Tiles not adhering to wall.

ian bateman · 19 Aug 2015

I am currently tiling a bathroom wall. It has had a few holes and been filled with gap filler. I have tiled a small area and the tiles are not adhering to the wall very well and can be removed with a little force. The areas which have been filled are dusty and have not had a PVC wash applied. The adhesive is a Wickes tile adhesive product.

Can anyone assist me....or have any tips to allow better adhesion? Should I wash the plaster with a PVC wash...will this improve adhesion? Should I purchase a better quality adhesive.

All advice welcome. Thanks

Crystalclear · 19 Aug 2015

Without a doubt, a light skin of dust will easily create a skin between the adhesive and the wall.

Similar situation to when you you place cellotape on the carpet, and pull it off, and then when you try to stick it back on, it doesn't have the same strength? Tile adhesive is not liquid, so it can't pass through the dust on the walls, like paint would, so it sits ontop of the dust.

Remove all dust from the walls, and PVA is more waterproofer than a key for your tiles to lock into, in this case.

It depends on what tiles your using and if the adhesive is ideal for this use.
How far are you from you local Screwfix? These people are mega helpful, and I'd recommend a visit, and a quick chat as to which is suitable adhesive, basically, take a tile with you, and see what they can offer.

ian bateman · 19 Aug 2015

Thanks for that....I have been advised to consider BAL Primer and BAL Tile Adhesive......It is a good job that I tested a small area first!

Crystalclear · 19 Aug 2015

Newboy · 19 Aug 2015

Do not prepare any plaster for tiling using standard PVA - if needed then use a primer recommended by the adhesive manufacturer.

freddiemercurystwin · 20 Aug 2015

BAL products are good.

joe-90 · 22 Aug 2015

There's nothing wrong with the Wickes stuff. I used some a couple of weeks ago and it's good stuff. It takes weeks to reach full strength, stop messing around pulling them off the wall.

oggy02 · 1 Dec 2015

Hi
Just after a bit of advise, and would be grateful of any help. I have just PVA`d my kitchen ready for tiling. While checking up on this site, I see a lot of people do not recommend PVA. Will I be ok to apply a coat of the BAL primer over the top of the PVA.
Thanks

joe-90 · 1 Dec 2015

Nothing wrong with using PVA. We all used it for decades.

oggy02 · 3 Dec 2015

Thanks Joe, il have go this weekend.

London Mike 49 · 3 Dec 2015

This article may give you a better insight as to why you should not PVA prior to tiling;

2005.

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Mudster
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A while ago I wrote a post for another forum which explained the reasons behind not using PVA as a tiling primer, it is posted below for your information, I've been asked to copy it to various other forums and thought it might be useful here also. I hope it is of some help.

Oh and if you do require a primer then use one suitable for the adhesive you are using, such as BAL APD or Ardion 51.

I'm a professional tiling contractor, I now mainly specialise in natural products but over the years I've stuck up (or down) every type of tile there is.

I have to give guarantees for my work (many of these projects are commercial such as sports centre showers and changing rooms). For me to be able to give guarantees I need to follow strictly the specification of the adhesive manufacturers.

Ardex, BAL and Nicobond are the three suppliers I use most. Their products are similar in many respects, sometimes one will make products the other don't, and I also find some of there products more useful in different applications. All three of them have one thing in common, they all specifiy that under no circumstances may PVA be used before using any of their adhesives. If you do all guarantees are void.

OK why then? Well I asked this question to Ardex when I once had problem, I'd tiled a bathroom that had been constructed in 25mm Marine ply. Thinking he was doing the right thing, the builder got his guys to seal the ply with unibond PVA...I wasn't aware of this.

I tiled it and 6 months later every single tile fell off the ply, the adhesive solidly stuck to the tile but came clean a whistle off the ply.

We had Ardex Technical down to the site to compile a report, the basis of which was it's the PVA that causes the problem.

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, 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 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.

Ok so whats the difference between this and Ardex or BAL primer, well basically the tile manufacturers 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.

I hope this clears up any misunderstandings.

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oggy02 · 5 Dec 2015

Thanks London Mike
Looks like I may have to have a rethink, thanks for the info

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Tiles not adhering to wall.

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