# Forum Home Renovation Retaining Walls  which waterproofing product to use

## tsteele

Hi all, 
I've had a bit of a search around here, but need some additional help on what product to use.  I have a core filled grey block retaining wall.  I never waterproofed this when it was first built (lesson learnt there), over 10 years ago, and for this amount of time it's been a plain grey block wall (which the wife never seems to forget telling me).  I'm in the very painful process now of digging out the partial fill that was placed behind the wall (including tree roots & concrete rubble), in a very confined space, digging all the way down to the bottom course so I can paint on a waterproofing product. The footing has 200mm tall nylex strip drain behind it, and I'm not going to touch that, so just getting to where I can just see the top of the footing & strip drain. And for overkill I'm going to add another line of 100mm ag just to make sure there's no problems with drainage because I'm never digging this again.   From what I've gathered, the easiest and most likely best product to use is a bitumen based paintable product.  Having a look at Bunnings, there's so many different brands, and I'm not sure which is best, or really does it really matter if they are all near enough the same.  They come in either 15L or 20L.
I'm looking at one of these: https://www.bunnings.com.au/gripset-...brane_p0960167 https://www.bunnings.com.au/sikatite...oofer_p0960531 https://www.bunnings.com.au/ormonoid...pound_p0964775 https://www.bunnings.com.au/crommeli...kseal_p0968096
there's also a Bondall product as well http://www.bondall.com/titerange-wat...umen-membrane/ 
I've read some previous reference to Gripset 51, but I think that is just called Gripset Betta now.    Has anyone has any experience with any of these, or something else they can suggest?
I was looking to apply 2 maybe 3 coats, where the 1st coat is thinned with water 1:1 ratio, and the additional coats straight from the container.  I have approx 30m to waterproof.
Thanks
Tim

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## METRIX

Any of the Bitumen based ones work fine, I have used the following and they all worked fine, not a big fan of some of the Gripset products, I prefer Crommelin.  
Biggest problem's you are going to find are to make sure you clean all dirt etc from the internal of the wall, wash it down before applying so you have a clean surface to work with, depending on how "WET" the inside of the wall currently is choosing a product may be limited or you will need to use additional products to overcome the wet wall. 
You will also need to let the wall dry out for some time to expel all the water caught in the wall's structure before applying any finishing coating on the outside, although you can use something like Gripset Damp Stop to overcome this but I would prefer to let the wall dry out. 
Crommelin recommend 1:5 ratio for the first coat Sika recommend 1:3 ratio. 
Crommelin recommend if the surface is not dry you need to apply dampstop first which is expensive, so go for the Sika product as it can be applied to damp surfaces, how damp ? you may need to call Sika and ask.

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## Oldsaltoz

And the bad news is you will have to dig down to the footings and apply a membrane or flashing covering the bottom of the wall and the top of the footing. 
I have used the Sikaflex BE. a Bitumin like product applied with a roller. (the wider the better). The first coat is thinned to ensure any tiny holes and fine cracks are primed so subsequent layers will stick better, The wall Must be moist before applying the thinned coat. 
Coats will bond to the wall by starting at the bottom after you have sealed the wall to footings joint, then work a section about a metre wide working from the bottom up so you can keep each run wet on wet at the joints. 
You need to apply 3 coats over the original thinned layer.  
To protect the wall after all areas have been sealed and dry, I find covering the surface with overlapping sheets of Core Flute. it's waterproof and will help protect the new waterproofing when backfilling and it's not expensive. Overlap like a tiled roof, Gaffer tape is Ok for holding the Core flute sheet overlapping joints. 
Andavagoodweekend.  :Smilie:

