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Fixing heavy tiles to bare plaster bathroom wall

Hi, I have just started re-tiling my bathroom with some heavy(ish) ceramic tiles. I started at the top over the bath, and to begin with it was going great. But when I was about 3 rows down, I gently tapped a tile into place with a bit of wood and the one above it just fell off! Luckily I caught it, but what if this happens after the job is finished - it could seriously injure anyone sitting in the bath. Taking no chances, I stripped the remaining tiles off again and most fell off quite easily. I was fixing them onto a bare plaster wall which I thought was okay - now I'm not so sure. So, my question is: do I need to prepare the bare plaster wall before tiling, and what should I do to ensure they don't fall off once fixed in place? Thanks in advance for any advice!

Hi All,

Thanks for the advice - really appreciate it. Just to clarify, I don't have a problem with the plaster surface failing; it was tiled on before and despite being plasterboard it is very stable. The tiles I am hanging are Ceramic 250mm x 330mm and 8mm thick, so they are largish but not unusually so. I was using Mapei Ultimate Supergrab with a proper metal toothed spreader. The problem was that the adhesive just didn't seem to bond with the wall. The tiles came away very easily after being up for 3 days and there was barely a trace of adhesive on the wall (there were damp patches on the plaster where the tiles had been, so the wall had absorbed some of the moisture from the adhesive). However, the adhesive was stuck like concrete to the tiles! So, it's not the weight of the tiles that are the problem, or the place where I am starting, but the fact that they are not bonding to the wall for some reason. I have tiled several times before and always achieved very good results...and before one of the tiles unexpectedly fell off, the bathroom was looking awesome too! At the end of the day, safety is my main concern, so it sounds like I need to ditch the ready-mix adhesive and get some mix-it-yourself stuff to get the strongest bond? Thanks again.

9 Answers from MyBuilder Tilers

Best Answer

If you employed a professional tile he would have told you :
The maximum weight of tiling which can be supported by a dry, well-adhered plaster background is 20kg/m². This is equivalent to ceramic tiles with a maximum thickness of 8mm plus tile adhesive or natural stone tiles with a maximum thickness of 7mm plus tile adhesive.
I walk away from many jobs such as yours, Tile shops sell tiles with no advice on suitable wall makeup to safety take the tile.
You will need to overboard all your walls with a backboard such as 'hardie board' glued and screwed. This will allow you to go up to about 100kg m2.
You will also need to use the correct adhesive for the tile size and weight, not tubed adhesive!


Answered 29th Jul 2015

Hi Si, Sorry to hear about your difficulty but hopefully I may be able to shed some light on it for you. There could be several reasons for the problem of which I will outline some and you may realise what the issue is.
Firstly, the area to be tiled should be primed with a suitable acrylic based primer (not pva). This stops the moisture being sucked out of the adhesive too quickly and allows the tile to bond to the substrate.
Did you use a suitable trowel to spread the adhesive on the wall? You need to make sure that the tile has as close to 100% coverage of adhesive as you can get.
Was the adhesive left on the wall for too long before you placed the tiles?
Often, the adhesive will "skin over" if exposed to the air for too long before the tile is placed, this means the adhesive looses its suction so the tile does not stick properly.
Are you using the correct adhesive? For large format ceramic and all porcelain tiles you should be using a powder adhesive that you mix yourself rather than an adhesive you get in a tub which is ready mixed.
This is just for starters, if you have anything else to mention then do message back and I will gladly advise.

Best of luck
Inspired Ceramics


Answered 29th Jul 2015

Is it new plaster? If so you will need to paint the wall with pva glue.Tip some ova into a bucket and thin it down a little with water so you have a creamyish texture then paint onto the area you wish to tile and allow to dry.It should be dry enough to start tiling after half hour so.Start tiling fro the bottom and work up.tRue ova seals the plaster and will give you a surface for the adhesive to adhere to..Hope this helps


Answered 29th Jul 2015

Start at the bottom and work up. The tiles will support the ones above until the adhesive dries. If they are very heavy you will only be able to take them 3 or 4 courses in a day. Best of luck Mick


Answered 29th Jul 2015

hi you never start at the top bare plaster is ok to tile on you have to prime the walls then work out your tileing you will all ways end up with a cut or start with a cut kind regards ron


Answered 29th Jul 2015

Make sure you use a flexible mix it yourself adhesive. Rapid is better if you have confidence to set within an hr


Answered 16th Feb 2017

From reading this it seems you are tiling from the top downwards..... you should be starting from the bath and working up. you shouldn't need to prep wall but a bit of bonding cant do any harm.

What adhesive are you using?


Answered 29th Jul 2015

You should be using stanard setting powder adhesive , mapei p9 just the job


Answered 24th Jan 2017

You have been given a lot of answers but only one is right
Seal wall with acrylic primer dilute as recommended by manufacturers
Make sure the weight of the tiles doesn’t not weight anymore than 14kg per square metre so when you apply adhesive it’s keeps BSI regulation Which is 20kg weight limit or it will fail
If tile weight is higher then use Wedi board with Dow’s to fix on to surface using adhesive to fix with leave to dry and already to tile
That’s the correct way no other


Answered 16th Jul 2020

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