Plinth

Planning a bathroom conversion - need a 1600 x 700mm shower tray. I need it raised about 5 inches off a T & G floor. Would rather have a plinth than legs. Any recommendation on materials for spacers and for a top surface. I realise "wood" is a simple answer - but just concerned about long term shrinkage and distortion. Any particular types I should aim for?
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On 13/05/2019 10:43, DerbyBorn wrote:

Mine sits on offcuts of flooring joists from an old job, so treated timber. Having seen how quickly a tiny leak in a sealed space under a bath resulted in dry rot. For the surface I would use 18 mm shuttering ply. Think seriously about access to the trap and/or something like a rodding eye for extracting the stuff that will certainly thrive in the drain pipe.
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On 13/05/2019 11:28, newshound wrote:

Many shower wastes have parts that can be pulled out from the top for cleaning, leaving the pipe opening exposed for cleaning out. Access from below is only required when fitting, sorting a leak or replacing - which I hope won't be necessary, but would simply mean that I cut a hole in the ceiling directly below and then fitted one of the small, plastic, access hatches or made good and repapered that ceiling.
SteveW
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I've never quite understood why the excellent idea I saw in a hotel many years ago is not done. The whole thing was hinged and had easy to detach hose connections, so cleaning the trap and all that was easy. around the edge was some stuff like that you get around double glazed windows and doors if it perishes you shove in a new lot.
Brian
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In over 33 years in the house I have never cleaned the bath trap. Using gels and liquid soaps means no scum (and the tiles stay shiny)
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Do you think short off-cuts are better than full length? Less likely to warp?
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On Mon, 13 May 2019 11:28:32 +0100, newshound wrote:

I'm changing to no trap inside and a waterless trap outside (having tested it at low temperature to make sure that it doesn't freeze shut). I'll use black pipe, to resist UV, with about a foot of black downpipe to cover the trap.
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On Monday, 13 May 2019 17:43:34 UTC+1, PeterC wrote:

That'll stink, you need the trap right at the tray.
NT
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On 13/05/2019 10:43, DerbyBorn wrote:

bed it on sand and cement and tile the edges
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On 13/05/2019 10:43, DerbyBorn wrote:

If the wood is properly seasoned prior to installation, then it ought not shrink any further. I would use pressure treated 4x2 for the basic framework, with a top layer of 19mm WPB ply, and then if its a stone resin tray, bed that onto a half inch screed of sand and cement - probably with a bit of SBR in there as an admixture.
When installing the tray, butter the wall facing sides with silicone, and rule off the bead cleanly at the top edge of the tray. Then tiling / boarding - bring those down toward the tray, but leave a 1/4" gap, to later fill with silicone. Having a wide enough bead ensures it will get good adhesion, and also will tolerate any small amount of movement.
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Sounds good - thanks
I was thinking of getting a 1700mm tray and that would need chopping into the wall as is the bath it is replacing, The space is about 1680mm. I am now thinking this is additional work for no real benefit and am now thinking of a 1600mm tray. This will leave a small gap to be dealt with.
Do you think it is a better way? Any thoughts on the "gap"
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On 13/05/2019 17:44, DerbyBorn wrote:

Chopping a bath into the wall can be worthwhile - its a way of making a lighter weight acrylic bath far more rigid. For a shower tray there is no real advantage unless you need to do it to squeeze in a slightly oversized tray.

It sounds like you will end up with 80mm of gap. The tiles (depending on type) could take up say 30mm, which leaves at least a couple of inches. So perhaps some 1" deep battens on the end walls, and a sheet of aquapanel or hardibacker fixed to them to bring the walls out to the right spacing?
(that might amount to more work that chopping the tray in 10m on each end!)
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Long term leakage risks?
Handling a heavy tray into the chopped out walls - difficulty in replacing it if ever needed?
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On 13/05/2019 23:29, DerbyBorn wrote:

No different, I would expect.

Slightly more awkward to handle, but still doable IMHO. Use much the same technique:
Chop out a bit higher than needed for the height of the tray. plus a little more at the front.
Mix your screed and lay it on the ply. get it roughly level. Lay a couple of lengths of 15mm plastic pipe in the screed running front to back - they want to be the depth of the tray and another 4 to 6 inches long. With help (for that sized tray), offer the back of the tray on the edge of the platform - the pipes will take the weight and keep it clear of the screed. Now lower the front and slide it back into position - it slides easily on the pipe. Finally pull out the pipe to drop it on the screed, slap a level on it and tap it home with a rubber hammer etc.

A bit more of a pain - since once the tray is in place you will need to make good the plaster etc down to the top of the tray, and that will lock it in place. However there is no real need to get it out in one piece, and with stone resin trays its easy enough to break the edges off with a quick clomp from a hammer. So the centre bit of tray can come out, and then you can pull the edges free.
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