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## tsteele

Hi Metrix, I called Crommelin the other day to ask what’s the diff between their Blackseal and their Water Based Bitumen Paint, and they suggested the Blackseal as it’s more heavy duty and would dry faster then the Water Based one.  They are both water based, but they suggested Blackseal. They also suggested not to water it down. Adding water will just mean it needs longer to dry, and they suggested a good 4 days of dry weather. 
  I’ve so far used my gerni on the wall to clean it up.  There’s a few stains from roots that were growing along the wall that I can get a wire brush onto, otherwise it’s looking pretty clean and new looking.  The wall is dry at the moment as there’s been little rain of late, but unfortunately the forecast in Sydney over the coming week or two are a few showers.  I’ll call Sika and have a chat with them further.   
 Oldsaltoz, 
digging down to the footing, I’ve read in another thread where you suggested this, and I understand why, but it’s going to be too difficult to do. It’s been hard enough getting down to the 1st course on the footing. There’s no clearance in places as the wall was built very close to the excavated rock, just enough to get the strip drain behind the footing. The top of the footing has always been exposed so I can at least cover it with a membrane, just not the back of the footing. From what you’re saying with a thinned down coat of Sika and the wall needing to be wet, that might end up being the best option.  And I had planned on at least 3 coats, but with the thinned layer you’re saying that’s 4.  As for core flute, I was going to use Cordrain (expensive I know), but will create a larger gap between the wall and the backfill and help with drainage.  
 Thanks guys for the comments
 Tim

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## METRIX

> Hi Metrix, I called Crommelin the other day to ask what’s the diff between their Blackseal and their Water Based Bitumen Paint, and they suggested the Blackseal as it’s more heavy duty and would dry faster then the Water Based one.  They are both water based, but they suggested Blackseal. They also suggested not to water it down. Adding water will just mean it needs longer to dry, and they suggested a good 4 days of dry weather. 
>   I’
>  Tim

  You are only adding water to the first coat otherwise called a prime coat, you don't add it to the subsequent coats, it clearly states this in their documentation, they are on drugs. 
Blackseal recoat time is 1 hour, WBBP is 2-4 hours, they both need 72 hours to backfill and 7 days to cure, so much of a muchness, just means you can get more coats of blackseal on in shorter period, price is around the same so I would go for the quicker drying product, they both state 1st coat is watered down 1:5 (prime coat)

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## Oldsaltoz

> Oldsaltoz,  digging down to the footing, I’ve read in another thread where you suggested this, and I understand why, but it’s going to be too difficult to do. It’s been hard enough getting down to the 1st course on the footing. End Quote: Just checking for understanding, The bottom flashing is just an "L" shape, wall to the top of the footing.  
> The There’s no clearance in places as the wall was built very close to the excavated rock, just enough to get the strip drain behind the footing. The top of the footing has always been exposed so I can at least cover it with a membrane, just not the back of the footing. From what you’re saying with a thinned down coat of Sika and the wall needing to be wet, that might end up being the best option. And I had planned on at least 3 coats, but with the thinned layer you’re saying that’s 4. As for core flute, I was going to use Cordrain (expensive I know) but will create a larger gap between the wall and the backfill and help with drainage.

   
I find it best to install the wall to the top of footing joint first. Otherwise, you get fallout all over it when rolling the wall. If this done first and fall out will be a bonus, not a mess you clean up before waterproofing. 
Tip: Buy yourself some disposable coveralls, a hat with a reasonable brim and safety glasses.  :Smilie:

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## METRIX

> Tip: Buy yourself some disposable coveralls, a hat with a reasonable brim and safety glasses.

  Now here are some safety glasses  :Smilie:

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## tsteele

[QUOTE=Oldsaltoz;1074447]  _Just checking for understanding, The bottom flashing is just an "L" shape, wall to the top of the footing. _ 
I find it best to install the wall to the top of footing joint first. [/QUOTE] 
So this wall is already built, has been for 10+ years.  The back of the wall & footing is not L shaped, just straight.  So it's clear, this is the wall   
I can dig down to the top of the footing, just where I can see the strip drain.  I should be able to just cover the joint where the footing and the wall start, but near impossible to uncover all the rear of the footing.   On the front edge of the footing we have built in places some low wall garden beds (which I intend to completely waterproof inside, with drainage holes to let water out).   The red line is the waterproofing side of the retaining wall. The footing is built on sandstone, and behind the wall is 60% sandstone and only the top 40% is lose soil.

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## tsteele

> End Quote: Just checking for understanding, The bottom flashing is just an "L" shape, wall to the top of the footing.  
> I find it best to install the wall to the top of footing joint first. Otherwise, you get fallout all over it when rolling the wall. If this done first and fall out will be a bonus, not a mess you clean up before waterproofing. 
> Tip: Buy yourself some disposable coveralls, a hat with a reasonable brim and safety glasses.

