Single Storey Extension Blocks

[boycey9]

Hi, I am having a single storey extension built which I am managing myself and getting various trades to complete for me.
The specifications for the walls are a single skin with 215x215x440 Thermalite Turbo blocks.
I am not finding these easy to source at a good price, Can I use the Shields instead?, whats the main difference between them. Is there any alternative I can get from selco or local builders merchants.

 

[^woody^]

Shields are lower in thermal efficiency. You need an equivalent block of 0.11W/mK

Or use two 100mm blocks which will be less than the price of one 215mm block

 

[boycey9]

Thank you