To tank or not to tank

[Danetre]

I have to tile a walk in shower using limestone tiles which weigh in at 30+ kg/m3

Could I tile straight on to the concrete blockwork and would the blockwork need priming first?

If I use hardiebacker boards do I need to tank as I understand tanking reduces the weight the wall will take?

Any advice appreciated

 

[High Peak Tiling]

Hi there Danetre.

I would not tile straight onto Blockwork, I recommend :
Clean block work of snots dirt dust flakeyness & free of paint etc.
prime with SBR.
Dot & Dab tile backer board plumb & Flat, making sure all joints are boardglued together.
Tank whole board installation.
Then tile.

Hint: As you have created a water tight strong substrate, you still have a porous Tile (stone)
making sure the tiles & grout are sealed properly and Silicon'd.

 

[Dougs Third Go]

contrary to the myth, hardiebacker board isn't waterproof, it's water resistant and won't degrade when subject to water ingress, but moisture will pass through it.:smilewinkgrin:

 

[High Peak Tiling]

I have to tile a walk in shower using limestone tiles which weigh in at 30+ kg/m3

Could I tile straight on to the concrete blockwork and would the blockwork need priming first?

If I use hardiebacker boards do I need to tank as I understand tanking reduces the weight the wall will take?


Any advice appreciated

Answer to your Question,
Q: reducing the weight the wall will take... ?
A: no, it wouldn't affect the walls strength.

 

[Danetre]

Thanks Hi Peak

I rang Bal today regarding using WP1 but it will only carry 32kg/m2 and the tiles alone are around 35 kg. Surely someone else has had this problem as stone tiles are very common now.

Do you know the reason for not tiling direct to block, they are concrete and not cinder.

Any other ideas?

I accept the stone will have to be sealed.

 

[Danetre]

Sorry, I should have said reduce the weight the backer boards would take
Please see my response to your earlier post

 

[Danetre]

Hi Doug
I thought this but I rang Hardie today who say if its properly taped it doesn't need tanking, very confusing!
I thought I would come to the forum for some proper advice from experienced guys

 

[Dougs Third Go]

it is feasible to tile straight onto blockwork, priming not essential if they're concrete blocks..If you used a membrane tanking system as opposed to a paint on tanking system weight ratios should be okay.

 

[High Peak Tiling]

Thanks Hi Peak

I rang Bal today regarding using WP1 but it will only carry 32kg/m2 and the tiles alone are around 35 kg. Surely someone else has had this problem as stone tiles are very common now.

Do you know the reason for not tiling direct to block, they are concrete and not cinder.

Any other ideas?

I accept the stone will have to be sealed.

Hi Danetre, I was recommending what I would do, by all means listen to Doug. I prefer to create a substrate that's all.
Good luck.

 

[Danetre]

Thanks High Peak

I agree with you and that is what I am doing on 3 walls (1 is battened, 2 are stud) but I don't want to lose any more space on the 4th wall as it is already tight, hence the question.

Its the tanking that I cant sort because of the tile weight it has to carry unless you know of a system that will take that weight.

 

[Danetre]

Hi Doug

Are you talking about a membrane under the backerboard?

 

[Dougs Third Go]

Hi Doug
I thought this but I rang Hardie today who say if its properly taped it doesn't need tanking, very confusing!
I thought I would come to the forum for some proper advice from experienced guys

it all depends who you speak to in their tech dept, some say it's waterproof, others don't toe the party line and say it isn't.

 

[Danetre]

Hi Doug, thanks for reply, can you recommend a membrane system that will carry 35-37kgs/m2

 

[One Day]

I would clean and prime the blockwork, and fix kerdiboard using adhesive and fasteners.
(like these : http://buderussolaronline.com/wp-content/themes/responsive/images/kerdi_build_panels_accessories.jpg)

Tape joints and fastener heads and you're good to go.

Personally I would not want to hand that much weight on a membrane (I hate the stuff)

 

[cam_low]

jackoboard, marmox, wedi etc are all a system of boards I would use. I wouldn't dot and dab the boards I would prime and use a trowel to fix them, possible using fixings once the adhesive has set.