freshly skimmed plasterboard... drying and tanking

[mwebber.82]

Hi,

I'm fitting a shower enclosure in a freshly plastered room and after several hours scouring the forums I think I'm getting there! I just need to clarify a few things that I can't find answers for myself...

1. how long should I leave the skim to dry out? the plasterer was back today to finish some other bits and he says it's good to go already! 1 week later? it does 'look' dry...
2. do I need to prime the plaster skim before tanking? I've seen other posts referring to acrylic primer but those posts tend to be talking about bare plasterboard rather than skim...
3. do I fit the shower tray in place before tanking, or should I tank down to the floor and then put the tray into place, and seal it in with mastic or similar?
4. I'm using ceramic tiles 30x40cm - I had bought some all-in-one ready mix adhesive and grout from wickes... I'm guessing from what I've read that this would be frowned upon! Any suggestions?!

Thanks for all your help!

 

[Mouldy]

1. If plaster colour is light pink then itll be good to go. A skim is only 1-2mm thick and will take no time to dry throroughly on a PB background.
2. Depends on what tanking system your using and also depends on what the manufacturer of said tanking say on the instructions!
3. tank before fitting tray then seal off tray to tanking using Silicon
4. AVOID all in one systems! Use a proper adhesive and a proper grout.

 

[Ian]

As above, to elaborate on the adhesive side of things, use a powdered, cement based adhesive and a powdered grout. All in one should be avoided, its not suitable for what you are doing.

 

[White Room]

Fit the tray before tanking

 

[doug boardley]

most definitely use an acrylic primer on plaster.

 

[brinkley]

whitebeam why do you say fit the tray before tanking surely by tanking the whole wall you have a seamless finish (not picking holes just curious )

 

[aph257]

i also would fit tray before tanking so that you run the tanking tape from wall to top of tray, (and also up the corners) then tile, then trim any tape thats shows, then Silicon the gap between tile and tray.

 

[Mouldy]

mmmm. Not sure I get this either.

Tanking has little elasticity. If the tray drops or moves, (which I have read here seems to be the reason for tanking showers in new builds), then the water seal is compromised because the tanking will pull away from the tray.

If you tank the area first and then fit the tray and seal with a high modulous Silicon then if there is movement the Silicon is less likely to break away from the tray then tanking.

Maybe Ive missed something here and Im not criticising the above methods, just trying to understand! Should also add that Ive never tanked a shower area, (wet floors and areas notwithstanding!!).

So then guys and gals, show me the way to the promised land! :smilewinkgrin:

 

[paul damian]

welcome to the tiling forum, is the shower area plasterboard aswell, why skim when you are tanking ,, you are now reliant on the adhesion of the skim to the plasterboard, instead of the mechanically fixed plasterboard. In other words the skim is taking all the weight. Shower tray installed first, tanking is meant to lip over shower tray .

 

[brinkley]

im lost how is tanking supposed to lip over shower tray former yes but tray not sure on that i shall carry on my way till i see proof that this is better

 

[White Room]

Some trays have to be bedded into the wall and the plumbing has to be sorted before tiling..

I have never seen a tray fitted after any tanking

 

[brinkley]

i prep my shower walls including tanking before shower tray is fitted perhaps its just me but i see this method of fitting well in my mind it just seems to work better

 

[aph257]

I can see both ways suit different situations/methods. each to their own

 

[cornish_crofter]

Wickes Fix and Grout should actually be banned. It is only every going to work in kitchens.

When I came across this forum one of the first things I did was to ditch all my DIY shed gear. One of my customers who wanted to tile his kitchen got the better stuff, the rest hit the bin.

I did start using good tubbed addy (BAL Greenstar etc). However I have now moved onto bagged stuff apart from the very small jobs where waterproofing is not an issue and it's quicker to get a tubbed addy out. Also I'm not using it on tiles more than 150 x 150. I have actually used the cheap weber on mosaics with great success. A good substrate etc and where it is unlikely to get hit by shedloads of water. Areas were part of the bath panel onto Aqua panel and the basin splashback. That was only because I had it and I was too tight to go and buy some more mosaic fix.

Grout - ready mixed shoud join that rubbish from Wickes in room 101. Bagged every time now.

Tanking before or after shower tray. Different situations suit different people. I have used Aquapanel several times for showers. Whilst it's perhaps not in the same league as Wedi board, it has never let me down. I taped and sealed the joints but I never actually tanked Aquapanel. To that end the Aquapanel goes in BEFORE the tray because it forms part of the wall.

However, if you are tanking separately, I can see how tanking can work if it goes on after the tray is fitted.

When I fit a tray and tile the walls having fitted aquapanel, I use a 2 seal system. The first seals the tray against the wall. Then the tiles go on, then another seal goes between the tray and the tiles.

A good quality Silicon line Dow Corning 785 works for me. In fact I won't use anything else now. Use it right and you tend to only need a couple for the average shower. Expect to pay around £5 per tube.

 

[mwebber.82]

Thanks all for your help. I'm learning fast!
The reason it's skimmed is that I needed to get my plasterer freind in quick - before I'd started researching. He reboarded some sections with green moisture resistant board and then skimmed the whole room. It was only after he'd done it that I looked into the fine details (that was lesson 1!). It made sense in advance in that I knew I was only tiling up to the top of the shower and painting above, so skimming higher up seemed to make sense!
I've primed, tanked (down to the floor - old house, movement and cracks appear relatively regularly!) and now ready to tile.
Thanks for your help!

 

[Mr Tiler]

does any of the room need skimming if its all being tiled? or does bare plaster board suite fine?

 

[White Room]

The post is 3 years old mate....

 

[Mr Tiler]

can be brought back up cant it? they are saying that basically the wet area doesn't need to be skimmed so that has laft me to think if a room has been re-boarded does any of it need to be skimmed lol

 

[beanz]

Interesting thread. I've never given any thought to the elasticity of a tanking membrane.. I've always fitted the tray 1st, siliconed it to the wall, then tanked, tiled, and siliconed again..
in answer to your question T-Bag.... If the room is being fully tiled, there's no need to plaster, but if some areas are being tiled, and some not, it can sometimes be easier to just plaster the lot. Some people just get it plastered without giving it a second thought. Turned up at a new build once, and they wanted all bathrooms fully tiled with Trav, Marble, and Limestone. They thought they'd helped us out by getting it all plastered first..... :banghead:

 

[Mr Tiler]

thanks beanz