On one hand I can see where engineered bricks could make up for the height difference, on the other hand if you're expecting the slab to become a monolith upon completion, the different size supporting members must make sor some messy calculations for the designer. Then again maybe not, because each section is supported seperately.  I thought about the additional cost of the additional course of bricks but there is no additional course because the 225mm beam section would actually carry one less course, support would only be needed for the 155mm beams.

 

I can see hoe the split installation would work ok when building with brick but I can't see it working as smoothly when working with block foundations.  Am I missing something here?

Perhaps an extra layer of 70mm insulation on top of the 155mm beam area?

 

 

We usually aim to have the top of the beams level in this situation unless one part of it is an attached garage where the floor level needs to be reduced. 
Even if the rest of the foundation is in blocks there are always concrete coursing bricks that you can use to reduce the level of the walls below beam and block. 
 

However this needs thinking about at the design stage. If you have two different depths of beams bearing on a 100mm wall you will need to increase the width of the wall to 215 mm to allow you to split the beams. 

Edited January 23, 20251 yr by Canski

15 hours ago, Canski said:

We usually aim to have the top of the beams level in this situation unless one part of it is an attached garage where the floor level needs to be reduced. 
Even if the rest of the foundation is in blocks there are always concrete coursing bricks that you can use to reduce the level of the walls below beam and block. 
 

However this needs thinking about at the design stage. If you have two different depths of beams bearing on a 100mm wall you will need to increase the width of the wall to 215 mm to allow you to split the beams. 

As you say, this has to be well thought out during design, but can be done even with blocks. If blocks of the right height can't be bought, they can be cut.  If there is a section of a foundation that needs 215mm beams,then the rest has to be worked out.

 

I'm guessing that the designer would spec out the rest of the job with 215mm beams unless there was a huge cost savings, inclusive of the needed modifications.

Edited January 24, 20251 yr by Boyblue