# Forum Home Renovation Bathrooms  Waterproofing shower tap penetrations

## carter237

Hi All, 
I'm in the process of a bathroom renovation using a builder currently up to the waterproofing. 
Now where the taps in the shower come through the villaboard there is quite a large punched out space. My builder tells me this does not need to be sealed at this point, only after the tiles have gone on. 
Everything I have read on here and can understand tells me that the taps should in fact be sealed to the villaboard, perhaps using a system like the tap penetration flange   
Any help would be much appreciated! 
Cheers

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## Pulse

Builder is wrong, not best practice at all. I'd use expanding foam if the gaps are large or backing rod and sikaflex. Then make sure the waterproofing is continuous from the wall sheet to the tap body. All depends if plumber has set noggin the right distance back. Just do it yourself before the waterproofed gets there. My bloody plasterer made holes with hammer, despite hole saw sitting on ground next to him. 
Cheers
pulse

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## Oldsaltoz

> Builder is wrong, not best practice at all. I'd use expanding foam if the gaps are large or backing rod and sikaflex. Then make sure the waterproofing is continuous from the wall sheet to the tap body. All depends if plumber has set noggin the right distance back. Just do it yourself before the waterproofed gets there. My bloody plaster made holes with hammer, despite hole saw sitting on ground next to him. 
> Cheers
> pulse

  + 1

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## carter237

Great. Thankyou for your input.  
Just another question. My shower is recessed with a 25mm step down, does this still need a waterstop angle? 
cheers

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## Oldsaltoz

Yes it will, also note it can be located inside the recess or more commonly just outside the recess. You will also need a need a water stop at the entry door and across the front of any built in storage cupboard. 
Good luck.  :Smilie:

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## barney118

I would ask a bathroom supplier which silicon to use. I understand you need one to match the waterproof membrane so there is no reaction.

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## Oldsaltoz

I would avoid the use of a silicon based sealant, primarily because it ever fails almost nothing will stick to what is left of the old silicon, 
Sikaflex 11FC is wat I have used for many years and never a problem, the FC indicates it's a Fast Curing sealant. 
Good luck.  :Smilie:

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## SlowMick

Oldsaltoz,  do you mean you use Sikaflex 11 FC under the membrane or to seal the tiles over the membrane as well?

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## Oldsaltoz

Use it ti seal the tap/mixer penetrations and at any all sheet joins including the wall to floor do this prior to adding the membrane. 
If you use it on the likes in the shower make sure you use soapy water or even better some Acetone. DO NOT wet you finger with spit to smooth it, the enzimes will cause the sealant to yellow. 
Good luck.  :Smilie:

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