Tile weight limits on plaster - TilersForums.com

[Colour Republic]

Ok so we know tile weight limits on plaster is 20kg per sqm... or is it????

I've had a 'conversation' with someone about weight limits on plaster which made me look up data sheets to back me up. What i've found has left me unsure.

The formula i've worked to is

Tile + Adhesive should be = or less than 20kg sqm.

But on checking British Gypsum's website (let's be truthful, most of the the plaster is from them) I came across the following

Tiling:
Tiles up to 20kg/m2 can be applied to directly to Thistle Multi-Finish, except where the system includes a bonding agent. As the total weight limit of tiles and plaster applied over a bonding agent is limited to 20kg/m2, consideration should be given to tiling directly over to the background. If plastering to provide a background for tiles, avoid polishing the surface. Polished plaster surfaces should be roughened and a suitable primer used.

So lets take a few snipets...

Tiling:
Tiles up to 20kg/m2 can be applied to directly to Thistle Multi-Finish, except where the system includes a bonding agent.

I read this as... If the plaster is applied over a bonding agent, then the total weight limit of 20kg/m2 is to include the weight of plaster.

So the formula would be modified to:

Tile + Adhesive + Plaster should be = or less than 20kg sqm.

Now looking at the data sheets, it says the dry set weight of plaster @ 2mm is 3.4kg/m2, that takes the weight limits of Tile + Addy down to 16.6kg/m2. I know all situations on refurbs are different and these are only guidelines but still the plaster weight adds up to what we would normally use on addy right?

so if the above quote is right then multi-finish without the use of a bonding agent is still

Tile + Adhesive should be = or less than 20kg sqm.

But if the plaster is applied with bonding agent, then it should be

Tile + Adhesive + Plaster should be = or less than 20kg sqm.


The next part of the quote could be interpreted as one of two things:

Tiling:
...consideration should be given to tiling directly over to the background. ...

either, consideration should be given to tiling on to the background plaster, OR not doing any plastering at all and tiling on to the substrate to start with.

We know background plaster shouldn't be plastered on to (execpt for one), Gyproc say this in another data sheet

Tiles should not be applied directly to Thistle undercoats, with the exception of Thistle Dri-Coat

Gyproc Dri-coat is a cement based undercoat, which explains why it would exclude it from the above statement.

Sooooooo... Discuss

 

[White Room]

Yes, tile weight should be less than 20kg m2 because of the powdered adhesive weight with larger tiles but smaller tiles weight could be increased.

 

[Colour Republic]

Yes, tile weight should be less than 20kg m2 because of the powdered adhesive weight with larger tiles but smaller tiles weight could be increased.

Sorry WB you may have missed my point, from the data sheets it states that the weight of plaster (if a bonding agent is used) should be included in the weight limit of 20kg/m2

 

[Dan]

A brilliant thread. This will teach a lot of the noobs. Nice post CR. I've added to your reputation.

 

[Dan]

It's already ranking too.

 

[Colour Republic]

It's already ranking too.

You're such a geek :rofl:


(ok, I know that's pot, kettle, black, but I don't care)

 

[DHTiling]

Yep a good post and I've upped your reputation as well..

Have you checked any other suppliers for info on this weight ratio..?

 

[White Room]

Sorry WB you may have missed my point, from the data sheets it states that the weight of plaster (if a bonding agent is used) should be included in the weight limit of 20kg/m2

I'm with you now Rob, I new that pva was only up to 20kg and plaster at 2-3mm was a minimal weight but a float and set with bonding with pva as a sealer could reduce the weight some what.

Good point there mate.

 

[Alan.P]

Mmmmm, cat amongst the pigeons, can I suggest to a mod / admin that this is moved out of public view before a stampede, at least while we talk about it.

 

[DHTiling]

Good idea Alan.. moved to arms for now..