Leaking shower tray - Silicon advice please!

[Deleted member 49599]

Hi all,

I'd love some advice please. I'm re-sealing a shower tray that has a little bit of flex in it. The flex is minimal, but the old seal I did previously wasn't done perfectly and if a heavier person has a shower then the joint between the shower tray and bottom tiles would let a few drips of water through. I've removed the old Silicon completely and prepped the area and just wanting to make sure I do it better this time.

I've been watching some videos and one of the tips is to use a low modulus Silicon for joints that have a little bit of flex. However, I've been searching and searching for bathroom Silicon that is low modulus and haven't found anything. It seems that the only low modulus Silicon on the market is for general building use rather than bathrooms.

One of the additional problems is that for sealing around a bath one of the tips is to fill the bath with water first before applying Silicon to avoid the flex breaking the seal, but you obviously can't do this with a shower. I'm planning to put a load of heavy things in the shower tray before applying the Silicon to get it to set whilst the joint is already a bit flexed which isn't ideal but is the best I can think of. I've got a fugi tool so hopefully the seal will be better than before anyway.

So basically I have 2 questions:
1) Can I buy low modulus bathroom Silicon? If yes, where?? If not, what is the best Silicon to use in this situation?
2) Any other tips for improving shower tray Silicon other than my current plan?
3) When doing the corner (I have a vertical joint in the corner of the tiles and two horizontal joints where each side meets the shower tray) what is the best order to do the Silicon? Is it best to do vertical then the horizonals?? And is there a direction that is best?

Thanks all very much!

 

[Bond]

I have used a low modulus sanitary Silicon recently it was by a company called Soudal, the Silicon was called Silirub A. As good as any other l have used.

As to the order of application it does not matter, the main thing is to get a good application as deep as possiable,( the more you have in the joint the more movement it will accommodate.

 

[Deleted member 49599]

Hi Bond, You're an absolute star I looked for ages but that's exactly what I'm looking for, thank you! You didn't buy this from a shop by any chance? I'll order online if I have to but would ideally buy from a store so I can get my bathroom back to normal rather than waiting for delivery!

Thanks again!

 

[Bill]

I use a Dow Corning 785 Silicon as my go to. Tremendous product.
Dow Corning 785+ Bacteria Resistant Sanitary Silicon White 310ml - https://www.screwfix.com/p/dow-corning-785-bacteria-resistant-sanitary-Silicon-white-310ml/58308#product_additional_details_container

 

[Deleted member 49599]

I use a Dow Corning 785 Silicon as my go to. Tremendous product.

Hi Tom - I know this has a great reputation but I think it is not low modulus - do you know if they do a low modulus version?

 

[Flintstone]

If there is movement, your up against it really. I think what your going to do sounds about as best you can do. Make sure it's all clean, use the fugi and get a bit of a thicker bead, perhaps 8mm. Good look with it!

 

[Bill]

Ideally, you should have a gap between tile and shower tray to accommodate the Silicon. If not, just make sure you do not take off too much Silicon when using the fugi kit.

As for the actual application, just make sure you squeeze the Silicon right into the gap and use plenty. Once applied, use a spray bottle filled with a little washing up liquid and water to act as a barrier for your fugi (or finger or any other tool - the pro's use wooden sticks they have made themselves) then slowly drag the tool along the Silicon joint. You will have lots of excess material but don't worry, this is normal and it should just be able to pick up and dispose of because of the washing up liquid spray. I start with my vertical joints first but I do Silicon all joints before spraying.

 

[Andy Allen]

Low modulus mastic is more for exterior use.....
Imo you need to stop the tray from flexing or the problem will just keep coming back no matter what mastic is used..... They all have limitations..

 

[Bond]

Hi Bond, You're an absolute star I looked for ages but that's exactly what I'm looking for, thank you! You didn't buy this from a shop by any chance? I'll order online if I have to but would ideally buy from a store so I can get my bathroom back to normal rather than waiting for delivery!

Thanks again!

No not from a shop, it was a free bee from a fixings company.
Its states that this product has a low modulus of elasticity, and high movement capability. Nevertheless if you can get access to the base of tray and provide additional support, all the better. This Silicon also contained a powerful anti-fungicidal agent, to restrict the growth of mould. Good luck.

 

[GoneGuy]

Is there access to under the shower tray where you can check make sure none of the feet are broken or loose then maybe you could prop it up more to stop movement.
Then look into Silicon all the joints

 

[macten]

Hopefully the flex is NOT from the floor moving due to it not being braced adequately (usually is in my experience) the seal will only last a few weeks and it will go again.

 

[paul3944]

Had a job like this a couple of months ago.

I Ripped the tray out for closer investigation to find the tray was supported by ply which was completly rotted due to water ingress. This is was what caused the tray to flex.