blocks for a garden retaining wall?

[mikebucks]

HI, I am building a retaining wall about 4' high that will hold back the increase in garden hieght between me nd my neighbour and am thinking about using medium density blocks laid flat to create a 9" wide wall rendered and with coping on top. Is there any problem using these as opposed to dense concrete? I have built a 11m wall with the dense ones and was hoping to avoid using them again if necessary! Or will I have to just get on with the dense concrete blocks? Thanks . Mike

 

[Deluks]

The heavier blocks have a higher compressive strength, which doesn't really apply to a retaining wall of this height, so yes you can use them.
Don't forget the drainage!

 

[Static]

The heavier blocks have a higher compressive strength, which doesn't really apply to a retaining wall of this height, so yes you can use them.
Don't forget the drainage!

But of course the heavier the block the heavier the wall and thus the greater the friction resistance to sliding and the resistance to overturning..

 

[mikebucks]

Thanks, does this mean that the compressive strength is unimportant and that 3.5n is good enough. If so , and considering the comments made are they also heavy enough to do the job.?

 

[noseall]

Use 7n dense fellas.

 

[studips]

adequate foundation and hollows for me (infilled with 1:5) and rebar set in the foundation and up through the blocks for me, depending on how much pressure it will need to resist and how high it will be you can scale that back.

last wall i did like that was spec'd by a structural engineer (the customer to be exact) & was on a metre depth of concrete..........

it still gives me the shakes when i think about it..........

 

[Blagard]

HI, I am building a retaining wall about 4' high that will hold back the increase in garden height between me and my neighbour

I was not sure what you were actually doing here. Is this wall on the boundary between you and your neighbour and if so, on your side, are you cutting away ground or building up the level?

The reason I ask is that, if you are cutting away ground on your side, hopefully you are not anywhere near any building foundations.

Also if the wall is about 4' high, is that also the difference in gound levels you are creating?

I'm guessing the ground slopes across at the moment wth no wall.

 

[mikebucks]

Hi Blagard the ground drops away on my side and has been cut slightly to accomodate the wall the drop is down to my side and there are buildings close to the boundary but one has just been built and is a timber building on a slab,they buiolt it knowing the drop was there.The other is a converted garage on a slab that was previosly there. There are no major "house " buildings close to the boundary.

 

[Static]

If these outbuildings are within a line of 45deg (in section going up) of your new retaining wall foundation base.. then you need to consider how you will support the ground during the construction of the wall..

Work out height diff between bottom of your wall foundation and the existing buildings and then distance between the outbuilding and your walls foundation.. if the distance between building and your footing is less than the height then you need to provide some temp works..

You really dont want to have to explain to your neighbour when his garage has slid down the bank into your garden..

 

[Blagard]

Hi mikebucks,

Static is pretty much right about the care needed when doing any work near other foundations. However, that alone may not be enough. By permanently cutting into the ground near an existing building you can cause the ground conditions to be affected locally and induce subsidence. e.g. clays drying out and shrinking.

So long as you are happy about the the relationship of any nearby buildings and the risk, then no problem. Each case needs to be viewed on it merits. "Heads up" done!