# Forum Home Renovation Brickwork  Brick retaining wall core fill

## brydon

Hey, 3rd year BL'ing apprentice here, first solo project. 
I have a 10m x 350mm x 430mm brick wall that I want to core fill. 
Once it has been filled I'll be stepping the wall in to 230mm for three courses, then a header course. The wall will be .8m high. 
What type of concrete mix do I need to use? 
Here's a picture. 
Thanks.

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## cherub65

Hi Brydon, 
               Welcome aboard 
With the method you have chosen you should have rods from footing to finished height of wall (minus header) then lay horizontal bars while the wall goes up. The wall would not normally step in, core filled with a standard mix for that height 1 cement/ 2 sand/ 3 blue metal 10mm max 
Personally would have bricked the whole wall, 350mm x 5 courses then 230mm. Weep holes every 600mm

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## PeteV

you can usually get a 7mm stone mix from trade outlets. the 5-1 mix that cherub is suggesting is a waterproof mix which can also be known to shrink... i'd probably be inclined to use a 6-1 mix. for the small amount that you need, hand mixing is the way to go, just make sure you do it in layers... fill a course and a half at a time, making your way down the wall. once you get to the end, start again. hope this helps!

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## brydon

Cheers, guys.   

> Hi Brydon, 
> Welcome aboard 
> With the method you have chosen you should have rods from footing to finished height of wall (minus header) then lay horizontal bars while the wall goes up. The wall would not normally step in, core filled with a standard mix for that height 1 cement/ 2 sand/ 3 blue metal 10mm max 
> Personally would have bricked the whole wall, 350mm x 5 courses then 230mm. Weep holes every 600mm

  Yeh, I would have bricked it inside but I only have just enough bricks for the wall.

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## brydon

Forgot to ask. Where should the weepholes be and how do they work through a cavity, or do I start them at the 230 course?

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## PeteV

what is the wall going to be used for? garden retaining wall, or some sort of structural wall for a new building?

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## brydon

Just a retaining wall, not going to be supporting anything. (except dirt)

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## PeteV

ideally, i'd run an aggi line behind the wall which taps into a stormwater point and have no weep holes. you will have to tank the wall though. alternatively, you could punch through some conduit at the very base of the wall to use as weep holes, as cherub suggested at 600mm centres. keep in mind that using this method may stain the surface at the bottom of the wall if you have paving or concrete up against it. hope this helps!

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## brydon

> ideally, i'd run an aggi line behind the wall which taps into a stormwater point and have no weep holes. you will have to tank the wall though. alternatively, you could punch through some conduit at the very base of the wall to use as weep holes, as cherub suggested at 600mm centres. keep in mind that using this method may stain the surface at the bottom of the wall if you have paving or concrete up against it. hope this helps!

  Yeh, originally I was going to drill through and put a few copper pipes through the wall but thought an aggi pipe would be enough. By tanking the wall do you meen waterproofing it?

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## PeteV

yeah, it's like a black bitumen stuff that you roll onto the back of the wall... it has to roll down onto a clean footing too approx 200mm. a good trick i learn't was to sit the tanking bucket in a bigger bucket/wheelbarrow full of hot water. it makes it heaps easier to roll on! you'll probably wanna wait until al your bricks are in before you start that too. hope this helps!

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## brydon

Yeh, thought so. Thanks a lot for your help, man!

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## PeteV

no probs mate! brickwork looks real neat for a tradesman let alone a third year! keep up the good work!

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## Master Splinter

Dead giveaway that he's an apprentice - not enough empty stubbies around!   
If it has a good soild footing, it may be worthwhile drilling some holes into it and pounding in some reo bar before filling - I've seen the occasional retaining wall that has shifted off its footing because of the pressure on it.  (Gives you an excuse to buy a rotary hammer, too....)

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## PeteV

it kinda looks like he may have used star pickets as starter bars... there is something in the cavity with grey tape wrapped around the top...

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## brydon

> Dead giveaway that he's an apprentice

  Damn, you. When I read that I thought, OH **** what have I done wrong?! Haha.   

> it kinda looks like he may have used star pickets as starter bars... there is something in the cavity with grey tape wrapped around the top...

  Nah, they're reo bars; wrapped 'em up so no one would fall on them. There are two horizontal bars running the whole wall too, I hadn't put the top one in yet when I took the pic, though.

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## Gaza

dam nice job, 
funny that you ask a forum not your boss how to do stuff.

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## PeteV

could it be a cashy that the bossman doesn't approve of???

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## brydon

> dam nice job, 
> funny that you ask a forum not your boss how to do stuff.

  I would but I left my boss after I found out he wasn't doing things he was legally required to do...so I have none atm.

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## PeteV

whereabouts in melb are you?

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## brydon

> whereabouts in melb are you?

  Mooroolbark. In between Cryodon and Lilydale. I would of got a job by now just I've been lazy with getting my license, going for my test on the 25th so I should be fine once I get it. Cheers.

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## Master Splinter

Actually, the real giveaway is that the clamps aren't all rusty and covered in old mortar droppings, and they're not bent from having a rusty old hammer used to loosen them!

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## intertd6

A good thing to remember is to always leave cleanouts so you can wash & clean the mud from out of the core of any retaining wall. From memory there are designs for this type of retaining wall in the AS concrete footings & slabs.
regards inter

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## brydon

Here's the finished pic for anyone that cares.

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## Master Splinter

Needs more beer cans!

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## Bloss

> no probs mate! brickwork looks real neat for a tradesman let alone a third year! keep up the good work!

   :What he said:

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