# Forum Home Renovation Bathrooms  Waterproof membrane and silicone bond breaker advice

## Raidenx

Hi all,  
I am waterproofing my upstairs on suite bathroom. 
I just ran a 14mm bead of silicone in the wall/wall and wall/floor junctions and around the puddle flange. My wall is brick with cement render and floor is cement screed on a solid concrete slab.  
My concern is will waterproof membrane stick on the silicone when it's cured? 
I am not sure if I did it right with putting silicone into the small holes in the screed and afraid the waterproof membrane will not stick on the silicone. 
It is Sika neutral cure silicone and RLA dry flex pump waterproof membrane. I will be using all RLA products Universal primer, Dryflex Pump and Rubber modified tile adhesive. 
I will be priming the the entire floor and shower area using RLA Universal Primer green stuff mixed with 1:4 water as suggested by tile shop.  
I plan to do 3 coats waterproof and first coat straight onto of the shower area and entire floor in the bathroom and waterproof straight onto the silicone joints. 
One the 2nd coat I will apply fibre bandage in the wall/wall and floor/wall Junction. And 3rd coat for extra security. I know about different directions on each coats.  
My concern is also I went over board with the silicone around the joints and puddle flange and when I was shaping the corner bead it went over too much because I put on big bead so I just smeared the silicone over and wiped off as much with my fingers to make it as thin as possible.  See photos with the dark areas around the corner beads.  I also put silicone inside the puddle flange joints with the p trap so it'll stop the rising water in case there is a blockage etc and silicone at the edge of the puddle flange and I had excessive so I smeared around and all over the plastic flange. 
Will polyurethane waterproof membrane stick on silicone? I am worried if it doesn't the tiles will not stick on properly especially around puddle flange and tile could lift.

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## Raidenx

Closer look of the shower floor area. 
 All the shiny relections are from the silicon smears that was wiped off when I was forming the 14mm beading in the corner and it was a really messy job. I think the worst part of the kitchen and bathroom renovation is the siliconing.   
Should I put fibre bandage all around wall/wall, Wall/floor and wrap over the shower hob as well?
Do you think it's necessary to put fibre bandage around the mixer spout outlet too?

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## Skinah

> My concern is will waterproof membrane stick on the silicone when it's cured?  
> I plan to do 3 coats waterproof and first coat straight onto of the shower area and entire floor in the bathroom and waterproof straight onto the silicone joints. 
> One the 2nd coat I will apply fibre bandage in the wall/wall and floor/wall Junction. And 3rd coat for extra security. I know about different directions on each coats.

  No, membrane and most things will not stick to silicon. This is why people on this forum recommend a Polyurthane to be used instead like sikaflex 11FC. Buy it in a sausage format as you will need a lot and you save buying it in that format. Bunnings have a $12 gun which you will pay off doing the job u just did.  
Silicon can be used, it just makes your life harder as your about to find out. Your job looks fine don't stress just apply the bandage on your FIRST coat after doing any priming that the membrane requires. Make sure the bandage is saturated on the rear with the membrane before laying it. Wait for that to dry and then do your other layers as per recommendations for the membrane. Download their installation guide and check youtube for videos for your brand and type of membrane. 
Where you put silicon, even a thin smear will allow the membrane to lift and move as this is what you want when you put a bond breaker down. Your tiles will be larger and will not only be stuck to those areas so don't stress unless your using small mosaic sized tiles. 
I used the crommelin membrane that the big shed sells. You mix this 50% with water for a priming coat so you don't need to buy multiple products. Watering it down allows it to soak further into cement sheet or concrete like yours to improve the holding power.

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## Skinah

> I think the worst part of the kitchen and bathroom renovation is the siliconing.

  You just don't know the tricks, its easy when you know how. Next time I'm using silicon I will take a video. 
Buy these. https://www.bunnings.com.au/paint-pa...r-set_p1660196
dip them in soapy water, scrap the extra silcon and then wipe on a rag and dip in soapy water and repeat. Dishwashing liquid in a 1:4 ratio with water. The rest of the tricks I would need to use a video for.

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## Raidenx

I regret not coming on this forum and  search earlier before I applied the silicone. Learn something new everyday. I usually used silicone but yesterday I rushed and made a big mess as you know it's fun working with silicone. Next time I will keep in mind to use Poly sausage instead.  
What's the best method of removing silicone smear form cement render which has wooden float finish? I got to remove the silicone from the plastic puddle flange, I am thinking of using wire brush and rotary wire brush.   

> No, membrane and most things will not stick to silicon. This is why people on this forum recommend a Polyurthane to be used instead like sikaflex 11FC. Buy it in a sausage format as you will need a lot and you save buying it in that format. Bunnings have a $12 gun which you will pay off doing the job u just did.  
> Silicon can be used, it just makes your life harder as your about to find out. Your job looks fine don't stress just apply the bandage on your FIRST coat after doing any priming that the membrane requires. Make sure the bandage is saturated on the rear with the membrane before laying it. Wait for that to dry and then do your other layers as per recommendations for the membrane. Download their installation guide and check youtube for videos for your brand and type of membrane. 
> Where you put silicon, even a thin smear will allow the membrane to lift and move as this is what you want when you put a bond breaker down. Your tiles will be larger and will not only be stuck to those areas so don't stress unless your using small mosaic sized tiles. 
> I used the crommelin membrane that the big shed sells. You mix this 50% with water for a priming coat so you don't need to buy multiple products. Watering it down allows it to soak further into cement sheet or concrete like yours to improve the holding power.