  I had replied yesterday but for some reason it never appeared.  Just wanted to clarify that the wall is built already, and provide a drawing of the retaining wall and footing so you can see what I have.  I was a little confused with your comment "The bottom flashing is just an "L" shape, wall to the top of the footing. "

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## phild01

> I had replied yesterday but for some reason it never appeared.

  It's there now...strange glitch!

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## Oldsaltoz

> I had replied yesterday but for some reason it never appeared. Just wanted to clarify that the wall is built already, and provide a drawing of the retaining wall and footing so you can see what I have. I was a little confused with your comment "The bottom flashing is just an "L" shape, wall to the top of the footing. "

  No need to go to the bottom of the footing, it's just the joint between the block work and the footing you need to seal. Add a strip of membrane material by applying the thinned coat, then a standard coat followed by the membrane then the manufacturers recommended coat. Good luck and fair winds.  :Smilie:

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## tsteele

> No need to go to the bottom of the footing, it's just the joint between the block work and the footing you need to seal. Add a strip of membrane material by applying the thinned coat, then a standard coat followed by the membrane then the manufacturers recommended coat. Good luck and fair winds.

  I've just finished the excavation behind the wall, what a task that was. Not good for the back digging in such a confined space.  
I won't be able to add a strip of membrane as the nylex strip drain already installed comes to the top of the footing just below the mortar line. Gotta remember the wall has been in place for over 10 years and was partially backfilled.  So I will at least be able to apply the paint to cover the mortar line.  The only way to apply a membrane to correctly cover that joint, I'd have to completely dig out everything behind the footing (another 250-300mm down) back to rock and pull the strip drain away or out, which is just problematic.  So I didn't really want to have to remove the drain.  I'm hoping if I have the paint starting from the footing/block mortar line, along with a roll of 1m wide cordrain covering the bottom 1.0m of the 1.2m wall will help keep moisture off the wall.  I've also had to contend with roots from a neighbours tree. It's quite enjoyed the loose fill behind the wall, and in places it's squashed the drain somewhat and moved it away from the footing.   
I've gerni'ed the wall so it's as clean as it can be, just letting it dry now.   
Also, I couldn't find in the Sika notes where it says for Sikatite-BE to be applied to a moist wall. Crommelin do say the wall has to be dry, but Sika don't specify, well that I can see.

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## METRIX

> I've gerni'ed the wall so it's as clean as it can be, just letting it dry now.   
> Also, I couldn't find in the Sika notes where it says for Sikatite-BE to be applied to a moist wall. Crommelin do say the wall has to be dry, but Sika don't specify, well that I can see.

  
You might need to invest in a pair of those big glasses above  :Smilie:   :Smilie:   :Smilie:

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## tsteele

Don't need those glasses, I did see that line saying it can be applied to damp surfaces, I was more referring to Oldsaltoz saying "The wall Must be moist before applying the thinned coat." Must and may/can are different.

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## METRIX

Fair enough, I thought you might have liked a pair of those glasses, never know they might suit you,  
Sounds like I was wrong, 
I mentioned earlier Sika state it can be applied to a damp surface how damp ?  
I suggested you call them, as I always do if I have a specific product related query. 
After all they are the ones who make / distribute the product and have the answers to how it should / should not be applied good luck.

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## tsteele

while those glasses are indeed fashionable (for someone), I think my clear safety glasses are better  :Smilie:    Those glasses leave some large gaps around the eyes, and they are so big I'm sure I'd keep knocking off my head  :Biggrin:  
I'll call Sika today and discuss further with them.  I think Sikatite is going to be the best product to use given it can be applied to damp surfaces.  Sydney has some rain forecast for this coming weekend, and after that there's around 2 weeks of dry weather coming, so that's probably the best time to get it applied. 
However, before I apply the Sikatite my next hurdle is really that there's some large gaps in the mortar lines, and also that the mortar mix used to (poorly) build this wall was way too sandy (they skimped on the cement), so the gerni has removed a few mm of mortar in places (you can see that a little in those photos, the colour is very much of yellow brickie sand).  So they really need to be filled first I feel.  There's too many levels of wrong with this wall, I'm just trying to make sure this waterproofing is done as best I can so it never has to be done again.  I'll be good with all the extra drainage I've got to add behind, it's just getting the waterproofing applied correctly now. 
And I really do appreciate all your help  :Smilie:

