My first Project > Shower and Waterproof kit

Bucki

hello

just got my first house and thought I challenge myself by doing a complete makeover of the on suite.

stripped down tiles and all that and fitting a corner shower in. Now, looking into this MAPEI shower waterproof kit:

does it really work to apply it on non-water resistance plasterboards?? 

If so, do i need to prime the board before applying this? Is it worth it?

Further more, i will tile the walls to, so i still need to use acrylic primer before tiling?


 

justwhat

had to look to see what's in the kit out of curiosity. (i would not use it)..see link below

https://victoriaplum.com/blog/posts/how-to-prepare-walls-for-tiling

FreeBear

Bucki said: Further more, i will tile the walls to, so i still need to use acrylic primer before tiling?

Yes, you should use an acrylic primer before tiling. In the grand scheme of things, it is not a huge expense, and it will ensure the tiles remain on the wall. If you are using a large format tile, it is well worth using one of the tile leveling kits.

If you are stripping the walls back to brick (or stud), it would pay to use cement board, especially in any shower/bath area.

Bucki

justwhat said:

had to look to see what's in the kit out of curiosity. (i would not use it)..see link below

https://victoriaplum.com/blog/posts/how-to-prepare-walls-for-tiling

Hi, 

in regards to PVA, they say NOT to use PVA before tiling. However, I am referring to the Mapei Shower Waterproof if that can go on top of normal plasterboard as I have not used water resistance one.

Bucki

FreeBear said:

Bucki said: Further more, i will tile the walls to, so i still need to use acrylic primer before tiling?

Yes, you should use an acrylic primer before tiling. In the grand scheme of things, it is not a huge expense, and it will ensure the tiles remain on the wall. If you are using a large format tile, it is well worth using one of the tile leveling kits.

If you are stripping the walls back to brick (or stud), it would pay to use cement board, especially in any shower/bath area.

Indeed cement adhosive was used to attach plasterboard to the bricks. 

Now, i was naive not to use water resistance plasteboards and have used normal standard one instead. My idea was to apply Mapei shower waterproof on top of the plasterboard but thinking that it may cause damage due to plasteboard soaks any liquid applied and tbis wont do any benefit and be waste of money and cause more problems.

so, in sense:

- apply waterproof over plasterboard
- let it dry
- apply acrylic primer on top
- then tile adhesve (dont think is water resistance) and add tiles.

tiles are 600 by 300 large.

FreeBear

If all you are doing is trying to "waterproof" the plasterboard, then SBR might be a cheaper solution. Prime the PB with a coat of SBR, and then trowel a thin layer of thinset (mix some SBR in) over the top. Embed some render mesh into the thinset and give it a light trowel over.

With 300x600 tiles, definitely use a leveling kit. Well worth the extra expense.

Bucki

My main concern is:

Whether to apply Mapei Shower Whaterproof on top of plasterboards or not? I am worried that it will just soak the substance in and do nothing because plasterboardw are not water resistance

FreeBear

I would be more concerned about the load capacity of the plasterboard. A skimmed plaster finish will take 20Kg of tiles/adhesive/grout per square metre. Bare plasterboard is 32Kg per sq m, and cement board will take 50Kg+. 600x300 tiles are very heavy, and even on bare PB, you are getting close to the limit once adhesive & grout has been included.

Bucki

FreeBear said:

I would be more concerned about the load capacity of the plasterboard. A skimmed plaster finish will take 20Kg of tiles/adhesive/grout per square metre. Bare plasterboard is 32Kg per sq m, and cement board will take 50Kg+. 600x300 tiles are very heavy, and even on bare PB, you are getting close to the limit once adhesive & grout has been included.

Good shout actually.
I dont think i will skim the plasterboard and go straight to acrylic primer (or diluted PVA 3:1) and adhesive and tile.

even if I skin, it be a very thin coat.
wall is not 99% straight but should be OK adding more adhisive.

 

Would that not work?

FreeBear

Do not use PVA as a primer. Acrylic primers don't cost a huge amount, and you'll only need a relatively small quantity.

If you are sticking with plasterboard, do not skim with Multifinish (or similar), just tile straight on to the PB.

justwhat

i have always used a weak solution of pva. Many say do not use. The only possible drawback would be putting the pva on that  thick it would effect effective adhesion of the final finish.

Some of these primers were never used in yester year.