Ultralight blocks interfaced with medium dense blocks render requirements

[Rudski]

Morning everyone

 

My structural engineer has mis sized my structural steel for holding up external blockwork above the patio doors, i've had it fabricated and galvanized! Without getting into the why's on here he has proposed using a ultralight block above this area as his new calcs make this acceptable, there is a 30 pence difference between a medium and lightweight block so was just going to use the ultralight on the steelwork up to eaves to save on expense, the data sheet for this block gives excellent adhesive qualities for render applications, I'm awaiting a response from K rend on the requirements at the interface between the different blocks, different primers/ more mesh to prevent cracking etc.

 

In the mean time is there anybody on here that has done this already or have any specific knowledge/advice of this?  Just to note this isn't a thermalite block.  Attached datasheet for block below

 

TIA   

_Ultralite Datasheet - January 2025.pdf

[Mr Punter]

I would be concerned if the steel won't hold up a standard med dense block within the allowed limits.  In addition to the mesh for the render, you could look at bed reinforcement for the blocks.  Only use the 7.3N ones.