Tanking GTEC Aqua Board & Formed Screed Floor

[AndyH747]

Hi All,

I'm about to prepare a shower area in a new build for tiling. The floor of the shower area has been screeded with sand/cement mix on top of UFH. The screed has been formed to slope towards a screed drain. The walls of the shower are GTEC Aqua Board on studs. I want to tank the whole floor area of the shower and up the walls using BAL WP1 or similar.

A few questions I hope the experts can answer:

1. What do I need to to prepare the screeded floor with before tanking? The rest of the ground floor is liquid screeded and they supplied a sealer for this. Can I use this sealer on the screed and then tank on top?
2. What primer is required, if any, on the Aqua Boards? The boards come to floor level and meet the screed so I intend taping at this point with the BAL kit.
3. I was only going to tank half way up the walls of the shower as going to the ceiling seems a bit overkill. What are the recommendations?

Thanks in advance.

[diamondtiling]

If you have used aqua panels for the shower walls then you dont have to tank them, just tape the corners and joints or fill with silicone. You could use a tanking membrane on the floor, make sure you cut it into the drain.

Have you brought the UFH up to maximum temperature and then allowed to cool ? Very important that you do this.

[AndyH747]

Yes the UFH has been brought up to temperature and cooled. This is long build and the screed was laid over a year ago!

Although I can do as you suggest I want to tank it as well. It's belt and braces and I'd feel happier for the £60 it costs for a tanking kit. I just want to know the advised preparation of the walls for this.

[whitebeam]

It says it's water resistant not water proof

Lafarge Aqua Board - Plasterboard for use in wet or high humidity environments

[AndyH747]

Exactly why I want to tank it.

All I'm asking is what to use to prepare it as BAL seem to suggest using their flexible adhesive BEFORE priming and tanking. I'm wondering if anyone has carried this out without using the adhesive first. I would have thought the BAL primer would ahve been sufficient.

[whitebeam]

It also state it's a gypsum product..not heard of giving it a coat of flexi addy before tanking..

I would give Knauf a call just to check.

[AndyH747]

It's not made by Knauf it's made by Lafarge GTEC. Knauf's product is Aquapanel, Lafarge's product is Aqua Board. The guidance from Lafarge is that it only needs primed but they can't comment on how other manufacturers tanking products work. That's why I'm asking here to see if anyone has tanked onto either Knauf Aquapanel or Lafarge Aqua Board. The manufacturers have not been very helpful up to this point.

[whitebeam]

My error

[diamondtiling]

Andy are you sure you want advice from the forum? we are trying to help you as much as we can. What is it that you specifically need to know?

Aqua panels do not need to be tanked, you should do as I suggested in my first post.

[whitebeam]

I would prime and tank but I use Dural wp water membrane.

[jay]

i would prime and tank
all areas effected by shower 1.8 high to screen ,if no screen then go 1,5 away from shower rose
hope this helps

[AndyH747]

Andy are you sure you want advice from the forum? we are trying to help you as much as we can. What is it that you specifically need to know?

Aqua panels do not need to be tanked, you should do as I suggested in my first post.

Yes that's why I posted but it appears you were unable to advise. You are in a minority that doesn't think it needs tanked. As has been stated the Aqua Board is NOT waterproof, only water resistant.

The question of whether to tank or not is academic as that's what I'm doing. What I was asking was the preparation required on the Aqua Board before applying the tanking substrate.

I'll take the advice of the other posters and tank as recommended. Thanks to the other posters for answering my query.

[diamondtiling]

Yes that's why I posted but it appears you were unable to advise. You are in a minority that doesn't think it needs tanked. As has been stated the Aqua Board is NOT waterproof, only water resistant.

The question of whether to tank or not is academic as that's what I'm doing. What I was asking was the preparation required on the Aqua Board before applying the tanking substrate.

I'll take the advice of the other posters and tank as recommended. Thanks to the other posters for answering my query.

Just looked at the Lafarge aqua BOARD website and they are indeed different to aqua panels so you have my apologies, I should have checked earlier.

Just one question then, why would you choose to use a board in a wet area that clearly is insuperior to aqua panels? It cant be used on floors and it needs tanking? Seems like a complete waste of money and time.

Lafarge Aqua Board - Ask the Experts

[Dave]

Morning andy

The lafarge boards are great and can be tanked over no problem.

Prime the Walls with APD and leave to dry and then 2 coats of WP1, leaving to dry between coats and yes taping internal joints and wall to floor transitions.

Can i just ask , is this an anhydride screed ? If so , who's


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[Ajax123]

[QUOTE=whitebeam;515239]It says it's water resistant not water proof

The difference being ????

[AndyH747]

[QUOTE=Ajax123;515385]

It says it's water resistant not water proof

The difference being ????

I would have thought that's obvious.....


In answer to the question on screed, yes it's anhydrite screed. It was supplied by Flo-Screed. Their website is here:
Supaflo Floor Screeds

[Ajax123]

[QUOTE=AndyH747;515387]

I would have thought that's obvious.....

I disagree......It is far from obvious......I have had the debate many many times. As far as I can see the two are synonymous terms. In order to make something water resistant you waterproof it. For a material to be waterproof it must be water resistant.

I do know a little about flowing screeds......Supaflo is not anhydrite unless you are in Ireland??

No offence intended by the way

[Dave]

Water resistant is when a product will not break down in contact with water and water proof does not allow any water to enter it.. water resistant boards will wet up and soak in moisture but not fail.. as in fall apart like gypsum plaster boards can.. Waterproof boards will not allow water to soak in and through them.... the surface on Marmox type boards will become wet as the cement face wets but the core of the board will not allow the passage of water..

So yes water resistant is different to waterproof IMO...

[sam_b]

Morning andy

The lafarge boards are great and can be tanked over no problem.

Prime the Walls with APD and leave to dry and then 2 coats of WP1, leaving to dry between coats and yes taping internal joints and wall to floor transitions.

Can i just ask , is this an anhydride screed ? If so , who's


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Bit of an old post to resurrect but hey.... the tanking kit I was looking at (Megaproof Waterproof Tanking Kit) comes with SBR primer, is this fine to use as well, as opposed to the APD primer mentioned above....

Thanks,
Sam