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## OBBob

> You just don't know the tricks, its easy when you know how. Next time I'm using silicon I will take a video. 
> Buy these. https://www.bunnings.com.au/paint-pa...r-set_p1660196
> dip them in soapy water, scrap the extra silcon and then wipe on a rag and dip in soapy water and repeat. Dishwashing liquid in a 1:4 ratio with water. The rest of the tricks I would need to use a video for.

  
Good tip! 
It's an actual job... people just do caulking for a living.   :Biggrin:    
To the OP...  
The biggest thing I learnt is not to lick your finger and smear the silicone, that's a sure way to get mould. 
Also, mechanical is probably the best way to remove it. You can get stripper solutions, which may help ensure it's completely gone?

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## Raidenx

> Good tip! 
> It's an actual job... people just do caulking for a living.     
> To the OP...  
> The biggest thing I learnt is not to lick your finger and smear the silicone, that's a sure way to get mould. 
> Also, mechanical is probably the best way to remove it. You can get stripper solutions, which may help ensure it's completely gone?

  Of all the work involving in renovations I hate silicone joints tile corners in bathrooms and then follow by painting door frames in oil base enamel and cleaning up them brushes. 
ok on a more serious note I used the exact shaping tool from Bunnings but I cut off the nozzle 3cm from the caulk gun and the whole was too big and produced a big beat and it went everywhere when I used the 14mm shaping tool and basically I rushed into finishing it. Can't rush a job that needs to be done right. Lesson learned.

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## Skinah

Mechanical will work but will be a pain, since it is screed try using a knife to cut where you want the removed silicon to stop peeling, then use a paint scraper to rub at it. Silicon will peel and hopefully stop where you placed the cut with the knife. The screed will wear away if you rub at it most likely and the last of the silicon will come out with some sand. Try an area out of the shower first to find what works as the silicon may want to keep peeling. Sand paper on the plastic flange say 60-80 grit. Roughing up the plastic will also help the membrane stick so scratch it up a small amount on purpose. 
Looking at the picture more at home I see a lot of silicon on the puddle flange and also it looks like you used it to fill up a hole? Bottom left of the puddle flange around 100mm away. I would not leave the flange like that, needs to be stripped back otherwise the membrane wont stick to the flange for the entire top of it. You need to paint membrane down into the flange 10mm. Just a small amount of silicon where the plastic meets the cement is all that is needed to allow movement. 5-10mm on concrete and 5-10mm on the plastic so the membrane can stretch over this section. If you can get all the silicon off then use the 11FC and not silicon.  
As mentioned the wall and floor corners look fine if your using tiles that are large enough to still have 80% of their area over non silicon areas. You can get wide bandage to cover the silicon if you feel it can be left as is.. https://www.bunnings.com.au/crommeli...abric_p1070269 
Good luck and hopefully the silicon comes away neatly.

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## Raidenx

> Mechanical will work but will be a pain, since it is screed try using a knife to cut where you want the removed silicon to stop peeling, then use a paint scraper to rub at it. Silicon will peel and hopefully stop where you placed the cut with the knife. The screed will wear away if you rub at it most likely and the last of the silicon will come out with some sand. Try an area out of the shower first to find what works as the silicon may want to keep peeling. Sand paper on the plastic flange say 60-80 grit. Roughing up the plastic will also help the membrane stick so scratch it up a small amount on purpose. 
> Looking at the picture more at home I see a lot of silicon on the puddle flange and also it looks like you used it to fill up a hole? Bottom left of the puddle flange around 100mm away. I would not leave the flange like that, needs to be stripped back otherwise the membrane wont stick to the flange for the entire top of it. You need to paint membrane down into the flange 10mm. Just a small amount of silicon where the plastic meets the cement is all that is needed to allow movement. 5-10mm on concrete and 5-10mm on the plastic so the membrane can stretch over this section. If you can get all the silicon off then use the 11FC and not silicon.  
> As mentioned the wall and floor corners look fine if your using tiles that are large enough to still have 80% of their area over non silicon areas. You can get wide bandage to cover the silicon if you feel it can be left as is.. https://www.bunnings.com.au/crommeli...abric_p1070269 
> Good luck and hopefully the silicon comes away neatly.

  Thanks mate that really give me good technique to remove the silicone off the screed and render. I will run it with stanley blade first and the scrape a bit of render off with the scraper and surly it'll come off. The wall isn't a big issue since I will be using 600mm x 300mm or 600 x 600 tiles so there will be extra grip form tile adhesive holding up the piece and a couple cm at the corner will not affect the tile being stuck on the wall. 
Yeah I filled up the hole with silicone. Good spotting. I will just dig it out and then fill it in with the waterproof membrane itself and should be fine and scrape and sand down the top of the flange and inside. I only realise after siliconing and came in my mind wait nothing sticks on silicone.  
Thanks for all the advice and I wanted to avoid using chemical removal methods which could leave residue.

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