield 3.6 | Thermalite Turbo 2.9 |
|---|---|---|
| Declared compressive strength | 3.6 N/mm² | 2.9 N/mm² |
| Design thermal conductivity | 0.15 W/mK | 0.11 W/mK |
| Dry density | 600 kg/m³ | 470 kg/m³ |
| Face dimensions | 440 x 215mm | 440 x 215mm |
| JJBM stocked widths | 100mm, 140mm | 215mm |
These are Forterra's published headline values for the ranges. Always use current manufacturer data and the project specification when making a final selection.
What Is Thermalite Shield?
Thermalite Shield is a versatile 3.6N aircrete range. Forterra lists uses including external walls, foundations, partitions and separating walls where the product is suitable for the design. Its cellular structure provides a combination of light weight, thermal insulation and masonry strength.
At JJ Building Materials, Shield is currently available in 100mm and 140mm widths. Both have the same 440 x 215mm face dimensions but different block thicknesses and pack quantities.
What Is Thermalite Turbo?
Thermalite Turbo is a lower-density 2.9N aircrete block with improved thermal conductivity compared with Shield. Forterra publishes a design λ value of 0.11 W/mK, versus 0.15 W/mK for Shield. The lower density also reduces unit weight for the same block dimensions.
JJ Building Materials currently stocks a 215mm Turbo block. Because this is both wider and a different range from the stocked Shield products, a direct price-per-block comparison does not tell you which is right for a wall.
Strength: 3.6N vs 2.9N
Shield's 3.6 N/mm² declared compressive strength is higher than Turbo's 2.9 N/mm². If the design requires at least 3.6N masonry units, a 2.9N Turbo product should not be substituted without approval. Wall strength is influenced by block, mortar, geometry, restraint and loading, so follow structural calculations where applicable.
Higher strength does not automatically mean a better wall. A design may legitimately select 2.9N Turbo because its strength is adequate and its thermal performance supports the overall wall target.
Thermal Performance: 0.15 vs 0.11 W/mK
Thermal conductivity is one of Turbo's key advantages. A lower lambda value means less heat is conducted through a given thickness of material. Turbo's 0.11 W/mK design value is lower than Shield's 0.15 W/mK, which can help a wall build-up meet thermal targets.
Do not confuse block lambda with whole-wall U-value. Insulation, cavities, mortar joints, finishes, thermal bridges and junctions all contribute. The designer should calculate the complete construction.
Density and Handling
Forterra lists a dry density of 600 kg/m³ for Shield and 470 kg/m³ for Turbo. Lower density generally means a lighter block at the same size, although the actual 215mm Turbo stocked by JJ Building Materials is much wider than the 100mm and 140mm Shield products.
Consider individual unit dimensions and weight when planning manual handling. A very wide lightweight block can still be physically large and awkward, so safe handling remains important.
100mm Thermalite Shield
The 100mm Shield is a common aircrete format for wall leaves and partitions where 100mm thickness is specified. Its 3.6N strength and 440 x 215mm face make it a versatile choice, but final suitability depends on wall height, loading and performance requirements.
JJ Building Materials sells the 100mm Shield in packs of 60. At around 10 blocks per m² as an initial estimate, one pack may cover roughly 6m² of wall face before allowing for waste, although exact coverage depends on joints and layout.
140mm Thermalite Shield
Moving to a 140mm Thermalite block changes wall thickness and can support a different structural or thermal build-up. The stocked Shield 140mm still has 3.6N declared strength but contains more material per unit and is sold in smaller pack quantities.
Do not replace 100mm with 140mm without checking cavity width, window reveals, door linings and total wall dimensions.
215mm Thermalite Turbo
The stocked 215mm Turbo is a substantial aircrete unit measuring 215 x 215 x 440mm. At this width, it can form a much thicker masonry element than the 100mm or 140mm Shield products. Its 2.9N strength and 0.11 W/mK thermal conductivity give it a different performance balance.
Read our aerated block size guide before selecting a width.
Which Is Better for Thermal Insulation?
On material conductivity alone, Turbo's lower λ value indicates better thermal resistance for a given thickness. But because stocked widths differ, whole-wall comparison must use the actual thickness and full construction. A 215mm Turbo and a 100mm Shield are not like-for-like products.
Which Is Better for Strength?
On declared compressive strength alone, Shield 3.6 is higher than Turbo 2.9. Whether that difference matters depends on the design loads. For load-bearing masonry, use the specified strength category and seek design approval for substitutions.
Which Is Easier to Cut?
Both are aircrete and are generally easier to saw and shape than dense concrete blocks. Turbo's lower density can make cutting feel easier, but tool choice, block width and cut geometry matter. Use suitable masonry tools and dust control.
Which Is Better for Fixings?
Both require fixings suitable for aerated concrete. Shield's higher density may influence anchor performance, but do not assume a fixing rated for one aircrete grade will automatically carry the same load in another. Use fixing-manufacturer data for the exact substrate and load.
For practical fixing advice, see how to lay, cut and fix Thermalite blocks.
Can You Mix Shield and Turbo in One Project?
Different Thermalite ranges can be used on the same project where the drawings and details specify them for different walls or locations. They should not be mixed randomly within a single wall as a convenience substitution. Differences in strength, density and thermal properties can matter to the design.
Mortar for Shield and Turbo
Use mortar compatible with the chosen aircrete block and wall specification. The correct mortar designation should consider block strength, exposure and structural design. Maintain consistent bed and perpend joints and follow workmanship guidance.
Quantity and Pack Planning
All three stocked JJ Building Materials products have a 440 x 215mm face, so the number of blocks per square metre is broadly similar for the wall face. Around 10 units per m² is a useful early estimate with standard joints. What changes is pack quantity: 60 for 100mm Shield, 40 for 140mm Shield and 25 for 215mm Turbo in the current live range.
When Shield Is Likely to Be the Better Choice
- Where the design specifies 3.6N aircrete.
- Where 100mm or 140mm wall thickness is required.
- Where Shield's density and performance match the wall specification.
- Where its pack format suits the project quantities.
When Turbo Is Likely to Be the Better Choice
- Where 2.9N is structurally suitable.
- Where improved aircrete thermal conductivity is beneficial.
- Where the specified wall uses the stocked 215mm width.
- Where the complete construction has been designed around Turbo performance.
Shield vs Turbo FAQs
Is Thermalite Shield stronger than Turbo?
Shield 3.6 has a higher declared compressive strength than Turbo 2.9.
Is Turbo better insulation than Shield?
Turbo has a lower published design thermal conductivity of 0.11 W/mK versus 0.15 W/mK for Shield, but whole-wall U-value depends on the full build-up.
Can I replace Shield with Turbo?
Only if the design confirms the change is suitable. Strength, density, thermal performance and available widths differ.
Can I replace Turbo with Shield?
Again, not automatically. A higher-strength block can still change the thermal and dimensional design.
Are both easy to cut?
Both are lightweight aircrete products and can be cut with suitable tools. Use dust control and accurate setting-out.
Do Shield and Turbo use the same fixings?
Both need aerated-concrete-compatible fixings, but allowable loads should be checked for the exact block and anchor system.
How many Thermalite blocks are needed per m²?
Approximately 10 units per m² is a common preliminary figure for 440 x 215mm face blocks with typical joints.
Where can I buy Thermalite Shield and Turbo?
Browse JJ Building Materials' Thermalite and aerated blocks collection for live products.
Final Recommendation
Use Shield when the wall calls for its 3.6N strength and available widths; use Turbo when its 2.9N strength, lower density and thermal characteristics suit the design. The name on the block is less important than matching the product data to the complete wall specification.