applying heavy travertine tiles to plaster and plasterboard

[trullock]

Hi,
I've read a lot of posts on here quoting the fixing weights of 32Kg/m^2 for plasterboard and 20Kg/m^2 for plaster detailed further here: http://www.baladhsives.co.uk/newpdfs/literature/sitework_guidance.pdf.
The bathroom I'm tiling has two external and two internal walls (external walls don't have cavities).
The two internal walls are plastered plasterboard, and the two external walls are plastered brickwork.
The shower and bath will sit in the corner of an internal and external wall.
I've worked out that the travertine tiles i want to apply to all walls are approx 28Kg/m^2.
Assuming the above figures for plaster/plasterboard are correct, my plan was:
Remove all the plaster from the external walls and assuming they are sufficiently flat, tile straight onto them (if the wall is not flat, give it a quick skim with some quickset render)
For the inside walls, i was going to replace the plasterboard with new plasterboard, and seeing as with tile adhesive i'll probably be at the 32Kg/m^2 limit, i was considering affixing some galvanised expanded steel mesh over the plasterboard (making sure its firmly affixed to the wall studs) to give it a touch more strength.

What do people think? Any recommendations? I know of products like aquapanel/martox/hardibacker but its gonna cost me a fortune to do all the walls in this Do i REALLY need it?

Thanks for any advice

 

[White Room]

Why don't dry line the external walls, it will give you a better surface rather than fix to brick wall with a bit of adhesive to level them out

 

[doug boardley]

what plaster is the base plaster on your external brickwork? if it's gypsum based it's a definite no no to tile onto, but if it's sand and cement, that will be fine to tile on once the skim coat is removed. As for the internal walls have you considered the total weight that the adhesive, grout and tiles will amount to?, better to use 12.5 mm hardiebacker on the internal walls imo

 

[trullock]

what plaster is the base plaster on your external brickwork?

Not sure, its pink, with a very smooth surface. It clearly wasnt primed as the existing tile adhesive and paint have come straight off as though they were never there!

 

[White Room]

Thats the finish, what is the backing underneath the finish

 

[trullock]

Thats the finish, what is the backing underneath the finish

Underneath it looks like another thin layer of finish, and underneath that a thicker layer of (excuse my complete lack of knowledge of all things plaster related) sandy/cementy stuff, looks and feels like mortar.

 

[White Room]

If the mortor is strong scrape the finish off or put a wall paper steamer on the plaster, keep there for a while and it will blow the finish.

If the undercoat is render and it's not crumbly use some primer on the walls to alleviate any dust

 

[trullock]

If the mortor is strong scrape the finish off or put a wall paper steamer on the plaster, keep there for a while and it will blow the finish.

If the undercoat is render and it's not crumbly use some primer on the walls to alleviate any dust

cool, and that will be strong enough to tile onto with the heavy travertine ive got?

 

[White Room]

If the render is good it will take about 40kg m2

 

[doug boardley]

.... if it's sand/cement render, yes

 

[westerhopetiles]

use hardybaker its not that much money about £10 pound a board you get a great fix and its fully waterproof

 

[trullock]

Hi, Thanks for all your advice.

I've gone for Hardibacker 500 on the internal walls. Am I right in thinking I can tile directly onto them with a white spf adhesive, no need to prime?

I'm debating what to do with the external brick walls. If I Hardie those too, i understand i need to plug and screw them to the wall and put adhesive behind them to stop the screws/uneven wall cracking the board. Is this correct? If so, what sort of adhesive should i use to stick the hardibacker to the brickwork?

Its going to cost at least another £100 to board over the bricks plus the adhesive i need What should i expect to pay to have 8m^2 of wall professionally rendered with cement/sand?

Cheers

 

[westerhopetiles]

spf will stick no problem but its rapid i would go for set plus it will do the same job just have the price and hardy all the way

 

[DHTiling]

Leo!!.. you need to read your spec sheet on Hardi backer boards.. they are not fully waterproof... just water resistant.. as in they do not break down in constant contact with wetting.

 

[paulyoung666]

that will be weber setplus then will it