Stone resin shower tray seal

24 Nov 2020
Reaction score
United Kingdom
Hi ,
I've just done the first fix on my ensuite and have just taken delivery of a 1400 X 900 black resin shower tray .
The tray came with a mcalpine waste and flexi adapter .
The wastes in situ and I've got a fall of around 40 mm over 2m .
My concern is the finish on the underside of the tray , it looks like pebble dash .
The washer on the trap is a fair thickness with ridges in it but I'm really concerned that it won't seal .
Looking at the design am I right in saying that it's only the top face seal that matters and the bottom seal shouldn't come into play as water won't get to the seal height as the exit hole in the trap is below this level ?
I'm tempted to put a bit if silicolne on it .
Thanks for any advice


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I'm not a fan but a smear of silicone won't do any harm.
Only my opinion but, get a tray with a flat contact area around the drain hole
I'd also loose that flexi waste pipe and replace the chip board.
As you can see the 'stone' has been ground flat around the waste to give a better finish, one of the reasons there a nice thick seal too. A little sillicone to fill the gaps should do the job.

I would agree to lose the flexi, it will sag over time creating a dip where the water will gather causing problems in the future. Hard pipe it from the trap and support it properly.
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Thanks guys , I'm an engineer not a plumber so any advice is much appreciated .
I was going to but some bits of timber under the Flexi to stop the sag but I get what you're saying about it .
You can see where they have dressed the tray , it's just not that good of a job and unfortunately I'm stuck with the tray .
Thanks again
The bottom seal matters more than the top one, if the former was sealing properly no water can escape even if the inner seal wasnt there, not advocating not sealing:) , If the top was sealing properly and the bottom one wasn't then the water could get past the threads holding the two parts together and escape .
With the right skills the seal contact area could be improved somewhat to avoid too much sealer.
An orbital or flat sander could be used to smooth out the raised areas, if they are overly bumpy but looking at it, that's already been done. As long as the seal contact area is flat then it should be fine, just ensure the seal is set into the lip of the trap properly and a little silicone is used, not too much. Don't overtighten the waste when locking it all together.
Thanks guys , I dressed it a bit with a diamond hand pad ,worked a treat .
I dry fitted it without silicolne and had it running constantly for an hour ,seems fine .
I find silicon on any joint allows too much movement and over tightening can squish the seal distorting it , less likely with a dry joint.

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