Which parts of shower trap need silicone?

[ChrisKingston]

Am near to finishing a marathon to get to first fix for bathroom and am going to fit the tray with waste and trap. Trap instructions say I should seal with silicone, but I'm not sure exactly which bits to do.

I've drawn the trap and labelled the four gaps which could be sealed:

Untitled

• ChrisKingston
• 7 Aug 2011
• 1

I'm pretty sure you're not supposed to do Gap A as this one's supposed to unscrew to get at the trap if you need. But what about the others?

I've got no access to the underside unfortunately, so I'll have to do it all in one go when I mortar the tray in. This means if I silicone in Gap C or Gap D it will have to go in, rather than around, the seal.

I was going to use Dow Corning 785.

Thanks,
Chris

 

[rego]

i would get rid of top washer and use plumbers mait. i would silicone gap c

 

[DP]

I would say no silicone required. It is dry assembly. What did folk do when there was no silicon or PTFE.

 

[ChrisR]

Nothing on A or B - it doesn't matter if those leak, the water should still go down the waste..
I'd put a smear of silicone on C and D. I've repaired a load which were put together dry, or with plumbers mait.
Silicone might be "not required" according to some folk, but it works!

Plumbers mait is a pet hate of mine,
Doesn't stay stuck, goes hard, difficult to clean off, no resilience, horrible stuff. They used to make houses with horse dung and straw. We've moved on.

I wouldn't choose a waste flange ("plughole") like you've drawn, because you have to remove the fixing to the tray whenever you clean it. Look for one with a removable inner - the flange stays put.

 

[Nige F]

I would say no silicone required. It is dry assembly. What did folk do when there was no silicon or PTFE.

Hemp - with or without boss white

 

[ChrisR]

Not for this Nige, putty and paint, surely? A goddawful mess if there ever was one!

 

[Charnwood]

Logically C and D, but why would the manufacturer supply a rubber washer for this gap if its going to be siliconed? That, in effect, makes 2 gaps that need sealing.

If A or B leak water will go into the trap, so no need for silicone.