Shower Tray Install On Timber Floor

[AliGage]

Not much to tell really, I asked about it in another post, basically I was advised not to stick tiles directly on to green chipboard, but can't afford to raise the floor by much, so thin ply seemed to be the answer, ( well screwed down of course ).

Which thread is that? Can't see anyone on here recommending this ply. 6mm hardiebacker would be the recommendation.

 

[StephenR]

What @StevieBoy sez. Shower tray manufacturers almost always advise sand cement mixture. I install about 5 or more a year this way so about 50 or more trays in all. If over floorboards, 12mm ply over boards first. If you can't take the hight increase, remove boards, then 18mm ply with noggins to support edges, then sand cement with tray over top. Sand cement gives you the opportunity to level up after the first time you try and it isn't level whereas adhesives, glue, silicon etc doesn't. Real world means the floor is rarely level enough.

cheers,

Stephen

 

[weirdfish]

Which thread is that? Can't see anyone on here recommending this ply. 6mm hardiebacker would be the recommendation.

They didn't recommend the ply, but the hardiebacker would create too much of a step into the en-suite.
If I can't go straight on to the green chipboard then a layer of ply is my only choice.

 

[StephenR]

Going over chipboard will be fine if there is no flex in it i.e screwed down and supported well.

 

[weirdfish]

Going over chipboard will be fine if there is no flex in it i.e screwed down and supported well.

Even if it's the green waterproof chipboard?

 

[StephenR]

Green chipboard should be fine if well supported. You got a big heavy tray there. 15mm or so of sand cement. If it has recessed back, then maybe more to start. Don't let the tray be supported by the edges only.

You'll need two people to man handle that thing into place. The mix shouldn't be too wet. Comb it out so there's a bunch of peaks and valleys. Make sure it is level in all directions. Sometimes I stand on it and wiggle it back and forth to push down the high bits but on something this heavy, you can probably just wiggle it with a bit of pressure on the high bits. Too dry a mix and you'll struggle to level it.

If this doesn't work first go, lift it, see where the hollows are and bits that are well packed down, move the packed down bits to the hollows, comb it out again and pop the tray in for another go. This is the advantage of sand cement. You'll be unlikely to lift it if you're using adhesive, glues, silicon and the like. Check levels along edges and diagonally. And also many trays are not totally flat along the edges which doesn't help.

Modern big trays with a low profile have minimal slopes so once in, check the falls in the tray to ensure that it goes downhill to the drain. Sometimes the middle drains to the edges first before the edges slope downhill. A water test is best to see it drain. You want to avoid puddles but don't get confused between a puddle and surface tension on these small slopes.

Hope that helps and isn't too confusing. Watch a Youtube video. There must be one out there some place.

 

[weirdfish]

That's helpful, thanx.
When I mentioned ply it was to do with the tiled area of the en-suite, hence why I thought that you couldn't tile straight on to green chipboard.

 

[White Room]

What is?

Sand/cement....

 

[StevieBoy]

Sand/cement....

The same stuff they use to hold bricks together when building houses?

Not being funny, but you'd have thought if it'd hold a house it'd hold a shower tray, just my opinion.

Maybe this is one for a plumbers forum, as I said before I'm no expert on this sort of thing.

 

[Drainage by Design]

It's here, blimey it's heavy, ( it's 1700x800 ).
It's not flat on the underside, it's got ridges.
Is it best to use adhesive, if so which one, remember this is going onto the green waterproof chipboard.

Chipboard is not WATERPROOF - the vesion you have is the chips bonded with a water resistant glue.
The wood chips will still absorb water.
The safest way to install the tray is to tank the floor - plenty of good brush on/roller apply products OR sheet products which are bonded to the floor and coved up the walls. Tank the walls, too, for the sake of a little extra time.
Then bond it with the tile adhesive others have recommened.
If it sounds like belt and braces, it is a lot better value than discovering the celing below is brown......