# Forum Home Renovation Retaining Walls  Sealing bricks inside retaining wall

## Green1

We have just finished a brick retaining wall (pic attached) and all I have to do is put in an Ag drain and backfill, then paint the front (it's bagged on the front).   
I'm told it's best to seal it on the inside and am tossing up over plastic or a painted on sealer. Can anyone recommend a good paint on sealer? I have about 100mm or more in some places between back of wall and existing garden soil so figure I can get a roller down there without too much trouble. The wall varies in height, up to 900mm at highest. 
Any suggestions re the sealer greatly appreciated

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## seriph1

bloody nice wall dude! Does it have plenty of weep holes? Personally, I'd get professional advice on sealing it as it seems to me that if it was sealed, the water could build up behind it and would find its way through eventually anyway, damaging the brick through keeping it damp all the time  -  but I am NO expert on such things!

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## Green1

Hi Steve. Thanks, we are really pleased with it after months of looking at dirt! There are no weep holes, after advice from the brickie who did the wall and my Brother (plumber) . Plus I don't want it draining onto pavers (to come) or into the pool. I have openings into stormwater at both ends of the wall and will be running ag drainage right around the back of the wall, but want to keep the wall dry by sealing it.

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## Batpig

Dear Green, 
Whoever's given the advice about sealing the rear of the wall was probably thinking about the possibility of the paint wanting to peel off due to moisture getting at it from behind, but there's another very good reason to do so that I will talk about later. Firstly though, regarding the paint wanting to peel, have you thought about maybe "staining" the bagged cement render with some sort of oxide product instead? 
At any rate, instead of a paint-on sealer, I wonder if you could kill two birds with one stone by using one of those Vertical Drainage Sheets (eg. Nylex "Cordrain") instead of a sealer and drainage gravel: http://www.maccaferri.com.au/wa.asp?...&idDetails=121
You will still need an Ag drain in a sock at the bottom, though, to carry the water away. 
These Drainage Sheets are generally meant to replace gravel. They are a thin plastic egg-cratey-like sheet that lets moisture in through a filter cloth on one face. They go in hard up against the rear of a retaining wall. The only thing is, you'll have to check whether the brand and type of Sheet you end up getting interested in, is actually impermeable (ie. no holes) on the face that would go against the back of the retaining wall, so that it didn't let water go right through it into the brick. If it was impermeable, then I imagine you could seal it against the wall just along the sheet's top, bottom, and abutting edges, with something like a bitumen-like paste, and no water should then get in between it and the wall. The sheet is about $12/m2 from memory, and a whole lot easier to lug around than barrow loads of gravel. 
The other comment I might make is that your wall appears to be only about 230mm thick, going by the capping course on top of it. That would leave only about 10mm in the middle for reinforcement... I certainly hope it's reinforced!.. Anyway, with so little concrete cover around the steel reinforcement, and with bricks being as porous as they are, moisture will go through the bricks and get to the reo and rust it out if you don't seal the back of the wall. So one way or another, you'll have to keep moisture off the back of the wall. 
Anyway, see how you go. 
Best Wishes,
Batpig.

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## Green1

THanks Batpig - that product is very interesting - as you say could achieve two things at once. I have not seen or heard of this before.  
The wall is reinforced with starter bars in the footing, between two skins of brick (see pic) this was then obviously filled with concrete.This part is therefore about 450mm thick and has the steel . This was only done on the back section where it is 900mm high (incl. cap) and there is a long straight stretch. The rest of the wall is much less in height and there are some 90deg corners to also add strength. It all has 500mm deep footings with plenty of steel in there. Our block is mainly shale which was great fun to dig out for the footing (NOT!!) but means it is a good foundation so I don't think it will go anywhere. 
Cheers

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## Batpig

> Our block is mainly shale which was great fun to dig out for the footing (NOT!!) but means it is a good foundation so I don't think it will go anywhere.

  Dear Green, 
Just by the by for the sake of future forumites researching the subject, a rocky foundation can be both good and bad. Good, because your wall obviously can't turn over by the front going downwards into the ground. Bad, because if your concretor decides that the foundation is so good that you don't really need the footing to be as thick as what's on the design, the wall could still turn over due to the back of the footing lifting up because the soil pressure behind the wall is not being counteracted by the full weight of the footing as designed. Depends a lot obviously on what your backfill is like - if the backfill was also solid rock, you should be okay... 
Sorry to have sidetracked your thread with the talk about the Drainage Sheet. I'm sure you'd also like to hear from anyone who can suggest a paint-on tanker/sealer. Any takers guys? 
Best Wishes,
Batpig.

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## varpy

I've used a waterbased bituminous compound called Gripset 51. Sticks like the proverbial and that goes for skin and clothing too. Used it on leaking concrete ponds, gal rainwater tanks and mixed in a mortar slurry for a waterproof deck. The latter was a miserable failure, but the others worked out awright. 
Use a cheap roller and chuck it at the end of the job. (along with your clothes, hair, boots and any friendly white furry creature that has inadvertantly ambled by)   :Smilie:  
also tagged that drainage sheet batpig - good bit of gear there.....

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## Green1

Thanks Varpy - that's the sort of stuff I was after. I'll check out Bunnings and local building supplies for it. The product Batpig has suggested also sounds very interesting, I'll compare the costs though I think the roll on stuff will be cheaper. 
Re the footing Batpig, I'm sure you know one of the benefits of doing something yourself is you know it's done right.... After much research and suggestions from our brickie plus our designer (he's an architect not an engineer but knew a bit) I dug the footing myself with significant help from my F-in-law (yeh he is 70 odd but he volunteered and kept turning up - even when I tried to start early without him he was on to my ploy!!)  so I know it's deep enough. Also I put in the steel myself and with the help of the aforementioned family member and a couple of mates barrowed and worked the concrete. So am confident about the footing. Got in a good brickie for the wall though!!

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