Installing shower tray with upstands

[GB]

Installing shower tray with upstands - this seems to be a right bastard of a job. According to the destructions, you are supposed to install cement board down to the floor, then chip away 5mm from the face of the board to a height of 115mm, so as to inset the shower tray and upstand. I spoke to Mira's technical helpline, who said: "ask your builder, as he'll have the right tools for the job".

The destructions show this being done with a hammer and bolster. Well, I have those, and it's not going to work, is it?

I'm using 12mm Aquapanel cement board, btw. The only way I can see to do this is to add a second 5 or 6mm layer of cement board on top of the Aquapanel, stopping 115mm short of the floor. Thus neatly doubling the cost and the work of preparing the room.

My impression is that most shower trays don't have upstands. Is this why?

[Roger Hayter]

A very recent thread in this group about this problem suggested simply removing the bottom 115mm of the board (PB in that thread) and leaving a moderately deep gap in front of the basic wall structure. I can't see any great problem with this approach, especially if the underlying wall is not too vulnerable to water damage. But i've never tried it.

[GB]

There's a 1.5" gap behind the cement board, apart from where the battens are. So, that's an issue.

The correct way to do this, apparently, is to remove the 5mm, then flood the gap between the shower tray and the remaining bit of the cement board with silicone. That sticks it all together and makes it rigid, as well as water-tight.

[leenowell]

Is the idea that the upstands sit against the wall (5mm inset) and then the tiles sit over the upstand? If the 5mm is to enable the silicone to sit be tween the upstand and the wall to the required thickness, could you just si licone it to the wall and let the tiles take up the extra 5 mm?

[GB]

The tiles are mean to overlap the upstand, inside the shower tray. To get that effect just by build up the tile adhesive layer would mean it would have to be an extra 5mm thick.

[leenowell]

The 5mm to me seems more about the thickness of the silicone holding upstan ds on than the measurement itself. I would put a load of silicone on the up stands/ base and squeeze it as tight as possible onto the wall. Given the h eight of the upstands aren't that much (assuming the tiles are much bigger) you may be able to get away with a thinner bit of tile adhesive just on th e upstand and keep the rest normal.

A bit (maybe a lot) of a bodge might be to silicone the bottom of the tile to the upstand to save the extra 5mm of adhesive all the way up the wall.

[John Rumm]

It would be ok on a solid wall - not so easy to do in the thickness of some aquapanel... You could do it will a wall chaser - position both disks side by side to get a wider kerf, set the require depth of cut, and then make several passes to chop away the required thickness.

Alternatively you add packers behind the aquapanel to bring it to the right position (i.e. inner face just inside of the upstand) and only bring it down to the tray to finish on top of the upstand.

(you could then add some additional offcuts of aquapanel to bridge the interface on the outside and silicone that on to add an extra layer that bonds the main aquapanel to the outside of the tray.

The instructions show the upstand thickness at 10mm... If so that is not far off the thickness of the aquapanel.

Probably one of the reasons!

[Tim Lamb]

I hit this with an Ideal Standard shower base. The upstand was moulded a few mm in from the tray edge so I had to notch the wall. Fortunately hard wall plaster so easy to do.

I doubt the tray is 115mm deep. AFAIR my notch was about 35mm wide. Good luck!

You could glue thin battens to the back of your showerwall and then glue the assembly to your cement board.

[Tim Lamb]

In message , Tim Lamb writes

Ah! Tiling. Sorry.

>

[Tim Lamb]

Umm. I think that 10mm is the inside upstand to wall distance.

The suppliers are quick to offer a tape substitute.

[stuart noble]

I wouldn't fancy doing anything much to cement board. It's full of reinforcement mesh, and not designed for what they're proposing. OTOH it could work with moisture resistant chipboard, which is actually damned near waterproof IME.

[harry]

That is not what is says at all. For solid walls it says to chip away the plaster. Easy with a hammer and bolster. OR For stud wall it says install cement board. This is all about stopping water running down the wall and getting under the tray.

[John Rumm]

Presumably you want the tiles to have their rear surface just inside the upstand - then you can seal them to the tray, and any water that gets past that seal encounters the upstand.

(what happens to it then I am less sure about!)