Tile to weight ratio

[whitebeam]

There's been a fair bit of debate on this one, So I phoned British Gypsum and spoke to there tech line, Is as follows;

They reccomend that you don't tile directly to standard plasterboard, Should be skimmed first. 20kg

Moisture resistant board can be tiled onto directly at 32kg

Float and set is 20kg

I'm sure this will cause some discussion, Tiling direct onto plasterboard was the one that surprised me

Rang BG again about the standard board and had a different answer, Would be ok in a dry or small area to tile onto. Thats from two different techi's Just trying to get the facts right

[grumpygrouter]

Thanks for that Whitebeam. Must say I am confused now. I was taught that you can tile directly to plasterboard (no skim) without the need for primer and that the max weight was 32kg. In a previous post you corrected me on the weight issue which I accept. Only BAL say you have to prime plasterboard as far as I am aware. Why do BG say you can't tile straight to normal plasterboard, this is the first I have heard. Did they give a reason?

[Droopy]

As long as it is a min of 12.5mm thick, I thought you could tile direct to any plasterboard. Yes, moisture resistant is prefered, and required for bathrooms in new builds (as far as I am aware), but I didnit think it was a must.

As for priming, you do not have to prime when using our dispersion adhesives, but you MUST prime when using any Cement based addy, not just BAL's.

[grumpygrouter]

As long as it is a min of 12.5mm thick, I thought you could tile direct to any plasterboard. Yes, moisture resistant is prefered, and required for bathrooms in new builds (as far as I am aware), but I didnit think it was a must.

As for priming, you do not have to prime when using our dispersion adhesives, but you MUST prime when using any Cement based addy, not just BAL's.

The SystemArdex manual doesn't specify any primer for plasterboard with their cement adhesives!
Neither does the Weber Manual as far as I can see........

[Droopy]

The SystemArdex manual doesn't specify any primer for plasterboard with their cement adhesives!
Neither does the Weber Manual as far as I can see........

Seeing as the problem of Ettringite is caused by a reaction between gysum and cement, I don't see how one company's cement can cause it and another company's not.

If I were you, and using one of these company's cement based products onto plasterboard without priming, I'd phone their Tech line and ask about the possibility of Ettrignite failure.

[grumpygrouter]

I know where you are coming from James and I agree with what you are saying, but as far as I know it is only BAL that stipulate you MUST prime plasterboard. puzzling really. Not really an issue for me because I am only using BAL for walls anyway so they get primed but it will still now be an interesting debate I think.

[Droopy]

I know where you are coming from James and I agree with what you are saying, but as far as I know it is only BAL that stipulate you MUST prime plasterboard. puzzeling really. Not really an issue for me because I am only using BAL for walls anyway so they get primed but it will still now be an interesting debate I think.

These other companies must put a helluva lot of faith into that layer of paper then.
I always primed plasterboard before using cement based adhesives on them.
So I'm not talking as a BAL support technician on this issue, but as an experienced Tile Fixer.

I wouldn't risk a failure for the sake of some primer.

[brian c]

very interesting thread this one lads.

[Droopy]

very interesting thread this one lads.

It would be nice to hear from someone who knows the reasons why these companies say not to prime.

I, again as a Fixer, would love to hear them.

[whitebeam]

The issue that comes mind is most new housing is dry lined and I've tiled on new board with a site agent standing there watching me, Years ago on site we had skim the walls before tiling, Personally I will continue tiling on plasterboard when required but may use MRBoard if doing a full dry linning in moisture areas

[JonathanC]

British Gypsum publish 'The White Book' which gives detailed guidance on application of tiles to both plaster and plsterboard backgrounds.

It states

'Tiles can be applied to drylined walls or the surface of lightweight partition systems to dado level or above. Tiling can be carried out in any type of building either in dry areas or in areas subject to intermittent moisture conditions. Typical applications include domestic shower areas, toilets, bathrooms and kitchens. Tiles up to 12.5mm thick with a maximum weight of 32kg/m

2 can be accommodated (20kg/m2 for a plastered surface). The tiles are fixed using a suitable thin-bed adhesive applied to a nominal 3mm thickness.
The use of Gyproc moisture resistant grade boards is recommended for
intermittent moisture applications, including splashbacks. Alternatively, for
splashbacks, boards can be coated with two coats of Gyproc Drywall Sealer to prepare for tiling. Cut edges of plasterboards must be appropriately sealed / caulked at abutments.'

Full details are on http://www.british-gypsum.com/