# Forum Home Renovation Waterproofing  Bond breakers - are they necessary?

## LittleTommy

Hi All, 
I asked my tiler whether he is going to use bond breakers but he said waterproofing stuff he uses is great and very elastic once applied, so no bond breakers are needed. Is it correct? 
Thanks,
Roman

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## OBBob

> Hi All, 
> I asked my tiler whether he is going to use bond breakers but he said waterproofing stuff he uses is great and very elastic once applied, so no bond breakers are needed. Is it correct? 
> Thanks,
> Roman

  Isn't there a standard on this. I'd be a bit concerned about what he's proposing.

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## phild01

I would just let the tiler tile and get an accredited waterproofer in prior, especially for warranty.

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## METRIX

> Hi All, 
> I asked my tiler whether he is going to use bond breakers but he said waterproofing stuff he uses is great and very elastic once applied, so no bond breakers are needed. Is it correct? 
> Thanks,
> Roman

  No, your tiler is incorrect, Bond breakers are required, I used to do work for a builder who did not use bond breakers, I mentioned to him about them, and he looked at me like I spoke another language, wasn't interested. 
Bond breakers are part of a waterproofing system, as outlines in the BCA. 
I assume your tiles is not going to issue a waterproofing certificate as well ?

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## Pulse

class III highly elastic membranes can use a 12mm fillet of silicone or polyurethane as a bond breaker and not a 50mm wide band, maybe he means that?  
Sent from my iPhone using Tapatalk

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## phild01

I believe K10 only needs the silicone fillet
  ...yep it's class III. 
so is cromellin, but I still used the bond breakers.

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## METRIX

Silicon is acting as the bond breaker

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## phild01

> Silicon is acting as the bond breaker

  yes.

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## LittleTommy

> I would just let the tiler tile and get an accredited waterproofer in prior, especially for warranty.

  In our case the tiler would be doing waterproofing. He has a building license, I assume he is qualified to waterproof, or should I be concerned?

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## LittleTommy

> class III highly elastic membranes can use a 12mm fillet of silicone or polyurethane as a bond breaker and not a 50mm wide band, maybe he means that?

  It's quite possible, thanks for the hint! I'll ask him again on how exactly he is going to do it.

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## Watters

> or polyurethane as a bond breaker?

  Only if the polyurethane sealant is designed with bond breaker characteristics. Waterproof membrane will stick to polyurethanes such as Sikaflex 11fc in which case it won't be acting as a bond breaker. One way to tell is, if the polyurethane is paintable then it is unlikely to function as a bond breaker. 
Polyurethane with bond breaker characteristics is more durable than silicone, and, probably, less resistant to mould over time. Silicones often have fungicides in them but the fungicides don't last forever.   

> ...but I still used the bond breakers.

  Did you use something like this instead of silicone for the bond breaker?  http://www.crommelin.com.au/range/at...-bond-breaker/

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## phild01

> Only if the polyurethane sealant is designed with bond breaker characteristics. Waterproof membrane will stick to polyurethanes such as Sikaflex 11fc in which case it won't be acting as a bond breaker. One way to tell is, if the polyurethane is paintable then it is unlikely to function as a bond breaker. 
> Polyurethane with bond breaker characteristics is more durable than silicone, and, probably, less resistant to mould over time. Silicones often have fungicides in them but the fungicides don't last forever.  
> Did you use something like this instead of silicone for the bond breaker?  Reinforcing Bandage with Bond Breaker: Waterproofing: Crommelin

  Use silicone if bond breaking, not polyurethane, as the silicone is like teflon, nothing sticks. 
Yes used that type as a bond breaker as I used polyurethane.

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## Watters

> Use silicone if bond breaking, not polyurethane, as the silicone is like teflon, nothing sticks. 
> Yes used that type as a bond breaker as I used polyurethane.

  I guess if one wanted to really go to town with this you could put silicone on the joints AND use reinforcing bandage with integrated bond breaker tape. So, instead of ordering a whopper you go for the angus beef.... 
And if you put this stuff on top of the reinforced bandage you would have a triple burger:  https://www.bunnings.com.au/crommeli...abric_p1070499 
Only kidding (regarding the liquid reinforcing bandage, that is)....

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## METRIX

> Polyurethane with bond breaker characteristics is more durable than silicone, and, probably, less resistant to mould over time. Silicones often have fungicides in them but the fungicides don't last forever.

  Any decent silicon is extremely durable and will have a guaranteed life of minimum 25 years, mould should not even come into the equation, if it is then you either haven't done the waterproofing correctly, or you have no faith in how you are doing the waterproofing. 
The silicon is on two dry substrates, behind a waterproof bandage, under a screed protected forever, it's not rocket science. 
What you should be concentrating on is the following. 
Is the silicon compatible with the waterproofing membrane your using, ie is the silicon neutral cure or acidic cure
How thick are you applying the silicon as a bond breaker - 13mm is recommended
Are you applying enough membrane per coat to perform it's job as specified usually 1.5mm thickness is minimum  
I would simply give the silicon a miss and use a professional bandage with inbuilt bond breaker, problem solved.