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## tsteele

I called Sika today.  Sikatite BE can be applied to fairly well damp substrate which is good news. The substrate can be moist to touch and can still be applied.  Just as long as there's no running water over it... so for my application, the wall basically looks dry, but obviously there is some amount of non-visible moisture in the blocks & mortar (I used a basic moisture meter - actually a Crommelin branded one to show there is some moisture there).  That meter is not very accurate, but it was enough to show that the further down I go down the wall the more moisture since I gernied the wall.   Enough to prove to me that BlackSeal isn't the right product to use.
And to refill the mortar lines and gaps where there is missing mortar, as you have probably read in the datasheet,  I can make a mix of Sikatite BE with sand and cement and make a mortar/render to apply to the wall to make it flush in order to apply Sikatite BE better.  Just another pain that I have to go and patch up the mortar lines... across 30m of wall that's 1.2m tall.  :Annoyed:

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## tsteele

having just had another look at the mortar lines, most are not too bad and I could get away with just refilling the lines where the big gaps exist (completely missing mortar), or where the gerni has really chopped it out a little too much, and the rest where the mortar is 1-2mm below the face of the block it should be ok to just paint over with Sikatite.

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## Oldsaltoz

> having just had another look at the mortar lines, most are not too bad and I could get away with just refilling the lines where the big gaps exist (completely missing mortar), or where the gerni has really chopped it out a little too much, and the rest where the mortar is 1-2mm below the face of the block it should be ok to just paint over with Sikatite.

  G'day tsteele. 
I had the Sica rep on site one time and his advice was to wet the entire wall to ensure it was dust (or loose sand) free before applying the skim coat. The block work sucks up the surface water in no time and is ready to go. I would advise you state at the bottom of the wall by installing the joint between the block work and the footings. you can use an open weave cloth to strengthen the joint. It will get covered in fall out as you do the rest of the wall, so doing first avoids the cleanup later. 
Tip: If you keep the roller well loaded and work from the bottom up only, a dam of material will accumulate on the point of contact on the roller face, this will force the material into and gaps, you have to work from bottom to top about 3 rollers wide at a time and then another quick run over the last 3 roller widths to remove any runs, and repeat. Keep an eye on the areas you have completed as you go, looking for small areas that have a matt finish surrounded by wet shiny areas, this indicates the coat is drying before the area around it because the coat has been sucked in before the area around it, so it needs a bit more, extra layer. 
Good luck and fair winds.  :Smilie:

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## tsteele

After filling in alot of large gaps where mortar was either missing, or really chewed out from the gerni, I've now started on the primer coat.  Making the most of the dry Sydney weather, before rain start on Saturday. At least I know first hand how hard Sikatite is to remove after it's dried.  It's good stuff.

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## Oldsaltoz

> After filling in a lot of large gaps where mortar was either missing or really chewed out from the gerni, I've now started on the primer coat. Making the most of the dry Sydney weather, before rain start on Saturday. At least I know first hand how hard Sikatite is to remove after it's dried. It's good stuff.

  Ha Ha, Welcome to the black spot gang. Rubber gloves and bucket of clean water with loads of rags or thick paper towels, the sooner you remove it the better, I keep a damp cloth hanging out of my back pocket. 
Just keep that roller well loaded, it's not like you are painting, your coating so don't skimp on product.  :Smilie: 
The wide pink rollers at bunnies do a good job with this product.

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## Oldsaltoz

> After filling in a lot of large gaps where mortar was either missing or really chewed out from the gerni, I've now started on the primer coat. Making the most of the dry Sydney weather, before rain start on Saturday. At least I know first hand how hard Sikatite is to remove after it's dried. It's good stuff.

  Ha Ha, Welcome to the black spot gang. Rubber gloves and bucket of clean water with loads of rags or thick paper towels, the sooner you remove it the better, I keep a damp cloth hanging out of my back pocket. 
Just keep that roller well loaded, it's not like you are painting, your coating so don't skimp on product.  :Smilie: 
The wide pink rollers at bunnies do a good job with this product.

