Tiling Bathroom floor advice

[steverino75]

Hi,

I am undertaking a DIY tile my bathroom floor and walls project and would like some advice please.

I have purchased the tiles, which are porcelain 30x60cm and 0.5cm thick.

The bathroom had lino on before and on removing there is a layer of 1cm mdf screwed down to 2cm floorboards with the joist spaced 30cm apart underneath. I understand that tiling direct to MDF is a no go and also when I walk on the floor it flexes in places. I did the water in a glass trick and it ripples when i move around.

So firstly I need to stiffen the floor. What would you recommend? Remove MDF and put down some WPB Ply 25mm? or something not so heavy on top of the MDF?

Can I then tile directly to the WPB? or if not what primer etc would you recommend?

In fact if you could recommend products that I would need from the floorboards up to adhesive for tiling the floor that would be great.

With regards to the walls I have had a plasterer skim them flat for tiling and it is completely dry. Can I Tile direct to the wall or if not please can you recommend a product. BAL SBR? and an adhesive that would be good for that type of wall?

I would be grateful for any help, before I start as I want to get it right.

Many thanks in advance

 

[John506]

I would remove the MDF, and screw the floorboards down were it flexes.

You then need to screw half inch marine ply to the floor, screw every 6 inches or so to make sure it is properly secure.

Use 3/4 inch screws or something so you don't go through the floorboards into any pipes.

Primer depends wether the manufacturer of your choses floor adhesive recommends it. Personally, I would prime it anyway for a better job.

You should be good to go when tiling straight onto the dry skim, done it loads of times and had no problems

 

[PrenticeBoyofDerry]

Surface preparation will depend on the adhesive you use, some are self priming and others recommend the primer to be used.
I tend to stick to the MI (manufacturers instructions) so if there is a problem I know I have done what was required and it's the product that has failed.

If using BAL cement-based powdered adhesives, apply 2 coats of neat BAL Prime APD or BAL Primer or 2 coats of BAL Bond SBR diluted 1:2 with water.

If using BAL ready-mixed adhesives, priming is not necessary UNLESS the plaster is very shiny and dusty. If so, brush surface with stiff bristle brush and prime with BAL Prime APD or BAL Primer diluted 1:1 with water or BAL Bond SBR diluted 1:4 with water.

Porcelain tiles have extremely low porosity. Ready-mixed adhesives rely on water loss through the joints, background substrate or tile to achieve full bonding. As the tiles have low porosity and joints are reduced due to the large tile size, ready mix products struggle to set. Instead, prime the plasterboard with neat BAL Prime APD or BAL Primer, and then use highly polymer-modified adhesive such as BAL Single Part Flexible or BAL Rapidset Flexible. These set via a chemical reaction.

info care of Bal

With large format tiles, I would go for rapid set
I seal porcelain tiles before grouting as they can stain.

 

[Karis]

For the floor, ultimate is to rip it all up & start again with WBP, 18-25mm depending on your floor construction. At the very least the MDF has to go & then overboard the floorboards with minimum 12mm WBP (you don't need marine ply) or a decent tile backer board. You must use powder adhesive but if the 40 minute pot life of Rapidset is too much for you, use Single Part Flexible.

If your tiling, refinishing in plaster was not a good idea as plaster has weight restrictions which will be a problem if you’re planning similar sized/weight tiles for the walls.

Priming will depend on your tile base & the size/weight of tiles which dictates the type of adhesive you need to use. BAL is good but expensive stuff & you should always follow the manufacturers instructions, BAL recomend priming/sealing the underside of ply overboard but do not recomend priming the top tile surface. Plaster/plasterboard must be acrylic primed when using powder based adhesive.