Making the best out of bad job - TilersForums.com

[electricsheep]

Hello with an SOS! I'm a complete newbie to DIY and everything I've learnt so far I've learnt from the interwebs and I hope this forum will be my salvation for my tiling problem.

When I was cleaning the kitchen in the 10-year old flat we recently bought, two and a quarter tiles fell off the corner where the tiling extends onto a very tall pillar. We subsequently removed the four tiles below which were also loose. I've cleaned off the old adhesive on the loose tiles and the area where they were fixed to the best I can. I've attached a picture of this area.

My problem is that the top part of the area where I want to re-stick the tiles seem to be made of MDF (I think it’s MDF anyway - it looks like exactly like the material the backs of Ikea Billy bookcases are made of), while the bottom half seems to be made of real wood - plywood I think. I managed the clean off the plywood area reasonably well but the MDF area is still sticky to the touch.

All my extensive Googling tells me tiling onto MDF is a big no no, but I have no option but to work with the dual surface areas I have - the pillar goes up to an unusually high ceiling and I would not want to strip and re-do anything as we can't afford something like that. I've seen people recommend Aquaplane but this does not sound like a good option to me, as the rest of the surrounding tiling is okay and the width of the Aquaplane would make my repair job obvious.

I bought Unibond's Advanced All Purpose Tile on Walls waterproof adhesive and grout from B&Q - which to my dismay many tiling pros seem to scoff at. However I didn't know any better and as I don't have a car B&Q is my best option as it's within walking distance. The preparation instruction on the tub says to "Prime porous surfaces with 1 part UniBond PVA diluted with 5 parts water, and allow to dry. Seal timber with solvent-based primer."

WHAT SHOULD I DO?? I feel so clueless and frustrated because BOTH types of areas I have seem to be problematic, which is no doubt why the tiles fell off in the first place.

I presume the MDF is a porous surface, so should I trek to B&Q again for this Unibond PVA? I'm worried as I've read so many posts that say that PVA is a no-no with tiling adhesive. And it's only for a surface area of 2.25 tiles of 15x15cm. And as for the plywood area, do I just sand it and tile as normal, or should I use a wood primer first?

Please please advise, I'll be so grateful!

(and thank you to anyone who has had the patience to read this really long post)

 

[faithhealer]

good news, you've found the right forum, big welcome. You are right so far about MDF PVA etc so don't touch them. Where abouts in London are you, we have a few members who might be willing to give you some advice . Give our 'gaffer; dave a pm and he will know someone in your area. tilersforums.com | Tile Forums | Tiling Forum - View Profile: Dave

 

[Daz]

Mapei Keraquick is guaranteed for use on MDF provided the surface is stable, clean and primed with their Primer G product.

The plywood will need to also be primed with Primer G before tiling that with the Keraquick too.

As Faithy has advised, it is worth getting a pro to take a look as the ply may have become contaminated by the previous adhesive and therefore no longer be suitable to tile to :mad2:.

BTW, welcome to Tilersforums .

 

[suave]

:welcome:

 

[doug boardley]

why can't you replace the MDF and plywood with plasterbaord? If I'm looking at your picture properly it looks like a vertical pipe boxing.

 

[mikethetile]

Hi and welcome to tf

replacig with plasterboard is the best solution in this case, you could sand and seal the ply and mdf and then prime as already advised

but take the unibond products back to B&Q as they are not up to it and the job will likely fail

whatever you decide you will get first class no nonsense advice from here and we will talk you through the job

 

[scribbler]

Some adhesives work on uncontaminated mdf and also ply, but since you say it's "sticky" and looking at the size of the adjoining black tiles, I'd opt for carefully removing both mdf and ply (do you know if cables or pipes run behind it? It's worth considering) and replacing with plasterboard and if needed add extra noggins to reduce flexing. Tape over any joins.
If your tiles are porcelain, use a cementitious adhesive and make sure you use the correct primer so it doesn't react with the plaster.

Good luck electricsheep.

 

[electricsheep]

Hi Doug,

I could in theory replace the MDF and plywood with plasterboard, but I wouldn't be able to do it myself and it will be an expensive job. This is because we have an open plan living area and the ceiling is about 15 feet high (the flat is a conversion). The area with the tiles is on the central vertical column that supports a large ceiling beam, and also conceals pipework I believe.

Also, replacing the old material of this pillar would mean a repaint job for the whole thing, which at 15 feet high means scaffolding and what not. My stomach feels a bit ill just thinking of the time and cost involved, along with all the other DIY tasks we still have to tackle. All because 6 tiles have come loose!

So this is why I say I have to work with the situation I've got - which is slightly dodgy MDF and plywood.

 

[mikethetile]

you dont need to replace up to the ceiling, depending on the thick ness of the ply and mdf, if they are same thickness you can cur out 10mm below top of tiles , fit a noggin to carry the board and tile up on the plasterboard

is it possible to remove the mdf and measure the thickness of the ply

 

[aqua blue]

For what it's worth I would clean off mdf and sand with 120 grit. Apply 'MDF' primer.
The ply looks to be screwed to battens, if I'm right, I would take the four screws out and replace with brass. Sand off ply 120 grit again. Between the ply and mdf there looks to be a seam, I would use a plasterboard mesh strip saturated in a two part- (with hardener) epoxy glue, which I would also single coat the ply with.
The tiles I would clean up the best you can. A grinder would be handy to clean off old adhesive from the tile backs.


You will then need a white cement based flexible adhesive, non sanded grout and silicone. Strip the silicone off completely on said wall and recaulk.