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Shower floor waterproofing membranes / floor grate

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  1. #1
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    Question Shower floor waterproofing membranes / floor grate

    Hi All
    Currently near the end of a 2 x bathroom reno undertaken by a builder.
    Would be interested in peoples[thoughts on membrane waterproofing, particularly near the shower grates (see attached pics).

    The Bathrooms were essentially tanked appropriately with appropriate fall on the floor/screed.
    The tiler has finished with quality tiles, adhesive and grout, came up great, but looking over my pics im not sure about how the membrane will drain if it ever had too.
    What are the chances it will ever see water and are we going to have a failure down the track or am I worrying over nothing?

    Any thoughts or reccomendatipns appreciated!
    [/SIZE]screenshot_20220507_164726.jpgscreenshot_20220507_164749_com.android.gallery3d.jpgscreenshot_20220507_161149_com.android.gallery3d.jpg

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    I don’t get what you are showing us. Was the waterproofing membrane laid down with the floor wastes in place ?

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    Arron yes floor wastes in place and then waterproofing. There doesn't seem to be any puddle flange or membrane drainage.

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    Thanks. Listening to the waterproofer who did our bathrooms recently, it sounded like the most important thing was that the waterproofing was continuous under the waste and down into the first few cms of the waste pipe.

    I don’t understand the concept of modern waterproofing however. How is drainage across a membrane supposed to occur if you have a quality tiling job and therefore 95% plus coverage of glue under the tiles? How does the water flow through that?

    Also, wouldn’t the puddle flange be below the screed and therefore not visible? Our puddle flanges are set into the fibre cement subfloor to accomodate drainage across the waterproofing below the screed.

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    Thanks Aaron. Looks like our waterproofing doesn't go down to waste. I have also found they have used standard plaster in wet area walls. It has been waterproofed but this is not to standards. As for the floor membrane the way I've been told,moisture can still get through grout eventually. If no whereto go it results in mould/dew floor build up. I have tiled bathrooms I am now in major concerns over with our builder!

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    My knowledge is pretty basic. Hopefully someone more knowledgeable will come along shortly, although I’ve found you don’t get much response to waterproofing questions on this forum and there isn’t a waterproofer or ex-waterproofer prepared to answer regularly.

    What I’ve been told about tiling is to regard it as porous - immediately it is done - and you won’t go wrong.
    My comment about 95% glue coverage was that I don’t understand how it is supposed to make its way to the waste, once it has penetrated the grout, with a near continuous film of waterproof adhesive blocking the way? Thus I wonder just how well undertile drainage works, or has ever worked?

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    Hi Reno,

    No expert but here goes based on my experience and whats detailed in the standards...which are a "bare minimum" requirement.

    1. Standard plaster is definitly not to the Aus3740 standards as per section 3 - 3.3.3
    2. Liquid membrane should be applied to the puddle flange as a minimum. The puddle flange should be recessed into the substrate and not protude above it. section 4.3 (b)
    3. Liquid membrane can be applied above or below the screed as per min standard or both but if you go onto the Gripset Utube site, their preference is if you are only going to apply 1 membrane, then under the screed is preferred. Section 4.2 Membrane installation for tile bed or screed

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    There is a wet area plasterboard, although 6mm Villaboard is prefered. The pictures are useless for a comment, they do not show enough of the story and the shower grate hides what has gone on around that connection.

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    Quote Originally Posted by RenoJoe View Post
    I have also found they have used standard plaster in wet area walls.
    No one in their right mind is going to use standard plasterboard in a bathroom so I assume you might be talking about the plaster basecoat. Normal basecoat is not a problem if it is used under tiling and it gets waterproofed anyway.

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    JohnC i did my best at snapping photos during the works.
    I just crawled under the house and got these pics. all is see is a screw on waste connection to shower grates.
    Attached Thumbnails Attached Thumbnails img_20220520_162014.jpg   img_20220520_161731.jpg  

  11. #11
    1K Club Member Pulse's Avatar
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    Default Shower floor waterproofing membranes / floor grate

    Iím no expert but that is not right, they have waterproofed into the shower linear grate only. Normally the floor is fully waterproofed onto the puddle flange and the grate just sits there in tile glue, water the the screed and glue runs under the grate, into the waste. Iíd take lots of photos and get an expert in. Like this example:


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    Thatís an excellent diagram Pulse. Thanks for that. I wish I had an equally good diagram for cases where you do waterproofing both above and below the screed.

    RenoJoe, I assumed originally your floor was compressed fibro (scyon etc) but looking at it from underneath it looks like fibreboard (yellowtongue). What exactly is the floor?

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    Thanks pulse. Getting an inspection report it's the only way fwd. Arron the floor is timber on stumps. Fibreboard on shower floor was apparently waterproofed screeded then waterproofed.

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    Quote Originally Posted by RenoJoe View Post
    Thanks pulse. Getting an inspection report it's the only way fwd. Arron the floor is timber on stumps. Fibreboard on shower floor was apparently waterproofed screeded then waterproofed.
    Ok, so you have waterproofing both above and below the screed. I didn’t realise that and it changes things.

    My understanding (and beware my limited experience) is that the bottom waterproofing should be continuous down into the puddle flange and down into the top of the waste pipe. The top waterproofing, where there is also bottom waterproofing done, should not go down into the pipe as it would then encapsulate the screed, so if it ever got wet it would have no way to dry. Therefore I would expect the top waterproofing to seal off against the floor wastes (just as it does with upstanding pipes like vanity and toilet drainage pipes). There should probably be bond breakers involved here as well, probably taking the form of silicon around the wastes but below the waterproofing. Of course you wouldn’t be able to see the puddle flange, or know if it has been waterproofed correctly because it is below the screed.

    Anyway, this makes me think the builder has done it right, assuming there is indeed waterproofing below the screed, a puddle flange, and correct sealing around the flange and waste pipe.

    You can see from Pulses diagram that if you simply combined both the top and bottom waterproofing in one job then the screed would have no way to drain.

    If I was examining that job I would also be looking closely at whether the bond breaking has been done correctly around the edges. That is where I found the waterproofer doing our job to be cutting corners and I think it would be critical in your older timber home.

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    Quote Originally Posted by RenoJoe View Post
    JohnC i did my best at snapping photos during the works.
    I just crawled under the house and got these pics. all is see is a screw on waste connection to shower grates.
    That's all I see - no puddle flanges, they should be between the waste and the shower grates?
    Under my ensuite floor, the puddle flanges are connected directly to the waste pipe below, the underside of the grates (shower and general area wastes) are not able to be seen. It also appears that a long section of the YT floor has been cut out for the linear drain which should be quite unnecessary?

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    Quote Originally Posted by ATMNut View Post
    It also appears that a long section of the YT floor has been cut out for the linear drain which should be quite unnecessary?
    Not saying it is the right way to do it but obvious from the photo from the original post that it’s the way that the drain has been designed to be fitted with the lip around the outside.
    Would have expected another level of flooring underneath the cutout so a puddle flange could be fitted and the waterproofing continued under the grate.

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