Vertical cracks straight through breeze block

[AtoZ]

thermolite told me that they still offer a structural guarantee if their cracks are vertical.
i used that glue system on my own house with the big format blocks.
i have 1 metre deep foundations in virgin soil.
i had a 9 metre wall with three seperate expansion joints when i didnt need them. the blocks were 7nm blocks
i had the thrmolite rep and one of their technical staff watching me as i laid the blocks as i was their first private customer.

it is my house, i did all the work. every screw is stainless steel, all the wall ties are stainless and way over specified. everything is over specified because im a fussy git.

all of the block walls split vertically !
as you can imagine i was not impressed.
thermolite said it was normal.

i cut off the render and put on a plastic/fibre glass mesh and re-rendered.
that was several years ago and there has not been a problem since.

my concern was that water would get behind the old render and blow it.

i was ****ed like you are but i dont think it is a big worry at all.

 

[Shytalkz]

Vertical cracks of constant width = horizontal strain in the masonry = thermal expansion/contraction (or overstressing), not foundation movement.

Lightweight AAC blocks are well known for this. If the blocks were either wet when laid, or got wet after laying, then as they dry they will shrink. Movement joints are required at 6m spacings in blockwork, including around corners. Put them in at requisite centres and they will still tend to crack, just some place else, often where there is a change in the stressses in the block, eh below structural openings.

The rubble is an interesting comment, but is a red herring for the type of cracking described by the OP.

 

[AtoZ]

Vertical cracks of constant width = horizontal strain in the masonry = thermal expansion/contraction (or overstressing), not foundation movement.

Lightweight AAC blocks are well known for this. If the blocks were either wet when laid, or got wet after laying, then as they dry they will shrink. Movement joints are required at 6m spacings in blockwork, including around corners. Put them in at requisite centres and they will still tend to crack, just some place else, often where there is a change in the stressses in the block, eh below structural openings.

The rubble is an interesting comment, but is a red herring for the type of cracking described by the OP.

im very happy to have read this post reassuring