Putting clay bricks over blocks

[James45632]

Can clay bricks be mixed with (either aerated or dense) concrete blocks in a single wall?

I thought they can't be mixed because of their different u-values and how they shrink/expand at different rates which would produce cracking. Yet I see a lot of mixed brick and block wall construction like the in the photos attached.

The reason I ask is that I've got to rebuild a brick wall to imbed new joists back into it and I'm hoping I can build it up using something like aerated blocks (about 5.2n thermolite blocks).

 

[^woody^]

Yes you can do that. Expansion rates are not an issue and different uvalues are theoretically significant on paper not in real life.

 

[geraldthehamster]

I've just watched a new estate of near-identical boxes going up (detached houses rammed in a foot apart). Every tiny area that would be covered by render or a porch was done in blocks, in outer skins that were otherwise in brick. Penny pinching

 

[stuart45]

It's standard nowadays for rendered work to be built in blockwork.

 

[James45632]

Yes you can do that. Expansion rates are not an issue and different uvalues are theoretically significant on paper not in real life.

I've just watched a new estate of near-identical boxes going up (detached houses rammed in a foot apart). Every tiny area that would be covered by render or a porch was done in blocks, in outer skins that were otherwise in brick. Penny pinching

Yeah, I understand why they'd want to penny pinch given that for the same area, bricks are 6 times more costly than blocks. That adds up fast when it comes to estates. But even the NHBC says not to mix them but I guess in practise, like Woody said, it doesn't make much of a difference:

Clay bricks and concrete blocks should not be mixed. Where a different size of masonry unit is needed to ensure correct coursing, small units of the same material should be used to reduce cracking and problems due to different thermal insulation properties.

 

[stuart45]

It's more for internal walls where that applies. Years ago bricks were often stuck into the reveals with a thermalite block wall, and also at the corners to make the bond.