Bond Beam v Control Joint

[MikeStout]

There is something I do not understand and would be grateful for clarification.

The idea of a control joint is to allow a wall to move and therefore prevent it from cracking. At the same time we put rigid elements such or a bond beam that prevent movement.

Do we really need control joints in an inner leaf of a cavity wall, and if so how do we deal with the bond beam?

 

[tony1851]

Proprietory bond beam systems have sleeved anchors at the ends which allow for a small degree of movement, usually through initial shrinkage (thermal movement of an inner skin is less of an issue than on the outer skin, for obvious reasons).
As a matter of interest, why the question? Bond beams are not often found in domestic work.

 

[MikeStout]

Thanks for the advice. As far as a bond beam is concerned I find it a bit confusing. From the European perspective a bond beam is a compulsory element on buildings made of aerated concrete blocks. However, I do not see it even mentioned in my British books. Why is that?

 

[tony1851]

Don't know? AAC block is of course notorious for shrinkage, but never seen bond-beams used with it in domestic buildings.

 

[MikeStout]

So, if I use a conventional CMU, not AAC, I don’t need a bond beam? Honestly, a comparative approach can be eye opening.

 

[^woody^]

Are these "bond beams" a foreign thing, or do I need to update my edition of Chudley?

 

[MikeStout]

Well, I have Chudley and a few other books and none of them mentions bond beams. I thought I was missing something.