Tiling with brick slips on plaster

[thesop]

Hi, I have bought some brick slips and am a bit stuck on how to fix them on my newly (8 weeks old) plastered walls. The supplier has said I can put them directly on the plaster if it's sound, which it is, however the bag of multi finish that was used says maximum tile weight of 20kg/m2 and I make the brick slips to be around 30kg/m2. I'm worried that with this and then the mortar the weight will be too much. Any suggestions on what I should do. It is a brick wall with old plaster which has been skimmed over. Hope someone can assist. Alex

[marcusjkw]

score the walls 3 or 4mm through the skim into the old plaster and the mortar will glue it all together

[Colour Republic]

I'm sorry I wouldn't score the plaster at all. Especially seeing as you say that is has been recently skimmed over old plaster. If you score 3-4mm you will effectively be going back to the old plaster and just cutting up the new skim and weakening it.

The correct answer is that really at that sort of weight you should be fixing cement backerboards to the wall, glued and screwed. However the 20kg per sqm is a guideline, in reality you can fix much more than this if the plaster and background is solid and also much less than this if not. Just because a wall feels smooth and solid doesn't always mean it is, sadly it's hard to advise you how to test the strength of the plaster as it is just one of those things that comes with experience and is often a judgement call made by the installer if he/she is happy to proceed.

So whilst there is a chance you could fix the slips without issue, it's not something I personally would want to advise without seeing it first hand and so the safest route is to install cement backerboards first. Many backerboards are rated in the 40-50kg range (if mechanically fixed too, i.e. screwed)

[wine~o]

SOP, is this plaster to the wall or on plasterboard ??

[thesop]

Wino, hi, it is plaster skim over old plaster over brick.

Colour republic, am I alright to do that straight over the old plaster?

Thanks in advance