Crack in garden wall after about 8 months

[DIYalot]

Hi. At the back of my garden, my neighbour had put up a wall made of largish blocks. They look grey and are like the size of the old breezeblocks. It's actually a retaining wall, (holding back about 90 Cm high soil) of two parts. The bottom part the blocks are arranged such that the width of the wall, is the same as the width of the blocks, This is the retaining part. On top of that sits a wall structure made of the same blocks, but it's thickness is as the depth of a block, thinner than the width..

After about 8 months there has developed a crack in the wall, roughly midway. Here are some fact that may or not be relevant:

* Length of wall about 40 foot. All as one continuous wall.
* No weepholes.
* I measured the depth of the foundation. It's 38Cm or so. Similar width I think.
* I don't see any crack in the foundation near where the crack is.

The foundations look Okay, but because the shuttering was less than perfectly rectanglar, the wall actually skews across the foundation from one end to the other in order to sit on the foundation. Also, on my side (the lower ground - neighbours land is 90Cm higher) the foundation top surface is not below ground, it's about 80mm above my garden surface.

I don't belive the wall presnts a danger, I'm just curious is to why that crack has appeared after such a short time. Thanks if you can offer insight on this.

 

[Koolpc]

Probably just a bad mix i would say...

 

[tony1851]

Concrete blockwork is known for shrinkage cracking - nothing unusual there.
They usually put movement joints in about every 6m or so - that's why its cracked near the middle.

 

[DIYalot]

OK, so it's not that the foundation is sinking down at one end (say) it's just material shrinkage. The wall is actually 47 feet long (abt. 14 meters) with no movement joint. Would this wall benefit from being cut in the middle to create an expansion joint? Or, would you not bother?

 

[freddiemercurystwin]

Probably but the movement joint would ideally need to go from the top down to the foundation. Are there no piers in that single skin on top? Presumably this wall must be about 1.8m high on your side?

 

[DIYalot]

Probably but the movement joint would ideally need to go from the top down to the foundation. Are there no piers in that single skin on top? Presumably this wall must be about 1.8m high on your side?

The wall is 226Cm high from the foundation, which on my side protrudes above ground about 10Cm. The bottom 90cm is retaining and the width is the width of a block. On top of that, the same blocks, but the width is the depth of a block (i.e. smaller). There are no buttresses or whaever on my side. Of course. wall cannot realistically fall into next door garden, only mine. So, if a machine was used to chase out a gap, it would need to be done from my side. And I'd need permission from my neighbour to do that.