How to build a Retaining Wall ?

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dj01

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Need to have a retining wall built to divide two different levels in the garden. Wall will be aprox. 5ft high and 20ft long with a soil bank behind it. Soil is not very sticky but it's not very dry either. The wall will be curved rather than straight.

What's the best way to build this type wall correctly? Should I use 4 inch blocks on flat with pillars built into the wall for strenght? Should concrete be poured in behind the wall in stages for support? I know weep holes will be needed to allow water escape through the wall.

Advice from anyone with expericence of building such walls would be appreciated.
 
Which way are you planning the curve?
A gravity wall system might work out better unless you are building the blockwork yourself.
 
Hi Sconhome

Its similar to a slim S shape. No getting the wall built. I ideally want a straight wall to maximize use of space, so trying to find out how it should be built with traditional blockwork if possible.

thanks
 
A block retaining wall will not give you the same strength as a reinforced mass concrete wall and, surprisingly, there is not much of a difference in the cost. A wall of that heighth would require 6" blocks and piers. With regard to weepholes, these often, if not always, become very unsightly over time. What we usually do is to lay a land drainage pipe at the rear of the wall, surrounded with gravel (similar to a french drain) and with each and tied into the surface water drainage.
 
Considering the height of the wall, you should really get it designed properly - if you don't put up a proper wall, it could over time collapse on top of, God forbid, kids, and also, if you want to sell on, this might be a sticking point.

Certainly strikes me that one layer of block would be nowhere near enough. The fact the soil is not very dry will put a lot of pressure on the back of the wall, even with weepholes as these can clog and block.
 
Try using an icf system tied onto a slab poured infront of the wall that will be overlaid with soil. this will save on the excavation and the overturning moments will be balanced by the horizontal slab. ICF will be a cheap formwok system as you could try and use some of their outdated blocks that provide high U values.
 
CharlieR said:
Try using an icf system tied onto a slab poured infront of the wall that will be overlaid with soil. this will save on the excavation and the overturning moments will be balanced by the horizontal slab. ICF will be a cheap formwok system as you could try and use some of their outdated blocks that provide high U values.
Click to expand...
 
CharlieR said:
Try using an icf system tied onto a slab poured infront of the wall that will be overlaid with soil. this will save on the excavation and the overturning moments will be balanced by the horizontal slab. ICF will be a cheap formwok system as you could try and use some of their outdated blocks that provide high U values.
Click to expand...

No offence CharlieR, but why would one need any u-value for a retaining wall?

OP, if you are more interested in a block wall, then you would probably require 450mm, i.e., a double course of standard blocks, up to a certain heighth at least. If you are trying to maximize space, you would achieve a stronger wall with 250mm re-inforced mass concrete.
 
Dont build with blocks. Use timber crib,modular blocksystem,soil panels,or Permapanels or similar. Latter are timber but may have height limitation. Google Retaining Walls and you find companies in Ireland who will design and install suitable systems. Remember if you build single wall( rather than stepped) you will require fall protection at top.
 
Thanks for all the suggestions. Am trying to build the wall as cheaply as possible, but obviousley the first priority is that it's done correctly. Am meeting with blocklayer this week to go through it. Hoping that 4 inch blocks on flat with piers built in will be sufficient, as I still think pouring a mass concrete wall will be a more expensive option.
 
If you are building with blockwork you might have to start with wall being 450mm thick at bottom changing to 315 and 215mm thick at top. Like Alfie said getting some professional advice might be a good start.
 
You should not be asking a blocklayer to design a 5 ft high retaining wall for you. You need input from and engineer or from company specialising in design/build of retaining structures. Phi Ireland is one such company and there are a number of similar. I would not consider unreinforced blockwork suitable medium for your project. Blockwork would work if you instead build as two stepped half height walls. I am by the way a retired Chartered Engineer.
 
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