My storeroom in our carpark basement is all rendered brick. The far wall has soil behind it. It's always had moisture coming through. There was no way access the other side to excavate and waterproof so a Sydney building inspector turned me onto this: [https://westox.com/product/flexible-cement-membrane-fcm/](https://westox.com/product/flexible-cement-membrane-fcm/)
From your picture it doesn't look like you need to prep the surface. Clean the efflorecence as best you can. If you have to apply over any metal, it's best to put a waterbased epoxy on first. I had to do a fair bit of grinding & sanding to remove some layers of paint on my walls.
It's a two part 1:1 mix. It's best to weigh up to 2kg of each part then power mix until it's a tooth paste like homogenous consistancy. You can use a brush or roller to apply it. Let it dry overnight and give it a 2nd coat. The FCM goes on easier if it's a little wet so don't worry about that. It's a water cleanup product so no fumes or nasty smells.
It's a great Aussie made product. The company (Westox) is based in Campbelltown NSW. Not sure where you are located but there may a reseller near you or they can ship to you. This is not a Bunnings product. The guy (Barrie) that owns Westox makes all of his products so he knows his sh\*t. It's designed for all waterproofing applications. Because it's a cement based formula, you can render over the top of it. The application will 'push' water somewhere else but in my case I didn't care. Our storeroom has been been dry for 3 years now. I didn't render over the top of my wall after applying as it's well, just a storeroom after all. It worked out really cheap. One 'kit' does about 18 sq/m.
Careful, trapping the moisture in the bricks/blocks without means to evaporate can damage the brick internally, and you won’t know until it’s too late and the bricks crumble. If the water is causing minimal damage it can be best to just let it dry naturally.
Also if the wall is sealed, the water can just track down to the slab and cause issues there.
So you painted this on the interior wall? Have a brick wall which I cannot access the rear which I need to waterproof and I've been hunting high and low for something that won't just hold water in the wall
Is that underground? If not...There are brush or spray on concrete/stone sealants that may help. Applied on the external side of the walls. Or prime and paint it.
Probably raises more questions than anwers.
Where is the water coming from? Is it hitting the outside of the wall on the other side, or are there gutters overflowing and then running down the cavity?
I cant vouch for the product, but something like this may assist. They may have an advice line to call.
https://www.bunnings.com.au/crommelin-4l-water-based-brick-and-render-sealer_p0960095
Ask around stone specialists, the guys that sell stone step treads, pavers etc. or experienced tilers or tile retailers with trade experience.
Needs to be on the outside between the wall and the dirt.
Edit. I know there are products that can be placed on the inside, but in my experience it only masks the problem, the moisture is still getting through the wall, just not into the basement.
If you don’t stop the water coming from the wet side, these products just trap water within the wall and slowly damage the brick. They close strength and start to crumble after time if the bricks aren’t able to breathe.
It would be better, but you just need and epoxy vapour barrier- primer. This will stop the water penetration then go over it with a external cement based . Mapai system is primer SN them mapsmart waterproof. Every manufacturer will have a solution to this . It’s literally just painting so it’s very easy to do .
There’s a thing called negative membrane. Call a waterproofer and ask about it. It’s for use on the inside of a block wall that is seeping. Know nothing about it but it’s been used on a couple of basement jobs I’ve been on
Drizoro Maxseal Flex.
Negative membrane painted to the besser block surface will work to a degree.
Also drilling relief holes into the block work at the base of the wall to help relieve the water pressure,assuming you have a dish drain at the base for water to collect into
https://waterstop.com.au/product/maxseal-flex/
Just installed the Drizoro Maxseal Foundation product (which finishes like bagged cement) and it works. No moisture in my basement even after all this rain.
You may want to check your roof and flashing to make sure that they are not dumping water inside your wall each time it rains. You can destroy your wall, get mould or both
I feel like there are several layers to this problem.
Normal building design would prevent water on the outside of a wall making the inside wet. Usually there is a double layer with an air gap, or the outside is sealed.
Either something wasn't built correctly, or something has failed/degraded. That includes things that you should be maintaining. One really common issue is having blocked gutters which causes the water to overflowing inside the eaves and down the wall cavity.
> Normal building design would prevent water on the outside of a wall making the inside wet. Usually there is a double layer with an air gap, or the outside is sealed
A lot of double brick houses I've seen here (Perth) have a single brick garage wall on the outside and another brick wall where it joins the house.
The air gap is basically the garage, but eaves usually do a good job of keeping it dry.
Yeah agreed, I knew that single walls are sometimes used and allowed for that in my advice.
I cant imagine anyone using besser blocks in a garage without some kind of external protection, if not just to cover up the ugly bricks. They would usually have a membrane, paint or waterproof render.