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## tsteele

> Ha Ha, Welcome to the black spot gang. Rubber gloves and bucket of clean water with loads of rags or thick paper towels, the sooner you remove it the better, I keep a damp cloth hanging out of my back pocket. 
> Just keep that roller well loaded, it's not like you are painting, your coating so don't skimp on product. 
> The wide pink rollers at bunnies do a good job with this product.

  black spot gang indeed!  I've kept a wet rag not far away.  I've started only with a 100mm brush so far for the 1st coat, as I wanted to make sure I coated all the mortar lines and the rough patched areas well, and to ensure any small holes in the block face are drowned.  I'll roll the 2nd coat, and given I've brushed the 1st one I will probably roll a 3rd if I think it needs it and to be on the safe side. Been really hard even with a brush to apply the raw sikatitle to the bottom, and in places can only just cover the footing/wall joint.

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## Oldsaltoz

> black spot gang indeed! I've kept a wet rag not far away. I've started only with a 100mm brush so far for the 1st coat, as I wanted to make sure I coated all the mortar lines and the rough patched areas well, and to ensure any small holes in the block face are drowned. I'll roll the 2nd coat, and given I've brushed the 1st one I will probably roll a 3rd if I think it needs it and to be on the safe side. Been really hard even with a brush to apply the raw sikatite to the bottom, and in places can only just cover the footing/wall joint.

   You will find that rolling from the bottom up (never roll down the wall) will push the product into any tiny holes, rolling down the wall will actually pull the material off the wall and accumulate under the roller and fall to the footing.  
Also, you should apply 3 top coats of the product over the first thinned primer coat. so 4 in all.
Good luck and fair winds.

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## tsteele

> You will find that rolling from the bottom up (never roll down the wall) will push the product into any tiny holes, rolling down the wall will actually pull the material off the wall and accumulate under the roller and fall to the footing.  
> Also, you should apply 3 top coats of the product over the first thinned primer coat. so 4 in all.
> Good luck and fair winds.

  Yup agreed on the 4 coats.  I've applied the thinned coat + 2 coats of the straight Sikatite, so 3 all up so far, with the 4th left to do after the weather fines back up next week.  I've used 2x15L tubs so far. I have another 15L tub and will make sure the 4th coat is a good coat, I'm not skimping on it by any means.  However it's almost impossible for me to go from bottom to top. I understand that's ideal, but the space between the wall and the earth behind is so confined, that in places I only have just on a foot width to place my feet parallel to the wall and then as little as 200mm space. The wall was built very close to the excavated rock face.  So I've mostly been going side to side, but once it's spread around in a small area I'm then working it in multiple directions to ensure every mortar line & hole is filled. And thanks for the tip on looking out for the areas that go black first as it's just an indication I've not applied enough Sikatite.  And as for any fall off hitting the footing, I don't think you understand how the footing is on the wall.  It's inline with the wall, so any fall off is simply hitting the dirt, so I'm trying to avoid any fall off.  If you look at the diagram I posted a few days ago, you'll see how the footing is not seen from the rear side I'm waterproofing.  Footing is only seen on the exposed part of the wall (the now rendered side of the wall).

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## Oldsaltoz

> Yup agreed on the 4 coats. I've applied the thinned coat + 2 coats of the straight Sikatite, so 3 all up so far, with the 4th left to do after the weather fines back up next week. I've used 2x15L tubs so far. I have another 15L tub and will make sure the 4th coat is a good coat, I'm not skimping on it by any means. However, it's almost impossible for me to go from bottom to top. I understand that's ideal, but the space between the wall and the earth behind is so confined, that in places I only have just on a foot width to place my feet parallel to the wall and then as little as 200mm space. The wall was built very close to the excavated rock face. So I've mostly been going side to side, but once it's spread around in a small area I'm then working it in multiple directions to ensure every mortar line & hole is filled. And thanks for the tip on looking out for the areas that go black first as it's just an indication I've not applied enough Sikatite. And as for any fall off hitting the footing, I don't think you understand how the footing is on the wall. It's in line with the wall, so any fall off is simply hitting the dirt, so I'm trying to avoid any fall off. If you look at the diagram I posted a few days ago, you'll see how the footing is not seen from the rear side I'm waterproofing. The footing is only seen on the exposed part of the wall (the now rendered side of the wall).

