Shower tray issue...

[andyoxon]

Shower room has an alcove with 3 upstand tray which tends to leak at front right into the stud wall void. Shower door on front edge - with no base upstand.  Base is reasonably deep, & on legs mounted on wood blocks.  I've just removed the bi-fold door to reseal etc.  Should I consider getting a 4-upstand base (760mm sq), which is ~£120?  Would this be compatible with the door?  Also, I was thinking I could leave the shower tray in place, but fill the lower bit of the wall void with poly foam so that the silcone has something to 'push against'.  Wondering if the tiles at the side of the base don't have enough gap down on to the base so that not enough silicone to maintain a seal?

Any ideas?

[HTFB]

I can't quite visualise your setup, so this may not be relevant, but one of my proudest bits of DIY was entirely solving the leak into the wall from our no-upstand shower tray by loading 120kg of storage heater bricks onto it before applying the new silicone, so that when unloaded it remained in compression. Everyone knows to do this for baths, of course.

That tray was actually standing on wooden blocks instead of legs, and I think that allowed more flex than it was designed for. We have since then had the bathroom redone by someone who wasn't a cowboy, and it's much less fun.

[aidan.f]

There should be
18 mm +  Plywoood across joists under shower to form a firm support
sealant tape around the back edge of the shower tray and up under tiling/wall covering
https://www.bes.co.uk/aquastrap-seal-3-4-m-roll-20183/
This forms a secondary seal to the silicone
And use tile backer board not plasterboard under tiles
I appreciate all this advice is great if starting again from scratch
 

[Kim]

Similarly, there's this stuff: https://wickes.co.uk/Homelux-Bath-Seal-Pro-White-1-83m/p/229569

Fits behind the bottom row of tiles, and overhangs the bath (or presumably shower tray) so that it can move up and down with impunity and the water still ends up in the right place.

[andyoxon]

Thanks all.  I need to re-grout the lower tiles that sit over the side/back shower tray upstands, so could think about removing andputting some seal strip down.

I can't quite visualise your setup, so this may not be relevant, but one of my proudest bits of DIY was entirely solving the leak into the wall from our no-upstand shower tray by loading 120kg of storage heater bricks onto it before applying the new silicone, so that when unloaded it remained in compression. Everyone knows to do this for baths, of course.

That tray was actually standing on wooden blocks instead of legs, and I think that allowed more flex than it was designed for. We have since then had the bathroom redone by someone who wasn't a cowboy, and it's much less fun.

Looks similar to that bifold door link image; except that the non-shower room space is the width of the door & shower cuble square.  The tray is not low profile.  Thanks for ply tip - may try and get some thick marine ply to reinforce.  Also have some heavy concrete blocks (which gave me a frozen should last Xmas), which I could carefylly use to weigh base down, after reinforcing & before sealing...

[Blodwyn Pig]

I have had good success in the past by cleaning out the mastic that abuts the shower tray/tiles,and re masticing with clear silicone and one of those mastic tools. I find clear mastic far more useful in sticking and staying sealed, than the white stuff. When all done and its dry and cured, then a strip of small white plastic self adhesive quadrant, stuck to the tiles ,  and mitred in the corners, then when stuck firmly, run a bead of white silicone along all edges, then finish with silicone finishing tool.  The quadrant deflects all the tumbling water with ease, and any water that manages to get past (shouldn't be any) has no pressure or force, so the abutment seal is good to go.

[Feanor]

I found this instructional video quite good when I had a similar job to do:

https://www.youtube.com/watch?v=_DI4hfHM_Hg

Things to note:
1) Use the profiling tools;
2) Use Low Modulus (flexible) sealant if the joint is liable to move
3) For things liable to move under load ( baths when filled with water, shower trays when filled with people ), apply sealant with them under load.

[DaveReading]

shower trays when filled with people

Too much information ...