Fill Chased wall

[blastedfury]

I've chased out the wall to put in pipes for a new shower and to sit the shower valve in. In some places the i've chased out up to 60mm mainly around the shower valve.

What would be the best material to fill in the wall, I don't need a perfect finish cause i will be tiling over.

 

[Richard C]

Bonding plaster; but give it a sealing coat of PVA the day before you tile or it'll suck the adhesive dry in seconds.

It’s usual to leave the area surrounding the mixer valve clear to allow for any future maintenance access, just covering with tiles & then the mixer plate. You can also bridge over pipe chases with tiles if the positions allow but 60mm is rather wide! & the pipes obviously have to be securely fixed!

 

[blastedfury]

Thanks for the reply.

What i forgot to mention was the chase is 60mm deep in places. Is bonding plaster still the best option or would a sand cement render be better?

Can i apply it all at once or do i need to build up in layers?

 

[Richard C]

You could use render but, personally, I would stick with Bonding plaster as you will find it much easier to use. When used as a surface base coat, Bonding should only be applied in coats of around 11mm thick, allowing each to “go off” before applying the next coat, exceeding this causes it to crack & craze. The maximum recommended overall thickness is also 25mm but, again, this primarily applies to use as a surface base coat, it should be OK as a chase fill. Build it up in, say, 4 or 5 layers applying the next just as the previous starts to go hard but do it all in one session (while still wet); once you let it dry out, it will have to be thoroughly wetted or sealed with PVA or it won’t stick.

Bonding should not be tiled directly onto; narrow pipe chasses & small areas around the mixer valve won’t normally matter but yours seem rather large; I would give it a final coat of Multi–Finish around 3mm thick or at least PVA seal it before tiling.