Replacing Shower + Base

Hi all. I'm replacing two showers I have in the house and would like some advice. I'm going from a 800x800 unit to 900 x 900.

1) The new showers have acrylic walls so once i remove the current tiled wall and replaster it, will i still need to waterproof it even when the acrylic walls will completely cover the plaster? I plan to cut out the old plaster and install waterproof boards but would this be overkill since i'm not staying with tiled walls?

2) If i dont need to replace the boards, do i need to worry about the extra 10mm which probably isn't currently waterproofed?

3) I'm retiling the floor so is it ok to glue the base to normal cement sheeting that i'll use for the tile underlay? I went under the house to have a look and it doesn't look like mortar to me but every thread i've read here its been recommended a mortar bed to be laid. If I cant use cement sheeting then is it possible to buy premaid mortar sheets or would I have to mix up the mortar myself?

Any other advice would be greatly appreciated.

Thanks.

First I would re-sheet the wall with villaboard, these arcrylic shower kits come with a glue that recomends villaboard, over time it will just peel off the plaster.
With the few that Ive installed I havent worried about waterproofing the walls but the unit must be well sealed, using kitchen and bathroom silicone, which brings me to the next point, the base.
The first one I installed was on a bed of sand and cement, it ended up moving then it would 'crunch' under your feet when you walked in. Since then Ive used liquid nails with no hassles. You then must seal the perimeter of the base with sikaflex, then waterproof your floor.
Then you will need to screed a sand and cement bed for the tiles, the compressed fobro floor sheets move around too much to simply glue tiles down, all the grout cracks and falls out then your tiles crack and/or become loose. And yes you will have to mix up your own mix. Give it a go, it will be an adventure!:2tsup:

Thanks again for your feedback.

From my reading, villaboard is 6mm thick compared to 10mm gyprock and what people usually do is tile over the villaboard which brings it to roughly 10mm. I have a feeling i've got 10mm gyprock at the moment so it might be a problem. I suppose the choice between villaboard and the gyprock for wet areas (cant remember the name) is a matter of preference and both work well. I'll have to see what's in there now. If its 10mm stuff then i'm just going to stick with 10mm boards.

With the base, i've read that some people use a certain type of adhesive rather than liquid nails but i cant remember the reason. Anyway it seems like I'll need to lay a mortar bed regardless. Is it really necessary to have a mortar bed? Doesn't seem like it does anything except keep it from moving.

My tiles currently are stuck onto sheets of ceramic underlay and I haven't had a problem with it so i might stick with the sheets because its easier and quicker. Although my bathroom isn't big, i've never done any screeding before and i dont want to risk having an uneven floor.

What you do is pack out the wall studs to make up your 10mm, imagine looking at your wall stud with the 2" side facing out, simply pack out that 2" strip. Im not sure what you would use but one of the chippies might be able to help.
BTW an uneven floor is the whole idea of it to get the water to drain to the floor waste, it really is quite simple.

I read about people packing out the studs but some people say waterproof gyrock is the same as villaboard so it all comes down to preference i suppose.

The only floorwaste I have is in the shower for which i've bought a prefab base. I'm going to rip it up 2moro and see what the condition of the mortar bed (if it even has one). My question was more directed at the floor tiles which wont really get wet. I've spoken to the tilers and they recommend cement sheets so again, different suggestions.

I've just had a look under my old bathroom sink and the taps are connected to the water pipes via these long pipes without any valve/taps so its just a pipe straight to the cold tap from the wall and the same for hot water. I'm going to get a mixer for the new vanity and i wanted to ask if its necessary to install a shutoff tap in between the mixer and the wall pipe or do i just connect it up with the braided lines that come with the mixer?

You must have isolation cocks (mini cocks) under any basin or sink that has a mixer tap installed, same as bath and shower mixers must have their own isolation valves. Besides, its good practice.