Joining blocks of different types

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Hello

 

We have an internal wall that will support the roof, these are 7.3 150 * 215 * 440 (so wide) hollow concrete blocks.

 

What's the best way to join a 90 degree intersection with standard size blocks which are thermalite.

 

 

These 

 

To  these

 

 

The concrete ones will be filled with mortar and will be the top of the 'T' for internal walls and the vertical of the T joining the cavity wall.

rough picture below.

The cavity wall also goes the bottom side of the celcon.

 

 

 

 

Do we use one of these

 

 

 

Or, tooth the blocks into each other.