shower waste through timber floors help?

[mutley racers]

Hi, I am needing to know what kind of trap to use on my shower tray. As it is going though 18mm ply and then 12mm ply on top. So it needs some depth. Also, I need to be able to connect it begoe putting it in place. So with a flexible waste as I can't get to waste through joists. So will need a flexible waste or something. The waste the shower tray has come with does not seem to have enough depth on its outlet to get through the floor structure to connect the waste pipe.

I hope that makes senses

 

[AWheating]

mc alpine do a good range. even one that connects at the bottom.

90mm Shower Traps - Traps | McAlpine Plumbing Products

 

[Best]

Agree, Mc Alpine traps. The bends on them when turned downwards obviously drop away from the floor, so there will not be a problem hitting the floor but you probably will have to cut a bit out of the ply floor where the waste bend is. You may wish to use a square bend to then join level from the angled waste bend.
Tip for doing all this is to set the tray in it's exact spot & mark the waste hole on the floor. Remove tray & mark a very large cross through centre of circle - so you never lose the centre mark after cutting the hole. Cut the floor a bit bigger than the outside of waste fitting including a bit above the bend if it has a high bend. I would put accurate wood supports in below the waste to hold it almost to it's needed height. Check the waste is dead centre on your cross & you can't go wrong. All you have to do is bed the tray & tighten threaded waste into the trap from above.

 

[mutley racers]

Thanks for the replies guys. Mcalpine trap it is. when you say bed the tray, do you mean with sand and cememnt as mine is flush all around the botton, apart from the kind of moat. Also, you say just tighten from above, but how do you know if you don't have a leak as it is not possible to check when the floor is down and all joists in the way. is it just a case of a silicone on the threaded flange to the shower tray

 

[mutley racers]

so basically, all you really do is cut out the shape of the trap with the bend into the wooden floor? I was worried that this would weaken the floor. But, as the shower trays load is spread, it wont really effect it much

 

[stevetheplumber]

best to put nothing on the threads these traps are pretty near fool proof silicon tends to allow the washers to twist out when tightening and its unnecessary
you realy only need to bed them on something if the floor is uneven when they are down on clean board i just silicon the edges

 

[AWheating]

should be fine, chipboard floors are the worse for strength after cutting a hole, if it weekens then cut a large section out and replace with 18mm exterior ply bracing any joints. You may be better to bed the tray on extra flexible tile adhesive.

as soon as the tray is in and trap sealed run plenty of water down it to give it a good test.

 

[mutley racers]

Cheers AW.

 

[mutley racers]

oh really steve, The mcalpine trap that came with the shower said to add silicone to it? I think i will go with that steve, the floor is level and its a proper resin tray. Not a plastic one. So heavy it is

 

[Best]

Usually I find even on the most level floors you need to bed the trays unfortunately.
I like that idea of extra flexible tile adhesive - much better & easier to bed tray than sand & cement.
Cut the hole in the plywood for the trap rounded, so not to weaken floor too much.
If possible, have a trap in the floor to view the finished waste to check for leaks when you test tray with a lot of water, but often you will just have to do a fussy job & you will be sure it is sound.