Help!: bonding v plaster

[callejasmin]

High there can some one please give me an answer to the following question as i have had people say yes and no to both!!

Q...Can you tile directly onto bonding or should one plaster walls first?

I appreciate that you shouldn't tile onto the skimmed surface..

Any definate answers please

Kind regards Callejasmin...................

[Dave]

NO you cannot tile onto Bonding/base coats.....not stable enough to tile directly to.

Why do you say you cannot tile onto skimmed surface..?

[callejasmin]

Thanks for your definative answer i was told that the thin skimmed finnish was to weak to hold tiles??

Thanks again

[doug boardley]

as a time served plasterer, categorically saying, DON'T tile onto bonding, tile onto skim ok, but be careful you don't overload the skimmed wall (weight wise)

[Dave]

You can tile onto skim but as doug says it has a weight limit and just depends upon the tile bieng used...

The weight limit is 20kg per sqr mtr..

[mikethetile]

you will need to leave new plaster dryout for 4 weeks before tiling

[whitebeam]

Thats why they use dry linning for fast track work, less time for drying out

[manclife]

Can you explain why shouldn't you tile onto bonding. I have to do a kitchen splashback and thats what the customer has used to level off the wall.

[Dave]

It is brittle and not stable enough to tile too..highly absorbant as well...

go to any manufactures site and it will state no tiling to base coats.

[mozzy]

correct me if i'am wrong, but i think if you use a cement based adhesive on plaster a chemical reaction occurs, so its best if you prime the wall first using mapei primer g this will enable the adhesive to bond with the plaster. plaster can only hold 20 kg per m2 mind.

[wall2floortilin]

you shoulnt go on tgo bonding as its the forming for gypsum to get a grip of when putting tile adhesive on to such substates the tensile strength is reduced, ie muti fix by granfix is nominal at 50nm, keraquick 100nm pod flex130nm"application to gypsum bonding products is minus 75%. this is a strict no no. tensile grip on to gypsum is negated by the substrate beneith it! 30kg onto dierct plaster board, 25 kg to skim on plaster board, anything less cannot be accepted. these figures are per square metre, please dont do what ithink you are or have been doing, we found this info out years ago and passed it on. cement render yes but not bonding. happy tiling

[Dave]

correct me if i'am wrong, but i think if you use a cement based adhesive on plaster a chemical reaction occurs, so its best if you prime the wall first using mapei primer g this will enable the adhesive to bond with the plaster. plaster can only hold 20 kg per m2 mind.

Ettringnite occurs when portland cement mixes with gypsum.....but tiling to base coats is another matter... same reaction but not stable enough to tile even without the reaction.