tilling over hardwall in bathroom

[6spidermonkeys]

to all
can anyone tell me if its ok to tile over hardwall plaster which is going to be wher the new shower will be .the area is about 2.5 high and 600 wide .should i just hack it off and sand and cement it. or am i just being paranoid. cheers

 

[Gazzer]

Hi 6spidermonkeys and welcome to tilersforums.com

 

[6spidermonkeys]

cheers mate .thought i try this forum lark out .if you dont ask you don find out

 

[Andy Allen]

welcome to the forum, tiles can not be applied to any thistle undercoat plasters, except thistle dri-coat, so best to hack it off or scim over with a finish plaster...

 

[White Room]

If you hack it off why not dot and dab plasterboard....

 

[6spidermonkeys]

me thinks me be hacking it off and cement render.worth the piece of mind cheers al

 

[kilty55]

as above cant you dot and dab it ,tile quicker than a render

 

[6spidermonkeys]

can do whats the difference with hardwall and plasterboard apart from the paper on plasterboard there both pretty soft cheers alan

 

[6spidermonkeys]

can do whats the difference with hardwall and plasterboard apart from the paper on plasterboard there both pretty soft cheers alan
i think i know the answer to this would it make a difference if i pva the hardwall before tilling

 

[Bubblecraft]

Hi & welcome. PVA is a swear word about here. Unfortunately it is a big no no. As stated above, best bet is to dot & dab or coat with a finishing plaster

 

[6spidermonkeys]

sorry if i appear a bit naive but whats the problem with pva cheers alan

 

[Bubblecraft]

When you treat a surface with PVA it partly soaks in and parlty sits on the surface of the substrate much in the same way as wallpaper paste.

If PVA gets wet it becomes slightly live again, it doesn't completely return to it's liquid state but it becomes sticky.

When you spread tile adhesive onto the wall or floor, the water in the adhesive makes the PVA live and stops the adhesive from penetrating the substrate and providing a mechanical grip. Basically your tiles, grout and adhesive are being held to the wall or floor by a thin layer of PVA.

Most tile adhesive works by crystalising when it sets (some are slightly different such as epoxy based ones) but generally they all work the same way. Once the adhesive starts to set, crystals from and expand into any imperfections in the substrate surface (at a microscopic level) to create a grip. PVA stops this process by creating a barrier between the substrate and the tile adhesive.

Dedicated primers soak right in to the substrate and stop the sponge like "draw "effect but they don't coat the surface in any way, they are an impregnator as opposed to a barrier.

Hope that clears things up

 

[6spidermonkeys]

thanks mate

 

[6spidermonkeys]

can anyone recommend a suitable primer for the rest of the wall regards alan

 

[Bubblecraft]

What is the substrate made of or do you mean the new dot & dab wall?

 

[6spidermonkeys]

the rest of the wall is a combination of finish plaster and sand and cement ,plus the area where the shower is to be fitted is wbp ply cheers alan

 

[Bubblecraft]

Bal SBR mate. What size of tile are you using?

 

[Bubblecraft]

When you say "Sand & cement" is this an area that was recently done or is this an old scratch coat from under blown plaster?

 

[6spidermonkeys]

400 x 250 x 7mm ceramic cheers alan

 

[Bubblecraft]

If your sand/cement area is a smooth finish, you can use the SBR. If its a rough scratch coat or a bonding coat, this will need a skim or re-sheeted before applying an SBR coat.

 

[6spidermonkeys]

cheer for the info mate .will try and hack off hardwall at the weekend .should have trusted my instinct in the first place and used sand/cement .nevermind its all a learning curve.cheers mate.ps cant use dot and dab only have 10mm from wall to existing render line

 

[6spidermonkeys]

my mate has about four litres of everbuild sbr bonding . is this any good its going free
[h=1][/h]

 

[Bubblecraft]

Can't speak for Everbuilds own brand. I'd only use Bal SBR. May want to ask around. If you have only got 10mm, I'd use a bonding to bring it out & use a finishing plaster. Other option would be to use 10mm hardi-backer & bed onto tile adhesive (cement based). Guidelines below:

8. 1. Installation on brick walls
8.1.1 Preparing the substrate
Ensure wall is sound, clean and ready to receive HardieBacker®
250 cement board. At minimum, the rear of HardieBacker® 250
cement board and the masonry wall must be wiped down to
remove all dust.
8.1.2. Fixing sheets with tile adhesive, step 1
Bond HardieBacker® 250 cement board to the masonry walling
using tile adhesive. Apply tile adhesive to masonry walls using a
6mm notched trowel. The tile adhesive must fully support HardieBacker
® 250 cement board and the HardieBacker® 250 cement
board is firmly pressed into the tile adhesive.
8.1.3 Fixing sheets with masonry anchors, step 2
Use 9 pcs (3 rows of 3) ø 6mm x 50 mm masonry anchors with
self embedding head. The masonry anchors are immediately
fixed through the board into the masonry walls holding the
sheeting in place. Do not overdrive head of anchor, it must be
flush with face of HardieBacker® 250 cement board.

Note: Do not dot and dab tile adhesive!

 

[ASandOW]

Why can't you tile over gypsum products?

 

[Dongrand]

Why cant he just leave the hardwall up?