Shower tray fitting - unsure of plumbing

[lubemonkey]

Hi,

I'm hoping someone can shed some light on my confusion.

Our shower tray has failed by cracking near the waste. On ripping part of it out, I suspect it is because it has no support in that area (see pics). I've read a few tray manufacturer's install guides online and I always get stuck at the same part when trying to visualise the install in our bathroom.

All the guides I've read say fit the trap to the tray, fit the tray, connect the waste pipe. I cannot see how I connect the waste pipe with the tray in place.

Hopefully the pictures show my scenario ok.

I have thought of replacing the tray using a riser kit, but I think if the riser kit is high enough to get access to the waste, then the shower enclosure will be too close to the ceiling as there's only 120mm clearance as it is.

Any help much appreciated as I need to get this tray ordered asap (lucky me)

Cheers!

 

[TicklyT]

I can't see any signs of any bedding under your tray. It is the usual practise to set the tray into a continuous bed of weak mortar mix to support it evenly.

Placing the tray directly onto floorboards or a sheet of ply can lead to cracking from the load being concentrated on one or two high spots either in the flooring or on the underside of the tray.

Reducing the size of the hole in the floor around the trap to the minimum possible will help support the tray around what is probably it's weakest part.

There's nothing to stop you from fitting the trap after installing the tray, but correctly aligning the waste and getting all the seals in the right place and watertight can be problematic.

You could add a section of waste pipe to the trap outlet ready for convenient connection to the rest of the waste pipe run after installing the tray by working through a hatch cut in the floor clear of the tray position.

If the shower is on an upper floor, consider opening a hole in the ceiling below for access to the waste, and making good afterwards.

 

[lubemonkey]

Thanks for the response!

I can't see any signs of any bedding under your tray. It is the usual practise to set the tray into a continuous bed of weak mortar mix to support it evenly.

It's bedded on thick beads of silicone which you can see a few of where I've broken up the tray so far. The coverage looks a bit poor and it makes the old tray a bitch to get out!

Reducing the size of the hole in the floor around the trap to the minimum possible will help support the tray around what is probably it's weakest part.

My thoughts too!

There's nothing to stop you from fitting the trap after installing the tray, but correctly aligning the waste and getting all the seals in the right place and watertight can be problematic.

I still can't picture how you'd do that. At all.

You could add a section of waste pipe to the trap outlet ready for convenient connection to the rest of the waste pipe run after installing the tray by working through a hatch cut in the floor clear of the tray position.

I get this bit. I'll have to measure up but I can picture fitting the trap, fitting the tray then accessing underneath via a hole in the floor. In the picture the trap/waste pipe runs between two deep joists (suspended floor in loft conversion) so the only access would be to lift the tiles and cut the floor adjacent to where the waste hole in the tray/floor is.

If the shower is on an upper floor, consider opening a hole in the ceiling below for access to the waste, and making good afterwards.

It's above the original bathroom so possible, but will have to check logistics of that re: new suspended floor.

I'll take a look this evening - cheers!

 

[cantaloup63]

The cutout for the trap is way too big IMO.

A full bed of mortar should have been used, gently tapping the tray down and level using a rubber mallet. Beads of silicon are not sufficient, as you have discovered.

Since the trap is usually screwed into place by the grill from the top, you could get the main body of the tray in place with the trap housing in the right position below (supported so that it's only a cm or so from the underside of the tray) , then use the screw to "pull" the trap up into place.

 

[dweeble]

Thanks for the response!



There's nothing to stop you from fitting the trap after installing the tray, but correctly aligning the waste and getting all the seals in the right place and watertight can be problematic.

I still can't picture how you'd do that. At all.

You can get a trap that is in two parts, you fit the bottom bit to the waste pipe after carefully measuring where the hole in the tray will land, then bed the tray and connect the top part of the trap. you might have to pack the trap up to the height required. Sometimes easier to fit a flexible waste pipe to give a bit of play.

 

[lubemonkey]

Cheers for the replies - I get it now!