    Ok, I now understand the situation at the to base wall to footing layout. Have you considered a long handle on the roller and applying from the top and reaching down to the bottom with a loaded roller and pulling up the wall?

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## tsteele

> Ok, I now understand the situation at the to base wall to footing layout. Have you considered a long handle on the roller and applying from the top and reaching down to the bottom with a loaded roller and pulling up the wall?

  I have, but I don't think I have as much leverage and not enough pressure back on the wall, plus I wouldn't get to the very bottom. Even with the roller, I'm having to brush the bottom few cms of the 1st course & the footing mortar line (almost hands and knees) .  As hard as it's been doing it the way I've been rolling it (down behind the wall kneeling down to get to the bottom), it allows me to make sure the coating is done well and I'm not missing anything.  Even if this waterproofing done the day after the wall was built, it still would have been difficult (at least that's what I'm telling myself). I'm almost there, will just be glad when it's fully complete.  I'll give it a good 3-4 days before I start any backfill, but it does dry very fast, or as per the data sheet (and from Sika customer service) "trafficable after 24 hrs" .

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## Oldsaltoz

> I have, but I don't think I have as much leverage and not enough pressure back on the wall, plus I wouldn't get to the very bottom. Even with the roller, I'm having to brush the bottom few cms of the 1st course & the footing mortar line (almost hands and knees). As hard as it's been doing it the way I've been rolling it (down behind the wall kneeling down to get to the bottom), it allows me to make sure the coating is done well and I'm not missing anything. Even if this waterproofing is done the day after the wall was built, it still would have been difficult (at least that's what I'm telling myself). I'm almost there, will just be glad when it's fully complete. I'll give it a good 3-4 days before I start any backfill, but it does dry very fast, or as per the datasheet (and from Sika customer service) "trafficable after 24 hrs".

   There will be no problems with drying time. All the walls I did were done in a day. Mind you I had good access to almost all of them. I always used Coreflute to cover the walls, not too expensive, easy to handle and large enough to make a faster finish. The bottom sheet needs to cover the block/brick to footings joint. I would install the bottom sheets with a 250mm overlap to the next sheet, fixing the top edge with a suitable tape (Gaffer). When the first row is completed I added another tape along the vertical overlaps. The next layer has the same overlaps but starts with a half sheet so the sheet joints are not aligned and a 200mm overlap at the bottom of the sheet as well the ends. you should end up with tape on all joints and overlaps. Hope this helps.

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## tsteele

The waterproofing is all done, 4 coats all up.   I installed cordrain (bottom 1000mm) & some corflute (top 200mm) behind the wall, with additional 100mm ag pipe and heaps of 20mm recycled concrete (ANL re-agg) for drainage.  On the front of the wall, it's been rendered and undercoated so far.  However one more quick question if you have a minute.   We didn't render the entire wall, as parts of it will be covered with seating and low garden beds on the footing.  The inside of the garden beds I'm going to completely seal with Sikatite, but should I seal the sections where seating is going with Sikatite, or just seal and paint them, or can I just leave them untouched/exposed?  I think I need to seal them too, since Sikatite can be painted over. I just wasn't sure if leaving those sections as untouched grey block as a way of letting the wall dry out if water got it... but then on the flip side that's letting water in...hence I think I need to seal and paint over, before we install seating.

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## Oldsaltoz

> The waterproofing is all done, 4 coats all up. I installed cordrain (bottom 1000mm) & some corflute (top 200mm) behind the wall, with additional 100mm ag pipe and heaps of 20mm recycled concrete (ANL re-agg) for drainage. On the front of the wall, it's been rendered and undercoated so far. However one more quick question if you have a minute. We didn't render the entire wall, as parts of it will be covered with seating and low garden beds on the footing. The inside of the garden beds I'm going to completely seal with Sikatite, but should I seal the sections where seating is going with Sikatite, or just seal and paint them, or can I just leave them untouched/exposed? I think I need to seal them too since Sikatite can be painted over. I just wasn't sure if leaving those sections as the untouched grey block as a way of letting the wall dry out if water got it... but then on the flip side that's letting water in...hence I think I need to seal and paint over before we install seating.

    I would not waterproof any area on the other side of the wall, it will hold water a bleed out through the exposed side if it ever failed, very unlikely. Just paint it like the rest of the wall. Looks great by the way.

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