Plasterboard for tiling. Straight or tapered edge?

[krismusic]

Hi guys. Got myself involved in another job that I don't know enough about! I am preparing a friends bathroom for tiling.
I am using a waterproof tile backer board for the shower area but for areas well away from water I am intending to use MR Plasterboard.
The joins will be supported and screwed to studwork.
Do I need to use taper edge Plasterboard and tape and fill the joins or could I just use square edge and tile straight over the joins?
Thanks for any advice.

 

[Richard C]

Square edge but tape & fill the joints with tile adhesive; avoid tile grout lines coinciding with board joints if you can. What type/size/weight are the tiles?

 

[krismusic]

Thanks Richard. Tiles yet to be chosen and put up not by me!

 

[Richard C]

Just remember raw plasterboard has a maximum weight of 32 kg/sqm & plaster just 20 kg/sqm which can be a problem if you’re considering large format/heavy tiles. Large tiles should also be fixed with powder adhesive & any plaster/plasterboard must be acrylic primed to avoid a reaction between the cement in the adhesive & gypsum.

Use only quality trade tiling materials of the correct type for your tiles, cheap own brand & DIY products are mostly crap.

 

[handyman77]

I would never recommend tiling straight onto plasterboard.

 

[tpt]

handyman - why not, its a great base - far better than plaster.

Just acrylic prime it first and your good to go.

 

[handyman77]

Ever tried to remove tiles from plaster board. Sister in law just had to have her whole bathroom reboarded cos someone was to lazy to plaster it.

 

[tpt]

thats exactly why they are a better base!

 

[tpt]

And not plastering it isnt lazy, by plastering it you are restricting the types of tiles you can use, because the max tile weight is lower.

Mostly when tiling you should be more interested in how well they will stay on the wall than how easy they will come off

 

[handyman77]

That s until you want to get them off

 

[Richard C]

Ever tried to remove tiles from plaster board. Sister in law just had to have her whole bathroom reboarded cos someone was to lazy to plaster it.

Sorry but your talking rubbish & I’m a plasterer as well as a tiler. If you’re stuck with plasterboard as a tile base, tile straight onto it unless it’s a wet area; but you shouldn’t be using PB in a wet area anyway. Plaster is not an ideal tile base as it significantly reduces adhesion & permissible tile weight; OK in years gone by where 6” x 6” tiles were considered large but it can be a real problem with the current trend towards heavy/large format tiles.

The fact that the PB was damaged in your SIL bathroom merely indicates the tiler did a good job & that the tile adhesive was doing its job correctly; a decent trade adhesive over plaster skim will just as easily remove the skim coat. If the tiles “pop off” the wall its incorrect/poor prep or cheapo crap/wrong type of adhesive used.

 

[McBain]

Sorry but your talking rubbish & I’m a plasterer as well as a tiler. If you’re stuck with plasterboard as a tile base, tile straight onto it unless it’s a wet area; but you shouldn’t be using PB in a wet area anyway.[/quote]

HI richard, just a we bit of info from you if you dont mind.

I Have to tile my mums bathroom. You are saying above that you should not be using PB in a wet area? SO what should I use??

 

[McBain]

Sorry richard I just relise that you get waterproof tile backer board!!

How do you put this onto the plaster board? do you screw it on or get some sort of glue?

 

[Richard C]

I Have to tile my mums bathroom. You are saying above that you should not be using PB in a wet area? SO what should I use??

I should have quantified that by adding “unless it’s tanked”. Plaster board is not ideal in a wet area & even if the tile base is tanked the reverse side will still be vulnerable to water damage if the shower uses a recessed mixer valve & concealed pipe work. If it’s a timber stud wall or dot & dab over brick then the plasterboard should ideally be removed & replaced with a backer board. You can use adhesive to initially fix & hold PB or backer board in place but if tiling over it should always be mechanically fixed or the whole lot could end up on the floor.

The cost of plasterboard + tanking will likely be the same or more than using waterproof tile backer board so that’s the best choice if you have the option but if your stuck with PB, tanking is a solution. It won’t, however, increase the weight carrying capacity of the original base though. For raw plasterboard this is 32 kg/sqm & for plaster skim is 20 kg/sqm, which includes up to 4 kg/sqm for the adhesive & grout; for this reason plaster is not an ideal tile base as it is unsuitable for heavy, large format tiles. Additionally, if you’re using tiles larger than around 250mm you will need to be using powder adhesive rather than tub mix; in this case plaster & plasterboard must be acrylic primed to prevent a reaction between gypsum & the cement in the tile adhesive.

 

[krismusic]

Wowee! This has gone off at a few tangents! I asked the tiler in the end and he wants tapered edge. Taped. As I don't want to keep asking him dumb questions, how many srews per board? I mentioned in my original post that the shower area is to be tile board. I am using Wedi. dam,n it is expensive! I do not want to use thier tape and fill system as it introduces an uneven surface for tiling. I have supported all the joints with studwork and am intending to seal the joints between boards with Stixall sealant/adhesive. Any likely problems? Thanks a lot.