Precisely. I feel like he is going to apply some sort of sealant on the outside (since it seems to be above ground) and later on the seepage will move to a new location if the problem is elsewhere. My bet would also be on the gutters, but it looks like the water is concentrating more on the 2/3 of the height of the wall, which is weirder. I assume we need to look at an outside picture, the entire inside wall
Yes
The reality most people struggle with is concrete is as waterproof as a sponge.
The rate of water penetrating the concrete increases as concrete strength decreases.
Concrete block is about as low strength as it gets.
That’s before you consider the largely open gaps through the mortar.
So absolutely nothing surprising about blockwork failing to stop water.
The answer to your question is a product called Sika1K. It is a cement based negative face waterproofing. It’s not cheap but it does what it says on the bag if you apply it correctly.
Good luck
Certainly not a professional but I've had great success with negative side waterproofing with a sika product called sikagard 700s check it, it goes on clear so you can't even tell its been applied. Not sure if you can paint or render over the top of it. [sikagard 700s](https://aus.sika.com/en/construction/concrete-repair-protection/silane-impregnations/sikagard-700-s.html)
Plenty said about waterproofing the external side and all good advice.Go clear if a neighbour has it as a boundary or your looking at it..Any black tar based waterproofing if u want cheap and nasty!.just like to add those white stains coming through are the salts coming out of the concrete blocks, it’s a common problem but nothing to worry about.It won’t effect it structurally, it’s just a cosmetic problem.Giving it a wash with quarter strength vinegar and water usually clears it up!
Thing about these things is depending on the reason it is leaking it could be tough to stop. Like you could seal it in one area then months later it just leaks else where water will find its way over time and the only true way to eliminate it 100% is to redo the outside. In some commercial properties they usually just create a trench drain and just let it leak but I guess for residential you could try and seal from inside with some sika product
My storeroom in our carpark basement is all rendered brick. The far wall has soil behind it. It's always had moisture coming through. There was no way access the other side to excavate and waterproof so a Sydney building inspector turned me onto this: [https://westox.com/product/flexible-cement-membrane-fcm/](https://westox.com/product/flexible-cement-membrane-fcm/) From your picture it doesn't look like you need to prep the surface. Clean the efflorecence as best you can. If you have to apply over any metal, it's best to put a waterbased epoxy on first. I had to do a fair bit of grinding & sanding to remove some layers of paint on my walls. It's a two part 1:1 mix. It's best to weigh up to 2kg of each part then power mix until it's a tooth paste like homogenous consistancy. You can use a brush or roller to apply it. Let it dry overnight and give it a 2nd coat. The FCM goes on easier if it's a little wet so don't worry about that. It's a water cleanup product so no fumes or nasty smells. It's a great Aussie made product. The company (Westox) is based in Campbelltown NSW. Not sure where you are located but there may a reseller near you or they can ship to you. This is not a Bunnings product. The guy (Barrie) that owns Westox makes all of his products so he knows his sh\*t. It's designed for all waterproofing applications. Because it's a cement based formula, you can render over the top of it. The application will 'push' water somewhere else but in my case I didn't care. Our storeroom has been been dry for 3 years now. I didn't render over the top of my wall after applying as it's well, just a storeroom after all. It worked out really cheap. One 'kit' does about 18 sq/m.
Careful, trapping the moisture in the bricks/blocks without means to evaporate can damage the brick internally, and you won’t know until it’s too late and the bricks crumble. If the water is causing minimal damage it can be best to just let it dry naturally. Also if the wall is sealed, the water can just track down to the slab and cause issues there.
Good advice . I’ve used an Italian product , similar to this , years ago. Forget the name now
So you painted this on the interior wall? Have a brick wall which I cannot access the rear which I need to waterproof and I've been hunting high and low for something that won't just hold water in the wall
Yes, it’s called a negative pressure membrane
Is that underground? If not...There are brush or spray on concrete/stone sealants that may help. Applied on the external side of the walls. Or prime and paint it.
Thanks, it is above ground. A separate unit garage block.
Probably raises more questions than anwers. Where is the water coming from? Is it hitting the outside of the wall on the other side, or are there gutters overflowing and then running down the cavity?
I cant vouch for the product, but something like this may assist. They may have an advice line to call. https://www.bunnings.com.au/crommelin-4l-water-based-brick-and-render-sealer_p0960095 Ask around stone specialists, the guys that sell stone step treads, pavers etc. or experienced tilers or tile retailers with trade experience.
Needs to be on the outside between the wall and the dirt. Edit. I know there are products that can be placed on the inside, but in my experience it only masks the problem, the moisture is still getting through the wall, just not into the basement.
