Quick bathroom question

[Dammit]

Right, lets have another crack at posting photographs!

This is the ensuite, where the shower tray is going to go:

To the left is the cinder block/base plaster/finishing plaster/paint wall.
Directly in front is stud, soon to be covered in Aquapanel.
To the right is Aquapanel.

The wall to the left is the one that I am concerned about, now am I better boarding over it as discussed earlier, or chipping all the finish coat off (and thus taking the paint with it) as it has blown in some areas:

And again at the base of the wall:

If boarding it is the answer will the plasterboard bonding stuff adhere to the painted wall?

 

[Richard C]

The wall to the left is the one that I am concerned about, now am I better boarding over it as discussed earlier, or chipping all the finish coat off (and thus taking the paint with it) as it has blown in some areas:

Even if you chip off the finish skim coat, you might still be left with render base that is in poor condition or has poor bonding. It may not support the tile weight & be so uneven it will create problems, particularly with large format tiles; & we still don’t seem to know the weight of your tiles! If you have the space to accommodate the additional thickness of over boarding, I would just rough fill any problem areas with powder tile adhesive & overboard the lot but see below.

If boarding it is the answer will the plasterboard bonding stuff adhere to the painted wall?

Believe I’ve covered that in my previous post; you cannot rely on adhesive alone to hold the boards in place. Use adhesive to initially fix in place & level, then you must use through fixings or chances are the lot will end up in your shower tray. Additionally, an adhesive bond alone will only be as strong as the iffy plaster/render it’s stuck to!

 

[Dammit]

Hi Richard, sorry- should have made it clearer, I bought two boxes of those frame fixings you linked to upthread, and will use them to ensure that it's firmly on.

I was more wondering if the board adhesive would be sufficient to the task of getting the aquapanel to stay on the wall at all, and go off so that I can use the fixings the next day.

And, more to the point, if boarding was the answer, which it looks like it is.

 

[Richard C]

I was more wondering if the board adhesive would be sufficient to the task of getting the aquapanel to stay on the wall at all, and go off so that I can use the fixings the next day.

As long as you use sufficiently sized adhesive dabs on a 300 x 300mm grid pattern they will hold it in place until you mechanically fix. Put additional intermediate adhesive dabs around the edges of the boards for additional support.

And, more to the point, if boarding was the answer, which it looks like it is.

Unless the additional 15mm or so (board + adhesive) is critical, it’s the way I’d do it otherwise you will have to completely strip the plaster & render from the walls to give you a flat enough surface to take the boards. You should avoid board joints & tile joints coinciding; tape the board joints (I use ordinary plasterboard tape not the Knauf tape) & when your ready to tile, work some tile adhesive well into the tape mesh before you trowel on the tiling adhesive bed. The type of adhesive you need will depend on the size & type of tiles you use.

 

[Dammit]

That 15mm will mean that the board overlaps the shower tray by that amount, which may look a bit odd but there you go,