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## Watters

> Any decent silicon

  Which brands? Selleys wet area silicone, for example?   

> The silicon is on two dry substrates, behind a waterproof bandage, under a screed protected forever, it's not rocket science.

  Assuming waterproofing below the screed is the case, if you have the following layers: 
Tiles
Tile adhesive
Screed
Waterproofing
Bandage
Silicone
Tile underlay
Particleboard 
Over time, could moisture potentially seep up from damp air under the subfloor through the particleboard and into the tile underlay and thereby reach the silicone from underneath?   

> I would simply give the silicon a miss and use a professional bandage with inbuilt bond breaker, problem solved.

  Or you could do both...Sometimes you can get small wrinkles in the bandage with inbuilt bond breaker after applying the membrane if you are not careful. Having silicone there as well is extra insurance...

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## METRIX

> Which brands? Selleys wet area silicone, for example?

  Selleys have a lot of good silicon's, some of their latest offerings are very advanced, ie: Storm, is able to stick to surfaces which have running water over them and seal them instantly, great if you have a leaking skylight or similar.
Most of their products come with a 25 year guarantee if applied correctly 
Sika also have a lot of good stuff, but like anything as I have said on here before, if you are unsure speak to the manufacturer of the product for example your membrane manufacturer, ask THEM what THEY recommend   

> Assuming waterproofing below the screed is the case, if you have the following layers: 
> Tiles
> Tile adhesive
> Screed
> Waterproofing
> Bandage
> Silicone
> Tile underlay
> Particleboard 
> Over time, could moisture potentially seep up from damp air under the subfloor through the particleboard and into the tile underlay and thereby reach the silicone from underneath?

  Damp air does not seep, water seeps, and it seeps down due to gravity, damp air can condense on a surface if the conditions are right, if you are concerned about this, then you have a bigger problem that needs dealing with that a bit of anti mould silicon is't going to fix, I would be more concerned about the YT flooring being stuffed from this magical anti gravity seeping. 
I know you have a water problem under this place, you should look at installing some sort of underfloor ventilation system if your current set-up is inadequate, again if this is a concern don;t worry about mouldy silicon, worry about the Termites which will be attracted to the moisture.   

> Or you could do both...Sometimes you can get small wrinkles in the bandage with inbuilt bond breaker after applying the membrane if you are not careful. Having silicone there as well is extra insurance...

  
Yes you can get wrinkles, because the product your using is crap, use a commercial / professional grade product with inbuilt silicon bond breaker, bypass the silicon and the rubbish DIY bandages sold at Bunnings.

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## Watters

RE Polyurethane, just to mention that it does have a few advantages over silicone. Should you ever have to (and I'm not saying anyone should do this at all), it is possible to put new polyurethane over old polyurethane. New silicone will never stick to old silicone. Polyurethane is also naturally resistant to mould whereas silicones need to have a fungicide added to it and the fungicide doesn't last forever. Polyurethane is also more durable than silicone. 
Two of the popular polyurethanes used are Sikapro and the Crommelin one.     

> if you are unsure speak to the manufacturer of the product for example your membrane manufacturer, ask THEM what THEY recommend

  Agree, yes.   

> I know you have a water problem under this place, you should look at installing some sort of underfloor ventilation system if your current set-up is inadequate, again if this is a concern don;t worry about mouldy silicon, worry about the Termites which will be attracted to the moisture.

  That's why I built the two slabs with drainage to stop water entering into the subfloor. The clay dirt is dry now. I also removed old builders wood waste and rubble from under the subfloor too. I mentioned it because others might want to think about this. Your comment about moisture potentially attracting termites is particularly relevant.    

> Yes you can get wrinkles, because the product your using is crap, use a commercial / professional grade product with inbuilt silicon bond breaker, bypass the silicon and the rubbish DIY bandages sold at Bunnings.

  The Crommelin bandages may not be the best but I have used them in enough showers to know they work although they are probably not the cheapest around. That said, for me, polyurethane with bond breaker on all joints, then polyestor reinforcing bandage (no bond breaker, although you could do this as well as the polyurethane BB) and waterproofing is the most effective way of doing things.

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## METRIX

> polyurethane with bond breaker on all joints, then polyestor reinforcing bandage  and waterproofing is the most effective way of doing things.

  Effective, by definition is they way of producing a desired result and yes your methoid described above is effective, but that method is not the most effective way of doing it, there are more effective / efficient methods available. 
Like anything there are many ways of doing something effectively, as long as the result works and it abides or exceeds any relevant standards then the method is fine.

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## Watters

> ....Like anything there are many ways of doing something effectively, as long as the result works and it abides or exceeds any relevant standards then the method is fine.

  Totally agree. 
Oh, another thing if anyone is thinking of using polyurethane, make sure it has fully cured before applying bandage and membrane. Why? Because polyurethane gives off gas bubbles as it is curing and you don't want that happening behind your membrane. 
Also, e.g. if using silicone, don't use acetic cure (not good for many membranes). Neutral cure is the go.

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