Rendered Blockwork Cavity wall with 7KN blocks?

[designgrey]

Hi. A friend recommended the following make up to acheive a 0.28 u value.
Rendered Blockwork, 100mm Dritherm 32, 100mm (0.16) for the inner leaf. He suggested Toplite but I can only see them in 3.6kn. Because of a lot of steel, I would like to use 7kn but I cant find a block with a matching (to the toplite) U value.
Basically does anyone recommend a way?
Thanks

 

[Bonni]

Just buy a celcon block with the grade you want.

https://www.hhcelcon.co.uk/solutions/by-product/celcon-blocks