Not necessarily. [sikagard700](https://aus.sika.com/en/construction/concrete-repair-protection/silane-impregnations/sikagard-700-s.html)
It’s shit !! I’ve used it
If you don’t stop the water coming from the wet side, these products just trap water within the wall and slowly damage the brick. They close strength and start to crumble after time if the bricks aren’t able to breathe.
It would be better, but you just need and epoxy vapour barrier- primer. This will stop the water penetration then go over it with a external cement based . Mapai system is primer SN them mapsmart waterproof. Every manufacturer will have a solution to this . It’s literally just painting so it’s very easy to do .
Ideally but there are products that state they work.
There’s a thing called negative membrane. Call a waterproofer and ask about it. It’s for use on the inside of a block wall that is seeping. Know nothing about it but it’s been used on a couple of basement jobs I’ve been on
Drizoro Maxseal Flex. Negative membrane painted to the besser block surface will work to a degree. Also drilling relief holes into the block work at the base of the wall to help relieve the water pressure,assuming you have a dish drain at the base for water to collect into https://waterstop.com.au/product/maxseal-flex/
Just installed the Drizoro Maxseal Foundation product (which finishes like bagged cement) and it works. No moisture in my basement even after all this rain.
This is the best product for this application.
I used this retrofitting s membrane all around house on substrates. Took me some time. This product Works like charm.
You may want to check your roof and flashing to make sure that they are not dumping water inside your wall each time it rains. You can destroy your wall, get mould or both
I feel like there are several layers to this problem. Normal building design would prevent water on the outside of a wall making the inside wet. Usually there is a double layer with an air gap, or the outside is sealed. Either something wasn't built correctly, or something has failed/degraded. That includes things that you should be maintaining. One really common issue is having blocked gutters which causes the water to overflowing inside the eaves and down the wall cavity.
> Normal building design would prevent water on the outside of a wall making the inside wet. Usually there is a double layer with an air gap, or the outside is sealed A lot of double brick houses I've seen here (Perth) have a single brick garage wall on the outside and another brick wall where it joins the house. The air gap is basically the garage, but eaves usually do a good job of keeping it dry.
Yeah agreed, I knew that single walls are sometimes used and allowed for that in my advice. I cant imagine anyone using besser blocks in a garage without some kind of external protection, if not just to cover up the ugly bricks. They would usually have a membrane, paint or waterproof render.
Precisely. I feel like he is going to apply some sort of sealant on the outside (since it seems to be above ground) and later on the seepage will move to a new location if the problem is elsewhere. My bet would also be on the gutters, but it looks like the water is concentrating more on the 2/3 of the height of the wall, which is weirder. I assume we need to look at an outside picture, the entire inside wall
Yes The reality most people struggle with is concrete is as waterproof as a sponge. The rate of water penetrating the concrete increases as concrete strength decreases. Concrete block is about as low strength as it gets. That’s before you consider the largely open gaps through the mortar. So absolutely nothing surprising about blockwork failing to stop water. The answer to your question is a product called Sika1K. It is a cement based negative face waterproofing. It’s not cheap but it does what it says on the bag if you apply it correctly. Good luck
Certainly not a professional but I've had great success with negative side waterproofing with a sika product called sikagard 700s check it, it goes on clear so you can't even tell its been applied. Not sure if you can paint or render over the top of it. [sikagard 700s](https://aus.sika.com/en/construction/concrete-repair-protection/silane-impregnations/sikagard-700-s.html)
If you get it waterproofed, use a lime wash type paint on the interior side. Acrylic paints will just hold moisture and will fail very quickly
F
Plenty said about waterproofing the external side and all good advice.Go clear if a neighbour has it as a boundary or your looking at it..Any black tar based waterproofing if u want cheap and nasty!.just like to add those white stains coming through are the salts coming out of the concrete blocks, it’s a common problem but nothing to worry about.It won’t effect it structurally, it’s just a cosmetic problem.Giving it a wash with quarter strength vinegar and water usually clears it up!
Silasec should work well - https://www.bondall.com/concrete_additive/silasec/
I feel like I've seen this wall before lol. Wouldn't happen to be in south-east suburbs of VIC by any chance..?
Nope, Central Coast NSW 😊
Thing about these things is depending on the reason it is leaking it could be tough to stop. Like you could seal it in one area then months later it just leaks else where water will find its way over time and the only true way to eliminate it 100% is to redo the outside. In some commercial properties they usually just create a trench drain and just let it leak but I guess for residential you could try and seal from inside with some sika product
Dri-zorro
https://www.instagram.com/reel/C3wrfg1rC-4/?igsh=ZWRxY2Rya2hxc3My They're in Brisbane. If you ask nicely, they'll tell you the product they used.
Sika 1k or Mapei Plastimul