I got an everlasting problem with a aerated autoclaved concrete (also known as "Gasbeton") wall: there's a crack that seems to split the upper half from the bottom half of the wall.

I tried several time to fix it, either with the proper aerated autoclaved concrete putty and with stucco but, after some days, the crack comes back again.

Any idea on how to fix it for good?

EDIT: The wall is made of AAC blocks (as bricks), I have access to both sides and is an interior wall: basically it divides one former big room in two smaller rooms (kitchen and bedroom).

  • Is this wall a huge slab of AAC or is it AAC blocks? Do you have access to the wall on both sides? Interior or exterior?
    – JD Long
    Jul 29, 2010 at 14:52
  • Please, see the edit. I tried to add some infos about.
    – dag729
    Jul 29, 2010 at 23:09
  • Is the crack getting bigger? After you fix it, what happens when you say it comes back? Jul 30, 2010 at 1:19
  • It just seems that the putty...disappears! Where the crack was, the crack will be... Same measures as before.
    – dag729
    Jul 30, 2010 at 11:05

1 Answer 1


Instead of trying to fix the crack, first try figuring out what is causing the crack. You can fix a crack many times, but if you are fighting against something like water pressure (or one of the many other causes of cracks in concrete), you will never win. Once you find what is causing the crack, then look to mitigate the problem somehow (proper drainage in the case of water buildup), and then fixing it one final time will take care of the problem.

  • Where would one begin?
    – spoulson
    Jul 27, 2010 at 20:35
  • I think that the issue is with the wall settlement, but since the crack come back again and again, I'm not so sure. If that was the case, how do I proceed to fix it?
    – dag729
    Jul 28, 2010 at 20:38
  • Considering that you have tried to fix the wall several times, I just assumed it has been there for quite some time so settling would have stopped. If it continues to settle then there is a problem with its foundation, which needs to be corrected... although that is probably not so easy. Where is the wall located and what is its purpose? Jul 29, 2010 at 13:16
  • Added some (useful?) infos to the question.
    – dag729
    Jul 29, 2010 at 23:09

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